86*(2/2*,&$/6859(<

:DWHU5HVRXUFHV,QYHVWLJDWLRQV5HSRUW¥

$VVHVVPHQWRI:DWHU4XDOLW\&RQGLWLRQVLQWKH

-%&RQYHUVH/DNH:DWHUVKHG0RELOH&RXQW\

$ODEDPD¥

3UHSDUHGLQFRRSHUDWLRQZLWKWKH

02%,/($5($:$7(5$1'6(:(56<67(0

%\&$-RXUQH\DQG$&*LOO

0RQWJRPHU\$ODEDPD


86'(3$570(172)7+(,17(5,25

*$/($1257216HFUHWDU\

86*(2/2*,&$/6859(<

&+$5/(6**52$7'LUHFWRU

)RUDGGLWLRQDOLQIRUPDWLRQZULWHWR &RSLHVRIWKLVUHSRUWFDQEHSXUFKDVHGIURP

'LVWULFW&KLHI 86*HRORJLFDO6XUYH\

86*HRORJLFDO6XUYH\ %UDQFKRI,QIRUPDWLRQ6HUYLFHV

)DLUODQH'ULYH6XLWH %R[)HGHUDO&HQWHU

0RQWJRPHU\$/ 'HQYHU&2

(PDLOGFBDO#XVJVJRY $6.86*6

,QIRUPDWLRQDERXW86*HRORJLFDO6XUYH\SURJUDPVLQ$ODEDPDLVDYDLODEOHRQWKH,QWHUQHWDW

KWWSDOZDWHUXVJVJRY

7KHXVHRIILUPWUDGHDQGEUDQGQDPHVLQWKLVUHSRUWLVIRULGHQWLILFDWLRQSXUSRVHVRQO\DQG

GRHVQRWFRQVWLWXWHHQGRUVHPHQWE\WKH86*HRORJLFDO6XUYH\
&RQWHQWV ,,,

&217(176

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

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

Purpose and scope ....................................................................................................................................................... 4

Previous investigations................................................................................................................................................ 4

Watershed characterization ................................................................................................................................................... 6

Natural factors............................................................................................................................................................. 6

Climate .............................................................................................................................................................. 6

Physiography..................................................................................................................................................... 8

Major hydrogeologic units ................................................................................................................................ 8

Major soil types................................................................................................................................................. 11

Hydrology ......................................................................................................................................................... 11

Cultural factors............................................................................................................................................................ 15

Basic water chemistry ........................................................................................................................................................... 20

Water-quality analysis methods and approach ............................................................................................................ 20

Results of water-quality analysis................................................................................................................................. 21

Major ions ......................................................................................................................................................... 21

pH and alkalinity ............................................................................................................................................... 24

Trace elements................................................................................................................................................... 27

Nutrient loading and trophic response .................................................................................................................................. 27

Nutrient analysis methods and approach..................................................................................................................... 31

Results of nutrient analysis ......................................................................................................................................... 32

Nutrient loads .................................................................................................................................................... 32

Eight-year trend analysis................................................................................................................................... 40

Spatial and temporal distribution ...................................................................................................................... 41

Comparison of nutrient loads with trophic state of lake ................................................................................... 44

Microbiological assessment .................................................................................................................................................. 46

Microbiological analysis methods and approach ........................................................................................................ 47

Results of microbiological analysis ............................................................................................................................ 47

Organic carbon characterization............................................................................................................................................ 58

Organic carbon analysis methods and approach ......................................................................................................... 59

Results of organic carbon analysis.............................................................................................................................. 60

Estimation of reactivity of the organic carbon .................................................................................................. 62

Spatial and temporal distribution ...................................................................................................................... 64

Sources of reactive organic carbon.................................................................................................................... 70

Summary and conclusions..................................................................................................................................................... 75

Selected references................................................................................................................................................................ 77

Appendix 1. Summary of descriptive statistics for selected surface-water sites in the J.B. Converse Lake 

watershed, Mobile County, Alabama, October 1990–June 1998 .................................................................... 82

Appendix 2. Monthly mean load tables for selected surface-water sites in the J.B. Converse Lake 

watershed, Mobile County, Alabama, 1990–98............................................................................................... 109

Appendix 3. Methods and results for Giardia and Cryptosporidium analyses for October 1996–May 1998 ...................... 129

),*85(6

1. Map showing locations of data-collection sites in the J.B. Converse Lake watershed 

in Mobile County, Alabama, 1990–98..................................................................................................................... 3

2. Graph showing mean monthly precipitation for 1961–90 at the Mobile Regional Airport, 

Alabama................................................................................................................................................................... 7

3. Graph showing total annual precipitation (1990–97) and departure from the mean annual 

precipitation (1961–90) of 64 inches....................................................................................................................... 7
,9 &RQWHQWV

4. Map showing digital elevation model (DEM) coverage of land-surface slope in 

subbasins of the Converse Lake watershed, Alabama .............................................................................. ............... 9

5. Map showing major geologic units in the Converse Lake watershed, Alabama...................................................... 10

6. Stratigraphy and lithology of the geologic units and water-bearing properties in the 

Converse Lake watershed, Alabama ........................................................................................................................ 11

7. Map showing major soil associations in the Converse Lake watershed, Alabama .................................................. 12

8. Graph showing streamflow duration curves for Big Creek, Crooked Creek, and 

Hamilton Creek in the Converse Lake watershed, 1990–98.................................................................................... 14

9. Map showing general land uses for the Converse Lake watershed, 1992 ................................................................ 16

10. Pie chart showing land-use percentages in the Converse Lake watershed, 1992 ..................................................... 17

11. Map showing locations of permitted point sources and plant nurseries in the 

Converse Lake watershed, 1997............................................................................................................................... 19

12. Boxplots of pH and specific conductance values at selected sites in the 

Converse Lake watershed, 1990–98......................................................................................................................... 22

13. Radial plots of median ion concentrations, in milliequivalents per liter, at Hamilton 

Creek, Crooked Creek, Boggy Branch, Converse Lake, Long Branch, 

Juniper Creek, Collins Creek, and Big Creek in the Converse Lake 

watershed, 1990–98.................................................................................................................................................. 23

14. Radial plots of ionic concentrations, in milliequivalents per liter, at Big Creek, 

Hamilton Creek, and Crooked Creek during high streamflow conditions 

and base-flow conditions in the Converse Lake watershed, 1990–98...................................................................... 25

15. Graph showing correlation between land-use category and median pH and 

acid-neutralizing capacity in tributary subbasins in the Converse Lake watershed................................................. 26

16. Boxplots of total and dissolved iron and manganese concentrations at selected sites 

in the Converse Lake watershed, 1990–98........................................................................................ ....................... 28

17. Graphs showing mean annual nutrient yields for three sites in the Converse Lake 

watershed, 1990–98............................................................................................................. ..................................... 39

18. Boxplots of total Kjeldahl nitrogen, total inorganic nitrogen, total nitrogen, and total 

phosphorus concentrations at selected sites in the Converse Lake watershed, 1990–98......................................... 42

19. Graphs showing seasonal variations in chlorophyll a, and organic and inorganic 

nitrogen concentrations in the Converse Lake watershed, 1996–98 ........................................................................ 43

20. Graph showing temporal variations in nutrient loadings to the lake during the growing 

season and the lake response to these loadings........................................................................................................ 45

21. Boxplots showing ranges of fecal coliform, fecal streptococcus, and E. coli

concentrations at selected sites in the Converse Lake watershed, 1990–98 ............................................................ 49

22. Boxplots showing seasonal fecal coliform, fecal streptococcus, and E. coli

concentrations at selected sites in the Converse Lake watershed, 1990–98 ............................................................ 50

23. Map showing ranges in geometric mean concentrations of fecal coliform and 

fecal streptococcus for 1990–98, and E. coli and fecal coliform for 1996–98 ........................................................ 53

24. Scatter plots showing relations between percentages of various land-use types and 

median fecal coliform concentrations at sites in the Converse Lake watershed...................................................... 55

25. Graph showing quarterly and mean results of monitoring for trihalomethane concentrations 

in treated water at four municipal water supplies in Alabama as part of the Information Collection 

Rule requirements .................................................................................................................................................... 61

26. Graph showing mean trihalomethane concentrations in treated water from selected municipal water 

supplies in the United States .................................................................................................................................... 62

27. Correlation coefficients and scatter plots of trihalomethane-formation potential and potential surrogate 

concentrations in the Converse Lake watershed, 1996–98 ...................................................................................... 63

28. Boxplots of total organic carbon, dissolved organic carbon, and tannin and lignin 

concentrations at selected sites in the Converse Lake watershed, 1996–98 ............................................................ 65

29. Map showing range in median concentrations of dissolved organic carbon, tannin and lignin, 

total organic carbon, and ultraviolet absorbance at 254 nanometers in the Converse Lake 

watershed, 1996–98.................................................................................................................................................. 66
&RQWHQWV 9

30. Boxplots of ultraviolet absorbance at 254 nanometers for unfiltered (TOC) and filtered 

(DOC) samples and specific absorbance at selected sites in the Converse Lake watershed, 

1996–98 ........................................................................................................................ ........................................... 67

31. Graph showing range in trihalomethane-formation potential for selected tributary and 

lake sites in the Converse Lake watershed, 1996–98 .............................................................................................. 68

32. Graph showing correlation between percent land-use categories and median concentrations 

of total organic carbon, dissolved organic carbon, tannin and lignin, and ultraviolet absorbance at 

254 nanometers in the Converse Lake watershed, 1996–98.................................................................................... 69

7$%/(6

1. Descriptions of data-collection sites and sampling characteristics in the Converse Lake 

watershed, Alabama, 1990–98 ................................................................................................................................ 5

2. Physical characteristics of Converse Lake............................................................................................................... 6

3. Streamflow conditions in selected tributaries to Converse Lake, October 1990 to 

September 1998 ....................................................................................................................................................... 13

4. Land use in selected subbasins of the Converse Lake watershed, in acres and percent 

acreage of subbasin, from 1992 Multi-Resolution Land Characteristics (MRLC) data ......................................... 18

5. Spearman rho correlation coefficients for percentage of land use and median levels of pH, 

acid-neutralizing capacity, and specific conductance in the Converse Lake watershed.......................................... 26

6. Potential changes in lake characteristics related to trophic state............................................................................. 29

7. National Eutrophication Survey guidelines for trophic state determination............................................................ 30

8. Organization for Economic Cooperation and Development indices for trophic state 

determination based on scientific opinion............................................................................................................... 30

9. Regression summary for the seven-parameter, log-linear model used to estimate nutrient 

concentrations at selected sites in the Converse Lake watershed............................................................................ 33

10. Range in nutrient yields from nonpoint sources ...................................................................................................... 36

11. Annual nutrient loads and yields for selected tributary sites in the Converse Lake 

watershed for water year 1991................................................................................................................................. 36

12. Annual and mean annual nutrient loads and yields for Big Creek (site BIG), Converse Lake 

watershed, water years 1991–98.............................................................................................................................. 37

13. Annual and mean annual nutrient loads and yields for Crooked Creek (site CRO), 

Converse Lake watershed, water years 1991–98..................................................................................................... 37

14. Annual and mean annual nutrient loads and yields for Hamilton Creek (site HAM), 

Converse Lake watershed, water years 1991–98..................................................................................................... 38

15. Estimated mean annual nutrient contributions to Converse Lake............................................................................ 38

16. Results of the seasonal Kendall tau test for trends in unadjusted and flow-adjusted nutrient 

concentrations at selected sites in the Converse Lake watershed, 1990–98............................................................ 40

17. Seasonal and annual change in trophic potential and response variables in Converse Lake, 

1992–97 ................................................................................................................................................................... 44

18. Standards and criteria for concentrations of fecal bacteria set by the Alabama Department 

of Environmental Management and the U.S. Environmental Protection Agency for various 

water-use classifications .......................................................................................................................................... 48

19. Seasonal median bacterial concentrations for selected sites in the Converse Lake Watershed, 

1990–98 ................................................................................................................................................................... 51

20. Geometric means of bacterial concentrations at sites in the Converse Lake watershed 

for the period October 1990–June 1998 .................................................................................................................. 52

21. Results of the seasonal Kendall tau test for trends in unadjusted and flow-adjusted bacterial 

concentrations at selected sites in the Converse Lake watershed, 1990–98............................................................ 54

22. General geochemical characteristics of naturally occurring organic carbon compounds in 

surface water derived from lignin-derived (allochthonous) or microbial/algal-derived 

(autochthonous) sources ......................................................................................................................................... 59

23. Types and potential sources of organic carbon in surface-water samples collected in the 

Converse Lake watershed ........................................................................................................................................ 60
9, &RQWHQWV

24. Spearman rho correlation coefficients for land-use categories and median levels of total 

organic carbon, dissolved organic carbon, tannin and lignin, and ultraviolet absorbance at 

254 nanometers in the Converse Lake watershed .................................................................................. .................. 69

25. Spearman rho correlation matrix for selected constituents in seven tributary sites and one lake site 

in the Converse Lake watershed............................................................................................................................... 71

&219(56,21)$&72569(57,&$/'$7807(03(5$785($1'$&521<06$1'

$%%5(9,$7,216

Sea level: In this report, “sea level” refers to the National Geodetic Vertical Datum of 1929 (NGVD

of 1929)—a geodetic datum derived from a general adjustment of the first-order level nets of the

United States and Canada, formerly called Sea Level Datum of 1929.

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

Celsius (°C) as follows:

°C = 5/9 (°F - 32)

Acronyms and abbreviations:

ADEM Alabama Department of Environmental Management

ANC acid-neutralizing capacity

CERCLA Comprehensive Environmental Response, Compensation, and Liability Act

DEM digital elevation model

DBP disinfection by-product

DOC dissolved organic carbon

GIS geographic information system

HAA haloacetic acid

ICR Information Collection Rule

LOWESS Locally Weighted Regression and Smoothing of Scatter Plots

MAWSS Mobile Area Water and Sewer System

MBAS methylene blue activated substances

MCL maximum contaminant level

MRLC Multi-Resolution Land Characteristic

MVUE Minimum Variance Unbiased Estimator

NRCS Natural Resource Conservation Service

NWIS National Water Information System (U.S. Geological Survey database)

OECD Organization for Economic Cooperation and Development

PCS permit compliance system

PVC polyvinyl chloride

STATSGO State Soil Geographic Data Base

STORET Storage and Retrieval System (U.S. Environmental Protection Agency database)

0XOWLSO\ E\ 7RREWDLQ

Length

inch (in.) 2.54 centimeter

foot (ft) 0.3048 meter

Area

square mile (mi2

) 259 hectare

square mile (mi2

) 2.590 square kilometer

Flow

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

foot per mile (ft/mi) 0.1894 meter per kilometer
&RQWHQWV 9,,

Acronyms and abbreviations (continued):

SUVA specific ultraviolet absorbance

THM trihalomethane

THM-FP trihalomethane-formation potential

TIN total inorganic nitrogen

TKN total Kjeldahl nitrogen

TOC total organic carbon

TRI Toxic Release Inventory

TSI trophic state index

USEPA U.S. Environmental Protection Agency

USGS U.S. Geological Survey

UVA ultraviolet absorbance

UV-Vis Ultraviolet -Visible Spectrum

acre-foot acre-ft

B boron

Br bromine

C carbon

Ca calcium

CaCO3 calcium carbonate

Cl chlorine

cm centimeter

col/100 mL colonies per 100 milliliters

CO3 carbonate

F fluorine

Fe iron

ft3/s cubic feet per second

g/d gram per day

g/yr gram per year

HCO3 bicarbonate

Hg mercury

K potassium

kg kilogram

kg/d kilogram per day

(kg/ha)/yr kilogram per hectare per year

kg/yr kilogram per year

m meter

m2 square meter

Mg magnesium

mg/L milligram per liter

(mg/L)/yr milligram per liter per year

mL milliliter

mm millimeter

Mn manganese

m/yr meter per year

N nitrogen

Na sodium

nm nanometer

P phosphorus

ppm parts per million

SiO2 silica

SO4 sulfate

μg/L microgram per liter

μS/cm microsiemens per centimeter

UVA-DOC ultraviolet absorbance of dissolved organic carbon at 254 nanometers

UVA-TOC ultraviolet absorbance of total organic carbon at 254 nanometers

Water year is the period October 1 through September 30 and is identified by the year in which it ends.
$EVWUDFW 

$VVHVVPHQWRI:DWHU4XDOLW\&RQGLWLRQVLQWKH

-%&RQYHUVH/DNH:DWHUVKHG0RELOH&RXQW\

$ODEDPD¥

%\&$-RXUQH\DQG$&*LOO

$%675$&7

J.B. Converse (Converse) Lake is a 3,600-

acre, tributary-storage reservoir in Mobile County, 

southwestern Alabama. The lake serves as the 

primary drinking-water supply for the city of 

Mobile. The Converse Lake watershed lies within 

the Coastal Plain Physiographic Province. 

Semiconsolidated to unconsolidated sediments of 

sand, silt, gravel, and clay underlie the watershed, 

and are covered by acidic soils. Land use in the 

watershed is mainly forest (64 percent) and 

agriculture (31 percent). Residential and 

commercial development account for only 

1 percent of the total land use in the watershed.

Converse Lake receives inflow from seven 

major tributaries. The greatest inflows are from 

Big Creek, Crooked Creek, and Hamilton Creek 

that had mean annual streamflows of 72.2, 19.4, 

and 25.0 cubic feet per second, respectively, for 

the period 1990 to 1998, which represents about 

72 percent of the total annual streamflow to the 

lake. The total mean annual inflow to the lake is 

estimated to be about 163 cubic feet per second.

In general, water quality in Converse Lake 

and its tributaries meets the criteria established by 

the Alabama Department of Environmental 

Management (ADEM) for drinking-water 

supplies, whole-body contact, and aquatic life. 

The exceptions include acidic pH levels, iron and 

manganese levels above secondary or aesthetic 

criteria, and fecal bacterial levels in some 

tributaries above whole-body contact 

(swimmable) criteria. The pH levels throughout 

the watershed were commonly below the criteria 

level of 6.0, but this appears to have been a 

naturally occurring phenomenon caused by poorly 

buffered soil types, resistant sediments, and 

forested land use. Median iron and manganese 

levels were above aesthetic criteria levels of 

300 and 50 micrograms per liter, respectively, in 

some tributaries. All tributary sites in the Converse 

Lake watershed had median and minimum 

dissolved-oxygen concentrations above the 

ADEM criteria level of 5 milligrams per liter 

except for Boggy Branch, which had a minimum 

dissolved-oxygen concentration of 3.7 milligrams 

per liter.

The degree to which nutrient contributions 

from tributaries were causing nutrient enrichment 

and eutrophication in Converse Lake was 

assessed. Trend analysis detected little or no 

change in nutrient concentrations at the tributary 

and lake sites in the Converse Lake watershed 

from the 1991 to 1998 water years. Nutrient 

concentrations at most tributary sites exhibited a 

significant, positive relation with streamflow that 

indicated the dominant source of nutrient input to 

the watershed is from nonpoint contributions. 

From 1990 to 1998, computed mean annual loads 

of 75,400 kilograms of total nitrogen, 

36,950 kilograms of total Kjeldahl nitrogen, 

28,870 kilograms of total inorganic nitrogen, and 

3,480 kilograms of total phosphorus were 

contributed to the lake by Big Creek, Hamilton 

Creek, and Crooked Creek combined. These mean 
 $VVHVVPHQWRI:DWHU4XDOLW\&RQGLWLRQVLQWKH-%&RQYHUVH/DNH:DWHUVKHG0RELOH&RXQW\$ODEDPD¥

annual loads of nutrients corresponded to 

borderline eutrophic/mesotrophic conditions in 

the lake. Of the combined loads, 62 percent of the 

total nitrogen, 70 percent of the total Kjeldahl 

nitrogen, 54 percent of the total inorganic 

nitrogen, and 47 percent of the total phosphorus 

originated from the forested subbasin of Big 

Creek. The more residential and agricultural 

subbasins of Crooked Creek and Hamilton Creek, 

however, yielded over twice the total phosphorus 

load per hectare of land use. Crooked and 

Hamilton Creek subbasins also had higher yields 

of the more bioavailable total inorganic nitrogen. 

A simplistic empirical model could not explain the 

relation between year-to-year nutrient contributions to Converse Lake from the tributaries and the 

lake’s ability to assimilate those contributions.

The potential presence of pathogens in the 

lake and its tributaries was assessed based on fecal 

bacterial concentrations. Fecal bacterial 

concentrations at some tributary sites were above 

existing criteria for swimmable uses. 

Contributions of fecal bacteria from tributaries to 

the lake, however, did not appear to affect the lake 

because fecal bacterial concentrations at lake sites 

were one to two orders of magnitude lower than 

tributary sites and well below criteria levels. 

Juniper Creek had the highest fecal bacterial 

concentrations during the study. Trend analysis 

showed that flow-adjusted fecal streptococcus 

concentrations increased at Juniper Creek during 

the 8 years of data collection. Giardia cysts and 

Cryptosporidium oocysts were detected 

infrequently at sites in the lake and the raw-water 

intake during the monitoring effort. Most of the 

detections occurred during the summer months, 

but no clear relation between season and cyst 

density or cyst concentrations in the water supply 

can be established because of the infrequent 

detections.

Naturally occurring organic carbon 

compounds derived from the decay of plant 

material on land were the major source of organic 

carbon in the Converse Lake watershed. Reactive 

organic carbon had a greater potential to form 

trihalomethanes as a result of chlorination during 

water treatment. In the lake, algae was considered 

an important source of organic carbon as indicated 

by strong, positive, statistically significant 

correlations among chlorophyll a, total organic 

carbon, and dissolved organic carbon. The algalderived organic carbon, however, was not 

considered the major source of the reactive organic 

carbon as indicated by the absence of significant 

statistical correlations between chlorophyll a, total 

organic carbon, dissolved organic carbon, 

ultraviolet absorbance at 254 nanometers, and 

trihalomethane-formation potential.

,1752'8&7,21

J.B. Converse Lake, formerly known as Big 

Creek Lake and hereafter referred to as Converse Lake, 

is a 3,600-acre tributary-storage reservoir in Mobile 

County in southwestern Alabama (fig. 1). The lake is 

the primary source of drinking water for the Mobile 

area and a popular recreational spot for fishing and 

boating activities, although swimming and water skiing 

are prohibited. The warm Gulf Coast climate attracts 

recreational fishermen year round to the lake, and 

supports a growing plant nursery industry in the 

watershed. At present (2001), the watershed is mostly 

forested and rural, although residential development 

has increased throughout the area during the past 

10 years. 

Rapid, unmanaged, and(or) pervasive changes in 

human activities in a watershed can have profound, 

long-term effects on the water quality of a lake or 

reservoir. Because Converse Lake serves as a source of 

drinking water, it is important to understand the effects 

that land use and future development may have on 

water quality. To effectively manage and protect the 

water resources of the lake, the following three 

questions must be answered.

1. Does the water quality of the lake and its 

tributaries meet the intended uses of the water?

2. Is the water quality of the lake and its tributaries 

changing over time?

3. What real or potential sources of water-quality 

problems exist in the watershed? 

This report addresses these questions and also serves as 

a source-water assessment, which is a required part of 

the new protection strategy for public water supplies in 

Alabama.
,QWURGXFWLRQ 

)LJXUH /RFDWLRQVRIGDWDFROOHFWLRQVLWHVLQWKH-%&RQYHUVH/DNHZDWHUVKHGLQ0RELOH&RXQW\$ODEDPD

¥
 $VVHVVPHQWRI:DWHU4XDOLW\&RQGLWLRQVLQWKH-%&RQYHUVH/DNH:DWHUVKHG0RELOH&RXQW\$ODEDPD¥

The Mobile Area Water and Sewer System 

(MAWSS) manages Converse Lake and the E. Morgan 

Stickney and Harry E. Myers Water Filtration 

Facilities. These two facilities treat the raw water 

withdrawn by a pumping station on Converse Lake 

(site LHAM; fig. 1), and then deliver treated water to 

the city of Mobile. Much of the land surrounding the 

lake is covered by a combination of evergreen and 

deciduous forest and is owned by the MAWSS. The 

remaining part of the watershed consists of a 

combination of forest, pastures and dairy farms, plant 

nurseries, pecan groves, and residential areas that 

include septic-tank systems for sewage disposal. These 

land uses contribute nonpoint sources of pollutants that 

influence the water quality in Converse Lake and its 

tributaries. Runoff from rainfall in the watershed 

washes contaminants from the land surface into the 

tributaries, which in turn deliver contaminants to the 

lake. Sediment, fecal indicator bacteria, organic carbon 

compounds, and nutrients commonly are present in 

runoff from agricultural and rural residential areas, and 

can impair the quality of water. Effluent from septictank systems also can contribute similar contaminants 

during periods of little or no runoff if the density of the 

tanks exceeds the capacity of the soil to assimilate the 

sewage.

Elevated nutrient concentrations in lake water 

can produce excessive algal growth and increase the 

total organic carbon present in the water. The presence 

of fecal indicator bacteria in the lake water requires 

treatment of drinking water with chlorine-related 

disinfectants. During this disinfection process, 

however, the chlorine can react with naturally 

occurring or culturally derived organic carbon 

compounds to produce by-products that are suspected 

carcinogens. Any process that increases the level of 

total organic carbon present in the raw water, increases 

the chances for these by-products to form during the 

disinfection processes.

3XUSRVHDQG6FRSH

 The purpose of this report is to describe the 

assessment of water quality in the Converse Lake 

watershed during 1990–98 and the influence of landuse practices on water quality in the watershed. The 

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

the MAWSS, began monitoring streamflow and water 

quality in the Converse Lake watershed in October 

1990. The focus of this monitoring program is on the 

temporal and spatial distribution of concentrations of 

nutrients, fecal bacteria, and organic carbon in the lake 

and its tributaries. The water-quality data and analytical 

results presented in this report will be useful in 

managing and protecting the drinking-water supply for 

the city of Mobile. Providing information to better 

define and manage the quality of water resources is 

among the highest priority issues of the Cooperative 

Water Program of the USGS. This investigation also 

provides information to improve watershed 

characterization of local sources of water supply, 

determine the effects of land-use practices on surfacewater quality, and identify waterborne microbiological 

threats to human health, all of which are priority issues 

of the Cooperative Water Program.

A data-collection network was established at 

seven tributary sites and two lake sites in the Converse 

Lake watershed (fig. 1; table 1). Concentrations of 

nutrients and fecal bacterial indicator levels have been 

monitored at these sites at varying frequencies 

(monthly to quarterly) since October 1990, and 

concentrations of organic carbon have been monitored 

monthly since October 1996. Three gaging stations 

located on major tributaries to Converse Lake (fig. 1) 

collect continuous streamflow record. 

This report consists of four sections that discuss 

spatial and temporal variations in basic water 

chemistry, nutrients, fecal indicators, and organic 

carbon and their relation to land-use practices in the 

watershed. Additionally, the nutrient section includes 

the estimated annual nutrient load data from three 

gaged tributary sites in the watershed, an 8-year trend 

analysis of the nutrient concentrations in the lake and 

its tributaries, and a comparison of annual nutrient 

loads to the trophic state of the lake. The 

microbiological assessment section describes the 

8-year trend analysis of fecal coliform and fecal 

streptococcus concentrations in the lake and its 

tributaries and compares the levels of fecal indicator 

bacteria to the Alabama Department of Environmental 

Management (ADEM) water-quality standards and 

criteria. The organic carbon section characterizes the 

reactive nature of organic carbon and its probable 

source (algal, terrestrial). 

3UHYLRXV,QYHVWLJDWLRQV

States are required by section 314(a) of the Clean 

Water Act to conduct assessments of the water quality 

of publicly owned lakes (U.S. Environmental 
3UHYLRXV,QYHVWLJDWLRQV 

Protection Agency, 1981, 1989). In compliance with 

the Clean Water Act requirements, the ADEM initiated 

the Reservoir Water Quality Monitoring Program in 

1990 to address trophic-state trends in lakes. The 

results of ADEM’s monitoring program were published 

for 1985 to 1995 (Alabama Department of Environmental Management, 1996) and for 1997 (Alabama 

Department of Environmental Management, 1999).

Development of anoxic, or oxygen-depleted, 

conditions during stratification is a common 

occurrence in mesotrophic and eutrophic lakes. 

Vertical profiles of dissolved-oxygen concentrations, 

specific conductance, and water temperature at several 

cross sections in Converse Lake have helped to identify 

the seasonal occurrence of anoxic conditions (Journey 

and others, 1995; Bayne and others, 1998). 

In 1995, the USGS published a report that 

describes streamflow and nutrient contributions of 

major tributaries to Converse Lake (Journey and others, 

1995). Nutrient loads to the lake were computed for 

1991 and 1992. Big Creek and Hamilton Creek were 

estimated to have the highest nitrogen loads. Crooked 

and Juniper Creeks also had relatively high nitrogen 

loads compared to Collins Creek, an adjacent tributary 

basin with similar drainage area and land use. Big 

Creek, Crooked Creek, and Hamilton Creek subbasins 

contributed the highest phosphorus loads, and these 

subbasins also had a variety of land-use practices, such 

as pastures, plant nurseries, and residential areas. 

In its two water-treatment plants, the MAWSS 

monitors raw and finished water for microbial 

contaminants and disinfection by-products in 

compliance with the 1996 amendments to the Safe 

Drinking Water Act: Information Collection Rule and 

the Enhanced Surface Water Treatment Rule (U.S. 

Environmental Protection Agency, 1996a,b,c). In 1995, 

concentrations of total organic carbon (TOC) 

periodically increased in raw and finished water at both 

treatment facilities. The treatment of the increased 

TOC concentrations resulted in higher concentrations 

of disinfection by-products in the finished water. In 

1995, the sources of the periodic increases in TOC 

were not understood. 

7DEOH 'HVFULSWLRQVRIGDWDFROOHFWLRQVLWHVDQGVDPSOLQJFKDUDFWHULVWLFVLQWKH&RQYHUVH/DNHZDWHUVKHG$ODEDPD¥

[USGS, U.S. Geological Survey; mi2, square mile; Q, quarterly; M, monthly; —, not applicable]

6LWH

ODEHO

ILJ

86*6

VWDWLRQ

QXPEHU

6WDWLRQQDPH

'UDLQDJH

DUHD

PL



6DPSOLQJIUHTXHQF\

6WUHDPIORZ 0DMRU

LRQV 1XWULHQWV )HFDOEDFWHULD

2UJDQLF

FDUERQ

BIG 02479945 Big Creek at County Road 63 near 

Wilmer

31.5 Continuous 

record

Q Ma

Qb

a

Monthly samples were collected for the period October 1990 to September 1992.

b

Quarterly samples were collected for the period October 1992 to June 1998.

Mc

Qd

c

Monthly samples were collected for the periods October 1990 to September 1992 and October 1996 to June 1998.

d

Quarterly samples were collected for the period October 1992 to September 1996.

Me

e

Monthly samples were collected for the period October 1996 to June 1998.

JUN 02479948 Juniper Creek at Glenwood Road 

near Fairview

9.22 Partial record Q Ma

Qb

Mc

Qd

Me

COL 02479950 Collins Creek at Glenwood Road 

near Fairview

8.54 Partial record Q Ma

Qb

Mc

Qd

Me

LON 02479955 Long Branch near Wilmer 2.85 Partial record Q Ma

Qb

Mc

Qd

Me

BOG 02479960 Boggy Branch near Wilmer 3.17 Partial record Q Ma

Qb

Mc

Qd

Me

CRO 02479980 Crooked Creek near Fairview 8.08 Continuous 

record

Q Ma

Qb

Mc

Qd

Me

LCRO 02479985 Crooked Creek at mouth (Lake) 

near Wilmer

— —Qf

f

All samples were collected in October 1996.

Qf Mf Me

HAM 02480002 Hamilton Creek at Snow Road near 

Semmes

8.22 Continuous 

record

Q Ma

Qb

Mc

Qd

Me

LHAM 02480004 Hamilton Creek (Lake at the intake) 

near Semmes

— — QMa

Qb

Mc

Qd

Me
 $VVHVVPHQWRI:DWHU4XDOLW\&RQGLWLRQVLQWKH-%&RQYHUVH/DNH:DWHUVKHG0RELOH&RXQW\$ODEDPD¥

7DEOH 3K\VLFDOFKDUDFWHULVWLFVRI&RQYHUVH/DNH

&KDUDFWHULVWLF 9DOXH

Total volume 52,000 acre-feet

Surface area 3,600 acres

Mean depth 14.4 feet

Maximum depth 50 + feet

Mean annual inflow 163 cubic feet per second

Hydraulic residence time 0.44 year

160 days

Drainage area of watershed 103 square miles

:$7(56+('&+$5$&7(5,=$7,21

Converse Lake was formed from the 

impoundment of Big Creek in 1952 and was previously 

known as Big Creek Lake. The drainage area of the 

watershed is 103 mi2

 at the dam (table 2). The lake 

volume is 52,000 acre-ft, or approximately 17 billion 

gallons of water at the normal operational pool level of 

110 ft above mean sea level (City of Mobile, Board of 

Water and Sewer Commissioners, written commun., 

October 5, 1994). Converse Lake has a mean depth of 

14.4 ft at full pool, with maximum depths of over 50 ft 

near the dam and spillway (table 2). The pump station 

is located in a small embayment below the mouth of 

Hamilton Creek (site LHAM, fig. 1). The embayment 

has a maximum depth of 27 ft. 

major geologic units (1:250,000 scale); major soil types 

(State Soil Geographic [STATSGO] database, 

1:250,000 scale); Landsat satellite imagery of major 

land use and land cover (1992 Multi-Resolution Land 

Characteristics [MRLC], 30-meter resolution); and 

locations of point sources in the watershed (U.S. 

Environmental Protection Agency [USEPA] Toxic 

Release Inventory [TRI], hazardous-waste permit 

compliance system [PCS], and Superfund 

[Comprehensive Environmental Response, 

Compensation, and Liability Act—CERCLA] sites). 

Spatial differences in water quality were compared to 

the spatial coverage of environmental factors to identify 

potential relations. This integrated approach helped 

identify key factors that influence water quality, and 

evaluate the present conditions in the lake and its 

tributaries. 

1DWXUDO)DFWRUV

The interaction of many environmental factors 

affects the quality of the water in a watershed. Some 

natural factors in a watershed, such as climate, 

topography, rock and soil types, and vegetation, can 

influence water quality differently. 

&OLPDWH

The study area is close to the Gulf Coast and, 

thus, the climate is subtropical. Precipitation occurs 

almost exclusively as rainfall. Snowfall accumulation is 

rare. Several types of weather patterns influence the 

climate. The Gulf of Mexico produces warm, humid air 

masses that move inland and provide precipitation in 

the form of sporadic thunderstorms, especially during 

the summer. Extremely high-intensity rainfall is 

produced from tropical systems that enter the Gulf of 

Mexico (tropical depressions, storms, and hurricanes) 

and move inland in late summer and early fall (July to 

September). In winter, the climate is further influenced 

by arctic fronts that move south from the Midwest. 

Frontal storms contribute more continuous precipitation 

and cooler temperatures. 

The mean annual precipitation in the Mobile area 

for the 30-year period 1961–90 was 64 in. and ranged 

from 44 to 86 in. (National Oceanic and Atmospheric 

Administration, 1998). Mean monthly precipitation 

ranged from 3 in. in October to 7 in. in August (fig. 2). 

A distinct dry period occurred during late fall (October 

to November). Two wet periods were identified during 

The Converse Lake watershed is located in 

Mobile County west of the city of Mobile near the 

Alabama-Mississippi State line. The lake is designated 

by the ADEM for aquatic life and public water-supply 

use (Alabama Department of Environmental 

Management, 1994b). Management of the lake requires 

an understanding of all factors influencing the water 

quality. A sound science-based management plan for 

development and growth in the watershed considers all 

aspects of naturally occurring and culturally induced 

factors in order to aid in the protection of the water 

quality of the lake and its tributaries. 

 For this investigation, spatial coverages of 

natural and cultural features in the watershed were 

obtained from geographic information system (GIS) 

databases. ArcInfo and ArcView 3.2 GIS coverages 

were developed and used to integrate the information on 

environmental factors and water quality. The coverages 

include basin and major tributary subbasin drainage 

areas (1:24,000 scale); streams, roads, railroads, and 
:DWHUVKHG&KDUDFWHUL]DWLRQ 

early spring (March) and late summer (July to 

August). The late summer wet period was related to 

tropical storms moving inland from the Gulf of 

Mexico.

During the study period, the driest years were 

1990 and 1994 when annual precipitation was about 

8 in. below the normal mean annual precipitation of 

64 in. (fig. 3). The wettest years were 1991 and 1995 

when annual precipitation was more than 15 in. above 

the normal mean annual precipitation. 

The mean annual temperature during the study 

period was 67.5 °F. Temperatures in the study area 

generally are above freezing throughout most of the 

year, and mean monthly temperatures range from 50 °F 

in January to 82 °F in July (National Oceanic and 

Atmospheric Administration, 1998). 

)LJXUH 0HDQPRQWKO\SUHFLSLWDWLRQIRU¥DWWKH0RELOH5HJLRQDO$LUSRUW$ODEDPD

)LJXUH 7RWDODQQXDOSUHFLSLWDWLRQ¥DQGGHSDUWXUHIURPWKHPHDQDQQXDO

SUHFLSLWDWLRQ¥RILQFKHV
 $VVHVVPHQWRI:DWHU4XDOLW\&RQGLWLRQVLQWKH-%&RQYHUVH/DNH:DWHUVKHG0RELOH&RXQW\$ODEDPD¥

3K\VLRJUDSK\

The Converse Lake watershed lies within the 

Southern Pine Hills District of the East Gulf Coastal 

Plain section of the Coastal Plain Physiographic 

Province (Sapp and Emplaincourt, 1975; fig. 1). Land 

surface in the Southern Pine Hills District slopes gently 

in a southwesterly direction toward the coast.

In the Converse Lake watershed, the maximum 

altitude of the land surface decreases from about 290 ft 

above mean sea level in the northern part of the 

watershed to 250 ft in the southern part. The lowest 

point in the watershed is the lake surface, which has an 

altitude ranging between 105 and 115 ft above mean 

sea level. A spatial coverage of land-surface slope for 

the watershed was obtained from digital elevation 

models (DEMs). The majority of the watershed has a 

gentle slope of less than 1 degree. Maximum slopes of 

4 degrees are found at altitudes ranging between 

150 and 200 ft (fig. 4); steeper slopes may result from 

changes in lithology. Because of the steeper slopes, 

which allow for greater erosion and quicker transport 

of contaminants, this area has a greater potential for 

contributing contaminants to the lake and its tributaries 

during runoff conditions.

0DMRU+\GURJHRORJLF8QLWV

Two geologic units consisting of semiconsolidated to unconsolidated sand, silt, gravel, and 

clay of Tertiary age underlie the Converse Lake 

watershed (fig. 5). The two units are undifferentiated 

sedimentary deposits of Miocene age (named Miocene 

Series undifferentiated) and the Citronelle Formation 

of Pliocene age. These units dip to the southwest at 

about 5 ft/mi near the outcrop area of the Citronelle 

Formation in northern Mobile County to as much as 

50 ft/mi near the coast (Reed, 1971). The units also 

thicken to the southwest.

The Miocene Series undifferentiated, which is 

the older of the two units, is marine and estuarine in 

origin and consists of laminated to thinly bedded, 

laterally extensive clays, sands, and sandy clays (fig. 6; 

Reed, 1971). The texture ranges from fine to coarse 

sands that are locally cross bedded (Mooty, 1988). 

Some outcrops of this unit have beds of sand that 

contain gravel and petrified plant fossils, and clays that 

contain carbonized leaf remains. The Miocene Series 

undifferentiated is about 3,000 ft thick near the coast 

(Davis, 1987). 

The Citronelle Formation overlies the Miocene 

Series undifferentiated. The Citronelle Formation is 

relatively thin (about 30 ft) in the northern part of the 

watershed, but thickens toward the south to about 

130 ft near the coast (fig. 6; Davis, 1987). Sediments of 

this unit consist of gravelly sands and sandy clays. Thin 

(5 to 15 ft thick) lenses of sandy clay and clayey sand 

are interbedded with gravelly sand in some areas of the 

unit. The base of the Citronelle Formation has a high 

clay and iron content and includes limonite-cemented 

(iron hydroxide) gravelly sand. The Citronelle 

Formation grades into discontinuous, sandy-clay and 

clayey-sand lenses interbedded with gravelly sand. 

The major aquifer system contributing ground 

water to the streams and lakes in the Converse Lake 

watershed is the Pliocene-Miocene aquifer, which 

consists of the Citronelle Formation (of Pliocene age) 

and the Miocene Series undifferentiated (Mooty, 

1988). Although clayey sediments in the Miocene 

Series cause the aquifer to behave as if it were 

semiconfined at depth, the sand and gravel beds of the 

Citronelle Formation and upper part of the Miocene 

Series are hydraulically connected to the land surface. 

As a result, ground water is susceptible to 

contamination from the watershed surface. Areas in the 

watershed most susceptible to contamination from the 

surface are those that are relatively flat with very 

permeable soils. 

These types of clastic sediments tend to be 

relatively resistant to weathering and contribute 

relatively little to runoff or surface-water chemistry 

(Drever, 1988). Waters draining resistant sediments 

tend to be relatively dilute in total dissolved solids, 

commonly less than 100 mg/L. The dilute waters tend 

to have relatively low concentrations of base cations 

and bicarbonate, which help to neutralize acid. As a 

result, the pH of waters draining clastic sediments tend 

to be more acidic than waters draining other rock types. 

Also, the iron-rich cement in the sediment can elevate 

concentrations of iron in the ground water, which in 

turn discharges to streams and lakes.
1DWXUDO)DFWRUV 

)LJXUH 'LJLWDOHOHYDWLRQPRGHO'(0FRYHUDJHRIODQGVXUIDFHVORSHLQVXEEDVLQVRIWKH

&RQYHUVH/DNHZDWHUVKHG$ODEDPD
 $VVHVVPHQWRI:DWHU4XDOLW\&RQGLWLRQVLQWKH-%&RQYHUVH/DNH:DWHUVKHG0RELOH&RXQW\$ODEDPD¥

)LJXUH 0DMRUJHRORJLFXQLWVLQWKH&RQYHUVH/DNHZDWHUVKHG$ODEDPD
1DWXUDO)DFWRUV 

0DMRU6RLO7\SHV

The type of soil in a particular region is 

influenced by climate, the nature of the bedrock, 

landscape relief, vegetation, and the time over which 

the soil-forming process occurs. These factors interact 

to produce characteristic soil profiles that vary with 

depth and complexity. The major soil type in the 

Converse Lake watershed is classified as ultisol (Hajek 

and others, 1975). These deeply weathered soils are 

common in the Southeast because of the humid 

climate. 

The State Soil Geographic (STATSGO) database 

for Alabama contains digital geographic data created 

by generalizing more detailed soil survey maps onto 

USGS 1:250,000-scale topographic quadrangle series 

maps (U.S. Department of Agriculture, 1994). This 

database provides soil types in a particular area on a 

regional scale. Four major soil associations are present 

in the Converse Lake watershed (fig. 7)—TroupSmithton-Bibb (AL 213), Troup-Heidel-Bama 

(AL 221), Notcher-Saucier-Malbis (AL 223), and 

Esto-Troup-Benndale (AL 226). The Troup-HeidelBama soil series covers 77.8 percent of the watershed. 

The Troup-Smithton-Bibb soil series covers 

21.3 percent of the watershed, all of which is in the Big 

Creek subbasin. The major soil associations of 

Notcher-Saucier-Malbis and Esto-Troup-Benndale 

account for less than 1 percent of the watershed’s soil 

cover. 

Each soil series has certain properties or 

characteristics associated with it. All of the major soils 

are deep and highly acidic (Hajek and others, 1975). 

Troup, Benndale, and Bama soil series are classified as 

well drained with moderate permeability. Smithton soil 

series is poorly drained with moderately slow 

permeability, and potentially has a perched water table. 

Malbis soil series is moderately well drained and tends 

to have a perched water table. 

+\GURORJ\

Understanding the hydrologic cycling of water in 

the Converse Lake watershed is necessary to identify 

the potential and actual sources of contaminants to the 

lake and its tributaries. Ground water in the surficial 

aquifer system discharges to the lake and its tributaries. 

Contaminants can infiltrate from the land surface into 

the ground water in the surficial aquifer. Ground water 

then can be a source of contamination to the lake and 

tributaries. The tributaries supply varying amounts of 

annual inflow to the lake, carrying loads of nutrients, 

bacteria, and organic carbon. The ability of the lake to 

assimilate the contaminant loads is, in part, related to 

the amount of inflow to and outflow from the lake. The 

)LJXUH 6WUDWLJUDSK\DQGOLWKRORJ\RIWKHJHRORJLFXQLWVDQGZDWHUEHDULQJSURSHUWLHVLQWKH&RQYHUVH/DNHZDWHUVKHG$ODEDPD

6\VWHP 6HULHV *HRORJLFXQLW 7KLFNQHVV

IHHW /LWKRORJ\ $TXLIHU <LHOG 4XDOLW\RI

JURXQGZDWHU

7HUWLDU\

3OLRFHQH &LWURQHOOH

)RUPDWLRQ

¥ 6DQGEURZQUHG

DQGRUDQJHILQHWR

FRDUVHJUDLQHG

JUDYHOO\LQSODFHV

FRQWDLQVFOD\EDOOV

DQGSDUWLQJVJUD\

RUDQJHDQGEURZQ

OHQWLFXODUVDQG\

FOD\IHUUXJLQRXV

VDQGVWRQH

3OLRFHQH

0LRFHQH

DTXLIHU

:LOO\LHOGPLOOLRQ

JDOORQVRIZDWHU

SHUGD\RUPRUH

SHUZHOO

:DWHULVORZLQWRWDO

GLVVROYHGVROLGV

FRQWDLQVLURQLQ

H[FHVVRIPLOOL

JUDPSHUOLWHUDQG

DFLGLF

0LRFHQH 0LRFHQH

6HULHV

XQGLIIHUHQWLDWHG

¥ 6DQGJUD\RUDQJH

DQGUHGYHU\ILQH

WRFRDUVHJUDLQHG

FRQWDLQVJUDYHOLQ

SODFHVJUD\WKLQ

EHGGHGWRPDVVLYH

VDQG\VLOW\FOD\
 $VVHVVPHQWRI:DWHU4XDOLW\&RQGLWLRQVLQWKH-%&RQYHUVH/DNH:DWHUVKHG0RELOH&RXQW\$ODEDPD¥

)LJXUH 0DMRUVRLODVVRFLDWLRQVLQWKH&RQYHUVH/DNHZDWHUVKHG$ODEDPD
1DWXUDO)DFWRUV 

inflow to and outflow from the lake determines the 

residence time of the water in the lake.

Converse Lake receives inflow from seven major 

tributaries that drain about three-fourths of the total 

watershed (fig. 1; table 1). Big Creek is the largest 

subbasin and drains 31.5 mi2

 at the Big Creek gaging 

station (site BIG, fig. 1) near Wilmer, Ala. Adjoining 

subbasins in the eastern part of the watershed are 

Juniper Creek (site JUN), Collins Creek (site COL), 

Crooked Creek (site CRO), and Hamilton Creek 

(site HAM; fig. 1). These subbasins have drainage 

areas ranging from 8.08 to 9.22 mi2

. Long Branch 

(site LON) and Boggy Branch (site BOG; fig. 1), 

located in the western part of the watershed, have 

smaller subbasins that each drain about 3 mi2

 (table 1). 

Streamflow data are critical in computing and 

interpreting nutrient loads and trends. A brief summary 

of streamflow conditions in the Converse Lake 

watershed for the study period, October 1990 to 

September 1998, is provided in table 3. Long and 

Boggy Branches (sites LON and BOG) had only 1 year 

of record; Collins and Juniper Creeks (sites COL and 

JUN) had 2 years of record. Big Creek, Crooked Creek, 

and Hamilton Creek (sites BIG, CRO, and HAM) had 

mean annual streamflows of 72.2, 19.4, and 

25.0 (ft3/s), respectively, for the study period. 

Computation of annual yields was used to normalize 

streamflow for the tributary drainage areas to allow for 

comparisons of streamflow per square mile. Hamilton 

Creek subbasin had the greatest yield of 

3.04 (ft3

/s)/mi2; Crooked and Big Creeks had yields of 

2.40 and 2.29 (ft3

/s)/mi2, respectively. 

Big Creek contributes about one-half of the 

gaged inflow to Converse Lake during average and 

above-average flow conditions, and Hamilton Creek 

contributes about 20 percent (Journey and others, 

1995). Hamilton Creek, however, has more sustained 

flows, and the proportion of its contribution to the total 

inflow increases as overall flow decreases. Crooked, 

Collins, and Juniper Creeks also contribute substantial 

inflow to the lake, especially during low-flow periods. 

Long and Boggy Branches seldom contribute more 

than 10 percent of the total inflow to the lake under all 

flow conditions (table 3). Downstream from the dam, 

Big Creek continues to flow to the south-southwest to 

its confluence with the Escatawpa River in Mississippi.

Streamflow frequency can be estimated by 

constructing a flow-duration curve for the stream. By 

definition, the flow-duration curve is a cumulativefrequency curve that shows the percentage of time a 

specific streamflow is equaled or exceeded during a 

given period. The shape of the flow-duration curve is a 

7DEOH 6WUHDPIORZFRQGLWLRQVLQVHOHFWHGWULEXWDULHVWR&RQYHUVH/DNH2FWREHUWR6HSWHPEHU

[mi2, square miles; ft3/s, cubic feet per second; —, not applicable]

6LWH

ODEHO

ILJ

6WDWLRQ

QXPEHU 6WDWLRQQDPH

'UDLQDJH

DUHD

PL



3HULRGRI

UHFRUG

6WUHDPIORZFKDUDFWHULVWLFVIW

V

0HDQ

DQQXDO



ZDWHU

\HDU



SHUFHQW

H[FHHGV



SHUFHQW

H[FHHGV



SHUFHQW

H[FHHGV

BIG 02479945 Big Creek at County Road 63 

near Wilmer, Ala.

31.5 1991–98 72.2a

a

Data published in Pearman, Stricklin, and Psinakis (1998).

94.1 147a 40a 22a

JUN 02479948 Juniper Creek at Glenwood 

Road near Fairview, Ala.

9.22 1991–92 17.7b

b

Data published in Pearman and others (1992). 

20.1 28b 14b 10b

COL 02479950 Collins Creek at Glenwood 

Road near Fairview, Ala.

8.54 1991–92 15.7b 18.1 24b 13b 9.2b

LON 02479955 Long Branch near Wilmer, 

Ala.

2.85 1991 — 6.76c

c

Data published in Pearman and others (1991).

— ——

BOG 02479960 Boggy Branch near Wilmer, 

Ala.

3.17 1991 — 9.43c — ——

CRO 02479980 Crooked Creek near 

Fairview, Ala.

8.08 1991–98 19.4a 21.8 29a 12a 8.4a

HAM 02480002 Hamilton Creek at Snow 

Road near Semmes, Ala.

8.22 1991–98 25.0a 24.5 33a 18a 13a

TOTAL 71.58 — — 196 — ——
 $VVHVVPHQWRI:DWHU4XDOLW\&RQGLWLRQVLQWKH-%&RQYHUVH/DNH:DWHUVKHG0RELOH&RXQW\$ODEDPD¥

reflection of the hydrologic and geologic 

characteristics of the stream’s watershed (Searcy, 

1959). A flow-duration curve that has a steep slope is 

indicative of a stream having highly variable flow 

derived largely from direct runoff (little or no groundwater contribution); a flat slope is indicative of 

sustained flow, a result of contributions from surfaceor ground-water storage. During dry periods, when 

streamflow is at a minimum, water discharging to 

streams and lakes is considered to be derived almost 

solely from ground water. 

Flow-duration curves were constructed from 

continuous streamflow record for the period October 

1990 to September 1998 for three gaged sites in the 

Converse Lake watershed—Big Creek (site BIG), 

Crooked Creek (site CRO), and Hamilton Creek 

(site HAM, figs. 1, 8). Because the drainage areas of 

the selected streams vary, the computed values were 

normalized to obtain unit-area discharge in cubic feet 

per second per square mile. Hamilton Creek had the 

greatest sustained streamflow of the selected sites, but 

flow duration at all sites indicated that ground water is 

an important contributor of water to Converse Lake and 

its tributaries during periods of no rainfall.

For this investigation, mean annual inflow was 

estimated for October 1990 to September 1998 based 

on streamflow data for Big Creek, Crooked Creek, and 

Hamilton Creek (sites BIG, CRO, and HAM; fig. 1). 

Because of limited streamflow record at the remaining 

four sites (table 3), streamflow data for these sites were 

not used in the calculation. Based on the 1991 water 

year in which streamflow data were available for all 

seven sites, Big Creek, Crooked Creek, and Hamilton 

Creek contributed 72 percent of the total annual inflow 

to the reservoir. The mean annual inflow to the 

reservoir for the 1990–98 period was estimated by 

combining the mean annual streamflow for Big Creek, 

Crooked Creek, and Hamilton Creek (117 ft3

/s) and 

multiplying by 1.39 (the reciprocal of 72 percent). The 

product (163 ft3

/s) was converted to acre-ft by 

multiplying by 724 acre-ft per year to obtain a mean 

annual inflow to the reservoir of about 118,000 acre-ft. 

The residence time of water in a reservoir is calculated 

by dividing the volume of the reservoir (in the case of 

)LJXUH 6WUHDPIORZGXUDWLRQFXUYHVIRU%LJ&UHHN&URRNHG&UHHNDQG+DPLOWRQ&UHHNLQWKH

&RQYHUVH/DNHZDWHUVKHG¥
&XOWXUDO)DFWRUV 

Converse Lake, 52,000 acre-ft) by the mean annual 

inflow to the reservoir. The residence time for water in 

Converse Lake was calculated to be 0.44 year or 

160 days (table 2).

&XOWXUDO)DFWRUV

Other factors influencing the water quality of 

Converse Lake are cultural factors derived from human 

activities. Cultural factors in the watershed commonly 

are linked to natural factors, such as land use and land 

cover. For example, the degree to which agricultural 

activities within a given watershed will affect the water 

quality in the watershed depends on several natural 

factors, such as amount of precipitation, type and 

thickness of soils, land-surface slope, and the amount 

of vegetation left to form a buffer between the 

developed land and water bodies in the watershed. 

The rural countryside of the Converse Lake 

watershed is covered mainly by forests of evergreen, 

deciduous, and mixed deciduous/evergreen trees 

(64 percent of the land use in the watershed) (figs. 9, 

10). Timber is harvested usually by clear-cutting 

techniques, especially in the northern part of the 

watershed. Agriculture accounts for about 31 percent 

of the land use in the watershed and is separated into 

two categories—pasture land and hay (18 percent) and 

row crops or plant nurseries (13 percent). Residential 

and commercial development account for only 

1 percent of the total land use in the watershed. Most of 

the residential land use in the watershed is categorized 

as low-intensity development, which means that 

impervious areas and construction materials account 

for 30–80 percent of the total area, and vegetation 

(trees, other grasses) accounts for the remaining 

20–70 percent. 

Land use varies within the tributary subbasins of 

the Converse Lake watershed (table 4). Nearly threefourths of the Big Creek subbasin is covered by 

forested land. The remaining one-fourth is mainly 

agricultural land. The percentage of agricultural land 

use (row crops and pasture/hay) is greatest in the 

Crooked Creek subbasin, accounting for over 

42 percent of the subbasin. Much of the land 

designated as row crops in the Crooked Creek subbasin 

actually is plant nurseries. The percentage of 

residential area (3.4 percent) in Crooked Creek is 

second only to Hamilton Creek (3.9 percent). The 

Hamilton Creek subbasin also has the greatest wetland 

coverage (5.3 percent) and relatively high agricultural 

land use (36.1 percent). 

 Previous work conducted by Auburn University 

relied on Landsat Thematic Mapper satellite images for 

1984, 1992, and 1995 to identify changes in land use in 

the Converse Lake watershed over time (Reutebuch 

and others, 1997). The most dramatic change was a net 

regrowth of forest cover from 1984 to 1992, followed 

by a net loss of forest in 1995. Minimal change was 

observed in agricultural practices (grasslands and row 

crops). It should be noted, however, this method of 

land-use identification works best for large-scale 

changes in land use. Small-scale changes may be 

missed, as indicated by field verification that identified 

the presence of new homes and greenhouses in the 

Converse Lake watershed that were at a scale below the 

30-m resolution of the satellite data.

Point-source discharges from industrial activity 

are monitored by State and Federal regulatory 

agencies. The USEPA Storage and Retrieval System 

(STORET) database contains all permitted pointsource locations and descriptions in the United States. 

This database was queried to identify point sources in 

the Converse Lake watershed (fig. 11). No Toxic 

Release Inventory (TRI) or Superfund (CERCLA) sites 

were present in the watershed during 1990–98. Two 

hazardous- and solid-waste sites were identified—one 

in the Hamilton Creek subbasin and the other in the 

Juniper Creek subbasin (fig. 11). No contaminant 

releases (air, water, ground water) were reported from 

1987 to 1995. Two permit compliance system (PCS) 

sites also were listed—one is permitted to discharge to 

the ground water near an unnamed tributary in the 

Collins Creek subbasin, and the other is permitted to 

discharge to the ground water near the headwaters of 

Hamilton Creek. No PCS discharges were reported 

between 1991 and 1995. 

Plant nurseries ranging in size from less than an 

acre to over 300 acres increased in number and size in 

Crooked Creek and Hamilton Creek subbasins during 

the study period (fig. 11). The MRLC coverage does 

not distinguish nurseries from row crops and pastures. 

The Mobile County Extension Service of the Natural 

Resource Conservation Service (NRCS) provided 

location and acreage data for plant nurseries within the 

Converse Lake watershed that were used to develop a 

point coverage. The coverage shown in figure 11 

demonstrates the concentration of plant nurseries in the 

Crooked Creek and, to a lesser extent, Hamilton Creek 

subbasins.
 $VVHVVPHQWRI:DWHU4XDOLW\&RQGLWLRQVLQWKH-%&RQYHUVH/DNH:DWHUVKHG0RELOH&RXQW\$ODEDPD¥

)LJXUH *HQHUDOODQGXVHVIRUWKH&RQYHUVH/DNHZDWHUVKHG
&XOWXUDO)DFWRUV 

)LJXUH /DQGXVHSHUFHQWDJHVLQWKH&RQYHUVH/DNHZDWHUVKHG

&URSODQGVZHWODQGVDQGDUHVLGHQWLDODUHDLQWKH&RQYHUVH/DNH

ZDWHUVKHGSKRWRJUDSKVE\:LOO60RRW\86*HRORJLFDO6XUYH\


$VVHVVPHQWRI:DWHU4XDOLW\&RQGLWLRQVLQWKH-%&RQYHUVH/DNH:DWHUVKHG0RELOH&RXQW\$ODEDPD¥

7DEOH /DQGXVHLQVHOHFWHGVXEEDVLQVRIWKH&RQYHUVH/DNHZDWHUVKHGLQDFUHVDQGSHUFHQWDFUHDJHRIVXEEDVLQIURP0XOWL5HVROXWLR

6XEEDVLQ :RRG\ ZHWODQGV (PHUJHQW KHUEDFHRXV ZHWODQGV

+LJK

LQWHQVLW\

UHVLGHQWLDO

LQGXVWULDO

WUDQVSRUWDWLRQ

/RZ

LQWHQVLW\

UHVLGHQWLDO

+LJK

LQWHQVLW\

UHVLGHQWLDO

'HFLGXRXV

IRUHVW

0L[HG

IRUHVW

(YHUJUHHQ

IRUHVW

3DVWXUH

KD\

2WKHU

JUDVVHV

F

05/&ODQGXVHLQDFUHV

Big Creek 154 7.6 6.8 0.7 0 1,335 6,744 6,387 2,540 0 2Juniper Creek 42.0 5.1 2.8 8.9 0 362 1,613 1,750 1,181 60 Collins Creek .0 0 41.4 69.1 5.8 372 1,278 1,576 927 207 Long Branch 3.0 0 7.1 12.2 .7 103 514 619 404 0 Boggy Branch 7.5 1.1 0.9 0 0 140 505 491 513 0 Unmonitored 559 64.7 7.6 16.4 1.0 727 3,241 7,972 2,668 60 2Hamilton Creek 260 17.1 8.5 178 15.5 222 1,121 1,400 1,081 62 Crooked Creek 56.0 2.7 34.7 141 9.9 215 1,048 1,227 1,309 277 

05/&ODQGXVHLQSHUFHQWDFUHDJHRIVXEEDVLQ

Big Creek 0.78 0.04 0.03 0 0 6.7 34 32 13 0 Juniper Creek .69 .08 .05 .15 0 6.0 27 29 20 .99 Collins Creek 0 0 .76 1.3 .11 6.8 24 29 17 3.8 Long Branch .16 0 .39 .66 .04 5.6 28 34 22 0 Boggy Branch .38 .06 .04 0 0 7.1 26 25 26 0 Unmonitored 3.1 .36 .04 .09 .01 4.1 18 45 15 .34 Hamilton Creek 4.9 .33 .16 3.4 .30 4.2 21 27 21 1.2 Crooked Creek 1.0 .05 .64 2.6 .18 4.0 19 23 24 5.1 
&XOWXUDO)DFWRUV 

)LJXUH /RFDWLRQVRISHUPLWWHGSRLQWVRXUFHVDQGSODQWQXUVHULHVLQWKH&RQYHUVH/DNHZDWHUVKHG
 $VVHVVPHQWRI:DWHU4XDOLW\&RQGLWLRQVLQWKH-%&RQYHUVH/DNH:DWHUVKHG0RELOH&RXQW\$ODEDPD¥

%$6,&:$7(5&+(0,675<

The major dissolved constituents that give water 

its characteristic chemistry are cations (positively 

charged ions) of calcium, magnesium, sodium, and 

potassium; and anions (negatively charged ions) of 

chloride, sulfate, and nitrate. Dissolved silica also is a 

major constituent of most waters, especially in 

sandstone bedrock and acidic, deeply weathered soils 

such as those in the Converse Lake watershed. 

Concentrations of major dissolved ions generally are 

measured in parts per million or milligrams per liter. 

The chemistry of natural surface waters is the 

result of interactions between precipitation, ground 

water, rocks, and soils near the Earth’s surface. Human 

activity, however, can alter naturally occurring water 

chemistry by contributing additional ions, most 

commonly sodium and chloride. While basic cations 

and anions are not considered contaminants, elevated 

ion concentrations occurring near human activities may 

provide a clue to potential sources of more problematic 

contaminants (nutrients, trace elements, synthetic 

organic compounds). 

The term “trace elements” relates to constituents 

in water at levels that generally are measured in parts 

per billion or micrograms per liter. Trace elements 

include metals, such as beryllium, cadmium, 

chromium, copper, lead, mercury, and nickel; and 

nonmetals, such as arsenic. These listed trace elements 

are considered priority pollutants by the USEPA 

because of their potential harm to humans and aquatic 

health at elevated concentrations. Iron and manganese 

are commonly occurring trace elements that are 

nonpriority pollutants. All trace elements can be 

derived from natural sources, such as rocks, soils, and 

ground water, as well as anthropogenic sources. 

Other measures of the physical and chemical 

nature of water provide further information to assess 

the quality of the water. Specific conductance, water 

temperature, dissolved-oxygen concentration, and pH 

are important physical and chemical factors when 

assessing water-quality conditions. 

:DWHU4XDOLW\$QDO\VLV0HWKRGVDQG$SSURDFK

Water-quality samples have been collected 

quarterly since 1991 at the tributary sites (sites BIG, 

JUN, COL, LON, BOG, CRO, and HAM; fig. 1) and in 

the lake at the pump station (site LHAM, fig. 1). Waterquality samples were collected at the tributary sites 

using a multiple vertical technique; a DH-81 sampler 

was used in wadeable water and a weighted-bottle 

sampler was used in unwadeable water. The lowgradient, slow flowing tributaries prevented the 

collection of true isokinetic samples (Wilde and others, 

1999a). Water-quality samples were processed in the 

field according to procedures described in Wilde and 

others (1999b), and shipped to the USGS Quality Water 

Service Unit Laboratory in Ocala, Florida, for analysis. 

The samples were analyzed for major ions (calcium, 

magnesium, sodium, potassium, nitrate, chloride, 

sulfate, silica), and for iron, manganese, and boron. The 

analytical results are stored in the USGS National 

Water Information System (NWIS) database. 

Streamflow gages provided continuous streamflow 

record at three tributary sites during the study period 

(sites BIG, CRO, and HAM; fig. 1). Instantaneous 

streamflow, water temperature, dissolved oxygen 

(concentration and percent saturation), pH, alkalinity, 

and specific conductance were measured in the field at 

the time of sampling, according to techniques 

described in Wilde and Radtke (1998).

The chemical data are summarized statistically 

for this report in appendix 1. Computed statistics 

include maximum, minimum, mean, and the 95th, 75th, 

50th, 25th, and 5th percentiles. The nth percentile is a 

data value that exceeds no more than n percent of the 

data and is exceeded by no more than 100 minus 

n percent of the data (Helsel and Hirsch, 1992). These 

statistics were used to construct boxplots of 

concentration data for constituents of interest. A 

“boxplot is a concise graphical summary of the data 

distribution, displaying the median, interquartile range 

(75th–25th percentile), skewness, and extreme values” 

(Helsel, 1987). The median values (50th percentile of 

the measured values) were used to compare between 

tributary subbasins and between tributary sites and the 

lakes to identify major differences in water chemistry. 

The data were compared graphically by using radial 

plots of the major ion concentrations converted to 

milliequivalents per liter. The relation between pH 

levels and land use (1992 MRLC land-use categories) 

in the watershed was determined by computing 

Spearman rho correlation coefficients and probability 

values to identify significant relations between the 

median pH and the percentage of land-use category in 

the watershed. 
%DVLF:DWHU&KHPLVWU\ 

5HVXOWVRI:DWHU4XDOLW\$QDO\VLV

The waters in Converse Lake and its tributaries 

have low pH and low specific conductance, which is 

typical of waters in humid climates that drain highly 

resistant sands and gravels (Hem, 1985; Drever, 1988; 

fig. 12). The basic chemistry of surface water in the 

Converse Lake watershed varies slightly among 

subbasins but basically is a calcium-sodium-chloridedominated water. 

The presence of electrically charged dissolved 

constituents in water makes the water conductive; 

therefore, specific conductivity provides an estimate of 

the total dissolved constituents in water. In natural 

freshwater systems, specific conductance values near 

50 μS/cm are considered low and indicative of 

watersheds draining resistant rocks (Drever, 1988). In 

the Converse Lake watershed, median specific 

conductance values ranged from 23 (site COL) to 

43 μS/cm (site LON) during the study period (fig. 12; 

appendix 1). 

Water is considered saturated with oxygen when 

its concentration is exactly equal to the expected 

solubility concentration at a particular temperature and 

air pressure. Commonly, the dissolved-oxygen 

concentration in water is measured in milligrams per 

liter, but a saturation percentage—percent ratio of the 

dissolved-oxygen concentration measured in the water 

to the saturated dissolved-oxygen concentration based 

on oxygen solubility—also can be used. 

Photosynthesis from aquatic plants and reaeration from 

streamflow can raise the dissolved-oxygen 

concentration above saturated levels in natural waters, 

whereas respiration and bacterial decay of organic 

matter in these waters can reduce the dissolved-oxygen 

concentration below saturated levels. The degree of 

influence of these processes on dissolved-oxygen 

levels varies daily and seasonally. Photosynthesis 

dominates during the day because it requires sunlight; 

respiration dominates at night. Cooler temperatures in 

the winter allow for greater solubility of dissolved 

oxygen (solubility increases as temperature decreases), 

and increased streamflow during wet periods provides 

greater reaeration. 

The ADEM criterion for minimum dissolvedoxygen concentration is 5 mg/L for the water-use 

classification in the Converse Lake watershed 

(Alabama Department of Environmental Management, 

1994a). During this investigation, all tributary sites in 

the watershed had minimum dissolved-oxygen 

concentrations above 5 mg/L except for site BOG 

(fig. 1), which had a minimum dissolved-oxygen 

concentration of 3.7 mg/L. Median dissolved-oxygen 

concentrations at tributary sites ranged from 6.9 mg/L 

(site BOG) to 8.6 mg/L (sites JUN and LON), and 

median saturation percentages ranged from 74 to 

94 percent. 

Reservoirs, such as Converse Lake, stratify 

thermally during the late summer months. 

Stratification prevents mixing of the warmer, upper 

layer of water (epilimnion) with the cooler, denser, 

lower layer of water (hypolimnion). Because of the 

lack of mixing, solubility and photosynthetic processes 

in the upper layer, which produce dissolved oxygen, are 

unable to replenish the dissolved oxygen in the lower 

layer, resulting in a depletion of dissolved oxygen in 

the lower layer by respiration and decay of organic 

matter. Converse Lake typically becomes strongly 

stratified during August and September, and dissolvedoxygen concentrations generally fall below 1 mg/L at 

depths greater than 20 ft (Journey and others, 1995; 

Bayne and others, 1998). 

0DMRU,RQV

Differences in the major ionic composition 

among subbasins were evaluated by constructing radial 

plots of median ion concentrations, in milliequivalents 

per liter, for the seven tributary sites and the two lake 

sites (fig. 13). These plots were used to illustrate 

variations in water composition by visually comparing 

the shape of the plots (sites with similar water 

compositions exhibit similar shapes) and the size of the 

plots (sites with the greater ionic concentrations exhibit 

larger sizes). The diagramming software plots a 

polygon that represents the major anion (sulfate, 

chloride, nitrate, and bicarbonate) and major cation 

(calcium, magnesium, sodium, and potassium) 

concentrations as a point on individual axes. 

Big Creek had one of the most dilute and 

strongly sodium-chloride types of ionic compositions 

of all the sites (fig. 13). All other sites exhibited a 

greater calcium-bicarbonate component than Big 

Creek. Boggy Branch had a similar ionic composition 

to Collins Creek, except for a much greater chloride 

and magnesium component. Long Branch and Crooked 

Creek had ionic compositions with the greatest overall 

concentrations and strongest calcium-bicarbonate 

component. The ionic composition of Hamilton Creek 

was similar to Crooked Creek, but Hamilton Creek had 

a greater sodium-chloride component and less 

magnesium. The ionic composition at the lake sites 
 $VVHVVPHQWRI:DWHU4XDOLW\&RQGLWLRQVLQWKH-%&RQYHUVH/DNH:DWHUVKHG0RELOH&RXQW\$ODEDPD¥

)LJXUH $S+DQG%VSHFLILFFRQGXFWDQFHYDOXHVDWVHOHFWHGVLWHVLQWKH&RQYHUVH/DNHZDWHUVKHG¥
%DVLF:DWHU&KHPLVWU\ 

)LJXUH 5DGLDOSORWVRIPHGLDQLRQFRQFHQWUDWLRQVLQPLOOLHTXLYDOHQWVSHUOLWHUDW$+DPLOWRQ&UHHN

%&URRNHG&UHHN&%RJJ\%UDQFK'&RQYHUVH/DNH(/RQJ%UDQFK)-XQLSHU&UHHN*&ROOLQV&UHHN

DQG+%LJ&UHHNLQWKH&RQYHUVH/DNHZDWHUVKHG¥
 $VVHVVPHQWRI:DWHU4XDOLW\&RQGLWLRQVLQWKH-%&RQYHUVH/DNH:DWHUVKHG0RELOH&RXQW\$ODEDPD¥

appeared to be most like the composition of tributary 

waters in the central and southern parts of the 

watershed (Long Branch, Crooked Creek, and 

Hamilton Creek) and less similar to sites in the 

headwaters portion of the watershed. This similarity 

was especially evident in the proportion of cations 

(calcium, magnesium, sodium). The sulfate component 

of the overall ionic composition was minimal at all 

sites.

The chemistry of streamwater varies with flow 

conditions because of changes in the flow pathways in 

the watershed. During and immediately after a storm, 

the water in a stream is a mixture of surface runoff, 

shallow subsurface flow through the soil zone, and 

ground-water discharge. During base-flow conditions, 

streamwater is predominantly ground-water discharge. 

Ion concentrations during periods of base flow and 

high streamflow were plotted for Big Creek (site BIG, 

fig. 1), Hamilton Creek (site HAM), and Crooked 

Creek (site CRO) to identify changes in ionic 

composition with flow conditions (fig. 14). Big Creek 

exhibited effects of dilution during high streamflow 

conditions. The greatest nitrate and bicarbonate 

concentrations were during base flow at this site. 

Hamilton Creek exhibited slight dilution effects on 

silica and chloride, and an increase in the calciumbicarbonate component during high streamflow 

conditions. Crooked Creek had a similar 

response—decreased nitrate and increased calciumbicarbonate during high streamflow conditions as well 

as increased chloride. 

In summary, no dramatic differences in ionic 

composition were observed among tributary and lake 

sites. The greatest difference was observed at Big 

Creek, which had proportionally lower calciumbicarbonate component than the other sites. 

Bicarbonate and nitrate fractions of the ionic 

composition in Big Creek were highest during baseflow periods, suggesting a ground-water source. 

Runoff and shallow soil-zone flow during high 

streamflow conditions contributed more dilute waters, 

causing a decrease in ionic concentration at Big Creek. 

Median ion concentrations of calcium and bicarbonate 

in Crooked Creek and Hamilton Creek depicted an 

increase in overall ion concentrations compared to Big 

Creek. The calcium-bicarbonate component of these 

increased ion concentrations occurred during high 

streamflow periods, suggesting ion introduction to the 

streamwater from runoff and soil-zone flushing. Higher 

concentrations of nitrate were evident during base flow 

in both Crooked and Hamilton Creeks, suggesting a 

ground-water source.

S+DQG$ONDOLQLW\

Hydrogen ions contribute acidity in water. 

Although hydrogen-ion (H+) concentrations in water 

can be measured in milligrams per liter, the extremely 

low hydrogen-ion concentrations in natural aquatic 

systems require measurement and reporting in 

logarithmic units. The term “pH” represents the 

negative base-10 log of the hydrogen-ion concentration 

or, specifically, the activity. The pH of natural systems 

generally ranges from 6 to about 9, representing 

hydrogen-ion concentrations that range from 1 x 10 -6

to 1 x 10 -9 milligrams per liter (trace constituents). 

The ability or capacity of water to absorb hydrogen 

ions (neutralize acid) without a substantial change in 

pH is called the acid-neutralizing capacity (ANC) of 

the water. The ANC is a measure of the alkalinity of 

unfiltered water. 

When the pH of aquatic systems falls below 4 or 

5, the diversity of the endemic aquatic species (plants 

and animals) can be severely restricted. Some 

influences related to human activities that can have an 

adverse effect on the pH of surface water are 

commercial and industrial discharges, urban runoff, 

acidic drainage from mines, and acid rain. The ADEM 

established a pH range of 6 to 8.5 to prevent aquaticspecies diversity restrictions in most natural water 

systems of the State (Alabama Department of 

Environmental Management, 2000). If, however, the 

pH range naturally falls below the criteria range, as in 

the case of waters draining resistant sandstone and 

granitic bedrocks or deeply weathered soils, the 

naturally occurring range is acceptable. 

Although all sites in the Converse Lake 

watershed had pH levels that periodically fell below the 

ADEM lower level criterion of 6, only two streams had 

median pH levels below that level—sites BIG and 

BOG (fig. 1) had median pH values of 5.6 and 5.9, 

respectively. The remaining tributary and lake sites had 

median pH values that were within the criteria range 

(appendix 1; fig. 12). The highest median pH levels 

were recorded at tributary sites LON and CRO and at 

lake sites LCRO and LHAM, where the median pH 

levels were 6.3, 6.4, 6.2, and 6.2, respectively. 

Alkalinity and ANCs corresponded well with pH 

levels. Site BIG had the lowest median alkalinity 

(2 mg/L), and sites LON and CRO had the highest 
%DVLF:DWHU&KHPLVWU\ 

)LJXUH 5DGLDOSORWVRILRQLFFRQFHQWUDWLRQVLQPLOOLHTXLYDOHQWVSHUOLWHUDW%LJ&UHHN+DPLOWRQ&UHHNDQG&URRNHG&UHHNGXULQJKLJK

VWUHDPIORZFRQGLWLRQV$&DQG(UHVSHFWLYHO\DQGEDVHIORZFRQGLWLRQV%'DQG)UHVSHFWLYHO\LQWKH&RQYHUVH/DNHZDWHUVKHG

¥
 $VVHVVPHQWRI:DWHU4XDOLW\&RQGLWLRQVLQWKH-%&RQYHUVH/DNH:DWHUVKHG0RELOH&RXQW\$ODEDPD¥

alkalinity (7 mg/L). Median ANCs ranged from 

3 (site BIG) to 8 mg/L (sites LON, CRO).

Percentages of land in each land-use category 

were computed for each subbasin in the 1992 MRLC 

coverage. The computed land-use percentages were 

correlated with median pH levels and ANCs for the 

tributary subbasins to determine if the more acidic pH 

levels were related to natural (forested) or 

anthropogenic (agricultural, residential) conditions in 

the watershed (table 5; fig. 15). Negative correlation 

coefficients indicate an inverse relation between land 

use and the median pH or ANC (when one increases, 

7DEOH 6SHDUPDQUKRFRUUHODWLRQFRHIILFLHQWVIRUSHUFHQWDJHRIODQGXVHDQGPHGLDQOHYHOVRIS+DFLGQHXWUDOL]LQJFDSDFLW\DQG

VSHFLILFFRQGXFWDQFHLQWKH&RQYHUVH/DNHZDWHUVKHG

[MRLC, multi-resolution land characteristic. Coefficients that are statistically significant are bold (p-value < 0.05)]

05/&ODQGXVHFDWHJRU\

:DWHUTXDOLW\FRQVWLWXHQW

S+ $FLGQHXWUDOL]LQJ

FDSDFLW\

6SHFLILF

FRQGXFWDQFH

Evergreen forest -0.1261 -0.2245 -0.7186

Deciduous forest -0.6126 -0.7485 -0.6786

Mixed forest -0.5225 -0.5052 -0.2143

Transitional -0.2883 -0.6175 -0.7143

Row crops 0.3964 0.2994 0

Pasture and hay 0.3434 0.6175 0.7143

High-intensity residential 0.6171 0.6602 0.3706

Low-intensity residential 0.6727 0.6797 0.3604

Industrial/commercial/high-intensity residential 0.8829 0.6175 0.1786

Other grasses 0.6171 0.3690 -0.0371

Wetlands -0.1261 0.1497 0.2857

)LJXUH &RUUHODWLRQEHWZHHQODQGXVHFDWHJRU\DQGPHGLDQS+DQGDFLGQHXWUDOL]LQJFDSDFLW\LQWULEXWDU\VXEEDVLQVLQWKH&RQYHUVH

/DNHZDWHUVKHG
1XWULHQW/RDGLQJDQG7URSKLF5HVSRQVH 

the other decreases); positive coefficients indicate 

direct relation (when one increases, the other also 

increases). No statistically significant relation was 

found among the agricultural land-use categories of 

row crops, pasture and hay, residential land use, other 

grasses (parks, fields), and forested land. The only 

significant relation (p-value < 0.05) was between pH 

and commercial, industrial, and residential land 

(table 5). This relation was positive, suggesting the 

greater the amount of developed land, the less acidic 

the pH. 

In summary, Big Creek (site BIG) and Boggy 

Branch (site BOG) had median pH levels below the 

ADEM criterion of 6 and relatively low ANCs. 

Statistical correlations indicate that the greater the 

amount of commercial, industrial, and residential 

development (human influenced), the greater the 

tendency for the streamwater to have a more neutral 

median pH and a greater capacity to neutralize acid. 

This correlation, in conjunction with the environmental 

factors of resistant rock types and acidic soil in the 

watershed, provides a strong indication that low pH and 

low ANCs are of natural origin, not anthropogenic. In 

1996, the ADEM 305(b) Water-Quality Report to 

Congress stated that Converse Lake, listed as Big 

Creek Lake, had pH values that fell below the criteria 

range of 6 to 8, but also stated that the “Low pH values 

measured in Big Creek...are determined to be of natural 

origin and are considered unlikely to cause adverse 

impacts” (Alabama Department of Environmental 

Management, 1999).

7UDFH(OHPHQWV

Iron and manganese are two trace elements that 

were monitored quarterly in the Converse Lake 

watershed. Water samples were analyzed for both total 

and dissolved species. These elements adversely affect 

the taste and odor of water; therefore, the ADEM has 

set secondary standards for acceptable levels of less 

than 300 μg/L for total iron and 50 μg/L for total 

manganese in drinking water, after filtration and 

treatment (Alabama Department of Environmental 

Management, 2000). 

Converse Lake and its tributaries had median 

total iron concentrations that exceeded the National 

secondary drinking-water standard of 300 μg/L 

(fig. 16; appendix 1). However, this raw water would 

be filtered and treated prior to distribution in the 

drinking-water system, resulting in iron concentrations 

below these limits. Median dissolved iron 

concentrations generally were one-half to one-third of 

the total iron value. The highest median concentrations 

of total iron were 940 and 725 μg/L in Boggy Branch 

(site BOG) and Crooked Creek (site CRO), 

respectively; the lowest median concentrations of 

315 and 320 μg/L were in the lake sites LCRO and 

LHAM, respectively. Boggy Branch was the only site 

with a median total manganese concentration (79 μg/L) 

that exceeded the secondary standard of 50 μg/L. 

Collins Creek (site COL) and the lake site at the pump 

station (site LHAM) had the lowest median 

concentrations of total manganese (23 and 20 μg/L, 

respectively). 

1875,(17/2$',1*$1'7523+,&5(63216(

The amount of biologically available nutrients, 

mainly phosphorus and nitrogen compounds, 

contributes to the trophic state of a water body. Nutrient 

enrichment accelerates the process of eutrophication, 

which results in excessive growth of algae (algal 

blooms) and other aquatic plants. Nuisance algal 

production causes a variety of associated water-quality 

problems, including increased biochemical oxygen 

demand, extreme vertical changes in dissolved-oxygen 

concentrations (from oversaturated to depleted), high 

turbidity, unpleasant odors and tastes, and blockages of 

water-purification systems at treatment facilities. 

Globally, the process of eutrophication has increased 

rapidly as a result of human activities, including runoff 

(nonpoint) from agricultural areas and the discharge of 

industrial wastes and treated municipal sewage, that 

contribute excess nutrients to streams, rivers, lakes, and 

estuaries.

The relation between the annual input of 

nutrients and the in-lake phosphorus and nitrogen 

concentrations is central to understanding and 

managing eutrophication problems. This complex 

relation involves the interaction of physical and 

chemical processes and biological responses, requiring 

a distinction between trophic potential and trophic 

response. The trophic potential of a reservoir is the 

carrying or assimilating capacity of the ecosystem, and 

is a function of physical and chemical properties, such 

as nutrient concentrations, light penetration, climate, 

and hydraulic regime. The trophic response of a 

reservoir refers to the amount, type, and rate of biomass 

production and the water-quality variations that occur 

as a result of nutrient inputs. In order to predict or 

monitor the trophic response of a reservoir and its 
 $VVHVVPHQWRI:DWHU4XDOLW\&RQGLWLRQVLQWKH-%&RQYHUVH/DNH:DWHUVKHG0RELOH&RXQW\$ODEDPD¥

)LJXUH %R[SORWVRIWRWDODQGGLVVROYHGLURQDQGPDQJDQHVHFRQFHQWUDWLRQVDWVHOHFWHGVLWHVLQWKH&RQYHUVH/DNHZDWHUVKHG¥
1XWULHQW/RDGLQJDQG7URSKLF5HVSRQVH 

associated water-quality changes, easily measured 

trophic potential factors (nutrient concentration, 

inflow) must be correlated with the trophic response 

variables (transparency, chlorophyll, hypolimnetic 

dissolved oxygen).

 An index that estimates the trophic state can be 

computed from empirically derived equations 

determined from trophic response and trophic potential 

data from different lake systems. One of the most 

commonly used indices is Carlson’s Trophic State 

Index (TSI), which is based on transparency, 

phosphorus concentrations, and chlorophyll a levels in 

a lake during the summer months (Carlson, 1977). 

Chlorophyll a is a pigment found in algae, and is 

considered an estimate of the amount of algae present 

in the water. Greater algal production generally is 

related to enrichment of lake water with plant nutrients, 

such as nitrogen and phosphorus. A TSI value of less 

than 40 is indicative of oligotrophic or nutrient-poor 

conditions (table 6). A TSI value of 40 to 50 is 

indicative of mesotrophic or nutrient-balanced 

conditions. A TSI value of 50 to 70 is indicative of 

eutrophic or nutrient-enriched conditions. Eutrophic 

conditions in a lake can lead to a variety of waterquality problems, including unpleasant tastes and 

odors, depletion of dissolved oxygen (anoxia), and 

nuisance algal blooms. A TSI value above 70 indicates 

hypertrophic or extremely nutrient-rich conditions. In 

hypertrophic conditions, eutrophic water-quality 

problems become more pronounced, algal blooms are 

more common, and fish communities become 

dominated by bottom dwellers.

The results of ADEM’s Reservoir Water Quality 

Monitoring Program were reported in the Alabama 

305(b) Water-Quality Reports to Congress (Alabama 

Department of Environmental Management, 1996, 

1999). More than two-thirds of the lakes that were 

assessed in Alabama were classified as eutrophic. In 

7DEOH 3RWHQWLDOFKDQJHVLQODNHFKDUDFWHULVWLFVUHODWHGWRWURSKLFVWDWHPRGLILHGIURP5DVWDQG/HH

[<, less than; >, greater than]

7URSKLFVWDWHLQGH[D

a

Carlson, 1977.

7URSKLFVWDWH

FODVVLILFDWLRQ 3RWHQWLDOFKDQJHVLQODNHFKDUDFWHULVWLFV

< 30 Oligotrophic Clear water, oxygen in hypolimnion (deepest part of lake) year round. Sparse 

macrophyte (rooted aquatic plants) growth. Many algal species but low 

production.

30–40 Hypolimnion of shallower lakes becomes anoxic (lacking in oxygen).

40–50 Mesotrophic Water moderately clear but increasing probability of anoxic hypolimnion 

during summer. Increased iron and manganese levels evident during the 

summer months. 

50–60 Eutrophic Anoxic hypolimnion. Greater potential for iron and manganese, taste and 

odor problems. Increase in macrophyte growth. Algal species become less 

diverse. Surface-dwelling warm-water fish dominate, such as perch and 

bass, but bottom-dwellers, such as catfish and carp, are present.

60–70 Dominant algal groups change from greens and diatoms to blue-greens; algal 

scums and macrophyte problems.

> 70 Hypertrophic Light limited due to lack of transparency and high turbidity. Dense algae and 

macrophyte growth. Bottom-dwelling fish, such as catfish and carp, dominate.
 $VVHVVPHQWRI:DWHU4XDOLW\&RQGLWLRQVLQWKH-%&RQYHUVH/DNH:DWHUVKHG0RELOH&RXQW\$ODEDPD¥

the 305(b) report, concern was expressed over the 

trophic state of Converse Lake, listed by its former 

name, Big Creek Lake. Although Converse Lake was 

considered stable and supportive of both its designated 

uses (aquatic life and water supply), a noticeable 

increase in the trophic state condition of Converse Lake 

was reported. 

Defining the exact concentration of nitrogen or 

phosphorus that causes nutrient enrichment and an 

associated trophic response in a water body is difficult. 

The USEPA developed guidelines in 1975 for nutrient, 

chlorophyll a, and hypolimnetic dissolved-oxygen 

levels that can be used for trophic state determination 

as part of the National Eutrophication Survey 

(Gakstatter and others, 1975; table 7). The guidelines 

were developed from data collected at 96 lakes in the 

United States. 

As part of a global effort by the Organization for 

Economic Cooperation and Development (OECD) 

project, data were collected and the relation between 

nutrient load and a lake’s trophic response was 

quantified. The project consisted of four regional 

studies—Alpine, Nordic, Reservoir, and North 

American. The OECD index was developed based on 

the average value for each parameter for each trophic 

state. The results were summarized using a statistical 

approach to quantify the ranges of several parameters 

within the three trophic state conditions (Vollenweider 

and Kerekes, 1980; table 8). The results of the OECD 

study emphasized that lakes can have similar nutrient 

7DEOH 1DWLRQDO(XWURSKLFDWLRQ6XUYH\JXLGHOLQHVIRUWURSKLFVWDWHGHWHUPLQDWLRQPRGLILHGIURP*DNVWDWWHUDQGRWKHUV

[mg/L, milligram per liter; <, less than; >, greater than; μg/L, microgram per liter; m, meter]

3DUDPHWHU 2OLJRWURSKLF 0HVRWURSKLF (XWURSKLF

Total phosphorus (mg/L) < 0.01 0.01–0.02 > 0.02

Chlorophyll a (μg/L) < 4 4–10 > 10

Secchi depth (m) > 3.7 2.0–3.7 < 2.0

Hypolimnetic dissolved oxygen

(percent saturation)

> 80 10–80 < 10

7DEOH 2UJDQL]DWLRQIRU(FRQRPLF&RRSHUDWLRQDQG'HYHORSPHQWLQGLFHVIRUWURSKLFVWDWHGHWHUPLQDWLRQEDVHGRQVFLHQWLILFRSLQLRQ

IURP9ROOHQZHLGHUDQG.HUHNHV

[mg/L, milligram per liter; μg/L, microgram per liter; m, meter]

3DUDPHWHU

2OLJRWURSKLF 0HVRWURSKLF (XWURSKLF

*HRPHWULF

PHDQ 5DQJH *HRPHWULFPHDQ 5DQJH *HRPHWULFPHDQ 5DQJH

Total phosphorus

(mg/L)

0.008 0.003–0.018 0.027 0.011–0.096 0.084 0.016–0.39

Total nitrogen

(mg/L)

0.66 0.31–1.60 0.75 0.36–1.40 1.9 0.39–6.1

Chlorophyll a

(μg/L)

1.7 0.3–4.5 4.7 3–11 14 2.7–78

Peak chlorophyll a

(μg/L)

4.2a

a

This value is an arithmetic mean, not a geometric mean.

1.3–11 16a 5–50 43a 10–280

Secchi depth

(m)

9.9 5.4–28 4.2 1.5–8.1 2.4 0.8–7.0
1XWULHQW$QDO\VLV0HWKRGVDQG$SSURDFK 

and chlorophyll a concentrations, yet be placed in 

different trophic states.

Nitrogen occurs in natural waters in several 

different forms—dissolved molecular nitrogen (N2), 

organic compounds (amino acids, amines, proteins, 

and refractory humic compounds of low nitrogen 

content), ammonia (NH4

+), nitrite (NO2-

), and nitrate 

(NO3

+). Total Kjeldahl nitrogen (TKN) is the sum of 

total organic nitrogen and total ammonia species. For 

this report, total inorganic nitrogen (TIN) is the sum of 

total nitrate and nitrite species. 

Nitrogen from specific sources enters the 

hydrologic cycle in characteristic forms. Sources of 

TKN include the decay of organic material, such as 

vegetation (algae), animal wastes, and urban sewage. 

Large amounts of ammonia and organic nitrogen are 

applied to cropland as fertilizers, but are relatively 

immobile in soils because of adsorption to soil 

surfaces. Under oxygen-rich conditions, however, TKN 

can be converted to the extremely mobile forms of 

nitrate and nitrite, which readily enter the ground- and 

surface-water systems. 

A biologically catalyzed cycle converts one form 

of nitrogen into another. Bacteria and blue-green algae 

can transform atmospheric nitrogen into ammonia by 

the process called nitrogen fixation. Other bacteria 

catalyze the oxidation of ammonium to nitrite, then to 

nitrate by the process called nitrification; this process 

occurs rapidly in the oxygen-rich environment of most 

streams. Ammonia is the preferred form for algal 

uptake, followed by nitrate and nitrite, then dissolved 

molecular nitrogen (Wetzel, 1983). These nitrogen 

species can be taken up by organisms and incorporated 

into organic materials, which in turn decay and release 

nitrogen in the form of ammonia. 

Like nitrogen, phosphorus exists in the aquatic 

environment in several forms, including inorganic and 

organic species. The most important form of inorganic 

phosphorus is orthophosphate (PO4

-3) which is the 

form of phosphorus that is available for use by biota 

(Wetzel, 1983). Approximately 30 to 60 percent of the 

phosphorus in many natural waters is organically 

bound (Snoeyink and Jenkins, 1980). Phosphorus tends 

to adsorb strongly to particles in soils, suspended 

solids, and bed sediments.

Potential sources of nutrients in the Converse 

Lake watershed are from nonpoint contributions from 

atmospheric deposition, fertilizer applications on 

agricultural and residential land, livestock wastes, 

residential runoff, failing septic systems, contaminated 

ground water, and natural sources. No known point 

sources are located in the Converse Lake watershed. 

1XWULHQW$QDO\VLV0HWKRGVDQG$SSURDFK

Trends in concentrations of total nitrogen and 

phosphorus, total inorganic nitrogen, total Kjeldahl 

nitrogen, and total orthophosphate (as phosphorus) 

were determined for one lake and seven tributary sites 

from water-quality data collected during the period 

October 1990 to June 1998. Trend analyses were 

performed on actual concentrations and concentrations 

adjusted for streamflow by using a statistical technique 

known as Locally Weighted Regression and Smoothing 

of Scatter Plots (LOWESS). This technique produces a 

continuous curvilinear line through the data points. 

Flow adjustment of concentration data eliminates 

variations in concentrations related to streamflow, 

allowing for a more accurate detection of trends in 

water quality over time. The actual concentrations and 

the residuals from the LOWESS relation were 

subjected to a trend analysis known as a seasonal 

Kendall trends test (Hirsch and others, 1982; Helsel 

and Hirsch, 1992), which accounts for seasonal 

variations in the constituent concentrations.

Annual and monthly in-stream loads of nitrogen, 

phosphorus, and silica were calculated as the product 

of the daily streamflow and estimated daily 

concentrations for the three continuous-record surfacewater stations (Big Creek, Crooked Creek, and 

Hamilton Creek). Daily constituent concentration data 

were estimated by using Cohn’s estimator model (Cohn 

and others, 1989; Gilroy and others, 1990; Cohn and 

others, 1992). This model includes a seven-constituent 

log-linear regression analysis of constituent 

concentrations against measured environmental 

variables.

(1)

where

ln = natural logarithm function,

C = concentration (in milligrams per liter),

Q = instantaneous discharge (in cubic feet per 

second),

t = time (in decimal years),

ln( ) C β0 β1 〈 〉β ln[ ] Q Q– ′ 2( ) ln[ ] Q Q– ′ 2

β3[ ]β t t – ′ 4 + [ ] t t – ′ 2 β5 sin[ ] 2πt

β6 cos[ ] 2πt ε ,

+

+ +

+ +

+

=
 $VVHVVPHQWRI:DWHU4XDOLW\&RQGLWLRQVLQWKH-%&RQYHUVH/DNH:DWHUVKHG0RELOH&RXQW\$ODEDPD¥

sin = sine function,

cos = cosine function,

π = 3.14169,

β0 to β6 = coefficients of the regression model,

ε = model errors,

= centering variable defined so that β1 and β2

are statistically independent, and

= centering variable defined so that β3 and β4

are statistically independent.

The regression analysis assumes that model 

errors (ε) are independent and normally distributed, 

with zero mean and variance. The Minimum Variance 

Unbiased Estimator (MVUE) (Bradu and Mundlak, 

1970) was included in the model to correct for the 

retransformation bias associated with log-linear 

regression models; the model also employs the 

Adjusted Maximum Likelihood Estimator (Cohn, 

1988), which statistically adjusts for censored data and 

multiple reporting limits. 

Equation 1 results in an estimate of the daily 

logarithmic constituent concentrations. The estimated 

daily constituent concentrations are then multiplied by 

the daily mean discharge to produce a daily mean load 

by using the following equation.

, (2)

where

ln = the natural logarithm function,

Li

 = the daily mean load (in kilograms per day),

i = any interval,

Qi = the daily mean discharge for that interval 

(in cubic feet per second),

Ci = the mean concentration (in milligrams per 

liter), and

K = 2.447, the correction factor for unit 

conversion.

Yields allow easy comparison among sites with differing drainage areas; yields were computed by dividing 

the estimated load by the drainage area of the subbasin.

5HVXOWVRI1XWULHQW$QDO\VLV

Annual and monthly nutrient loads were 

estimated at three tributary sites in the Converse Lake 

watershed by using regression techniques. Nutrient 

yields also were computed from the estimated loads to 

allow for comparison among sites. Nutrient 

concentrations from October 1990 to June 1998 were 

analyzed to determine if any trends existed at the seven 

tributary sites and one lake site (site LHAM). The 

trophic response of the lake to the nutrient loads also 

was evaluated. 

1XWULHQW/RDGV

Regression analyses were performed on seven 

species of nutrients—total inorganic nitrogen, 

ammonia, organic nitrogen, total Kjeldahl nitrogen, 

total nitrogen, total phosphorus, and orthophosphate. 

Regression summaries for the input data of nutrient 

concentrations are listed in table 9. Data used as input 

to the logarithmic-linear regression model are 

statistically summarized in appendix 1. Regression 

summaries include the variance (s) and the coefficient 

of determination (r2

) for each constituent, the model 

variables, and the coefficients used to determine the 

concentration for each variable. 

The T value is the measure of the significance of 

the coefficients in the seven-parameter model. A model 

value with an absolute T value greater than 2 is 

considered to be significant, with the exception of the 

sine and cosine variables (β5 and β6, respectively). 

Because these variables together indicate seasonality, if 

either variable is significant, the other is considered 

significant. A significant variable indicates a relation to 

constituent concentration. For example, the statistical 

significance of variable β1 indicates that streamflow, 

independent of other influences, is a good predictor of 

concentration. Temporal trends in nutrient 

concentrations are interpreted based on the statistical 

significance of β3. Significant coefficients based on 

T values (not listed) are shown in bold in table 9.

The r2, or coefficient of determination, is the 

percentage of the variation explained by the regression 

equation. For example, an r2

 of 74 indicates that 

approximately 74 percent of the variation in the actual 

data is explained by the equation. Because the data sets 

used to develop these equations cover only 1 year for 

Long and Boggy Branch and 2 years for Juniper and 

Collins Creek, the equations have relatively higher 

variance, as represented by the s values. Errors 

associated with predicted concentrations decrease as 

the number of samples collected increases.

The relative influence of nonpoint sources and 

point sources on water quality in the selected tributary 

subbasins can be examined by comparing the statistical 

significance of the streamflow regression coefficient, 

Q′

t′

Li ln[ ] Qi Ci = × ln[ ] × K
5HVXOWVRI1XWULHQW$QDO\VLV 

7DEOH 5HJUHVVLRQVXPPDU\IRUWKHVHYHQSDUDPHWHUORJOLQHDUPRGHOXVHGWRHVWLPDWHQXWULHQWFRQFHQWUDWLRQVDWVHOHFWHGVLWHVLQ

WKH&RQYHUVH/DNHZDWHUVKHG

[s, standard deviation of the residuals from ordinary least squares fit; r2, coefficient of determination; n, number of observations used to fit the model; 

β0, constant; β1, coefficient of natural logarithm of streamflow; β2, coefficient of natural logarithm of streamflow, squared; β3, coefficient of time; 

β4, coefficient of time, squared; β5, coefficient of sine (time); β6, coefficient of cosine (time); bold indicates coefficients with an absolute T value 

greater than 2, which indicates significance; —, no data] 

Big Creek at County Road 63 near Wilmer, 02479945 (site BIG)

V U Q β β β β β β β

Total nitrogen

0.17462 0.952 36 4.5788 0.9617 0.0654 -0.0381 0.0128 -0.1205 -0.0886

Total Kjeldahl nitrogen

0.25928 0.944 45 3.8143 1.3822 0.0548 -0.0789 -0.0059 -0.1280 -0.2428

7RWDORUJDQLFQLWURJHQ

0.45647 0.619 45 1.3867 0.5916 -0.2125 -0.0826 -0.0036 0.1227 -0.0300

7RWDODPPRQLDQLWURJHQ

0.23379 0.954 35 3.8086 1.4066 0.0416 -0.0087 0.0132 -0.2075 -0.2683

7RWDOLQRUJDQLFQLWURJHQ

0.65873 0.370 46 3.4199 0.3984 0.0886 -0.1155 0.0256 0.0654 0.0854

7RWDOSKRVSKRUXV

0.79814 0.564 47 0.8598 1.2094 — 0.0384 — -0.1885 0.0852

7RWDORUWKRSKRVSKRUXV

0.00000 1.000 46 0.3698 1.0000 — 0.0000 — 0.0000 0.0000

Juniper Creek at Glenwood Road near Fairview, 02479948 (site JUN)

V U Q β β β β β β β

7RWDOQLWURJHQ

0.21120 0.914 15 3.6186 1.2182 -0.2516 0.1828 0.3444 -0.0197 -0.0604

7RWDO.MHOGDKOQLWURJHQ

0.48771 0.780 22 2.5123 1.9145 -0.3111 0.0472 0.5640 -0.0030 -0.1662

7RWDORUJDQLFQLWURJHQ

0.50111 0.736 21 -0.2969 1.8449 -0.3239 0.2984 0.4448 -0.1841 0.2092

7RWDODPPRQLDQLWURJHQ

0.35746 0.902 14 2.6389 1.7567 -0.9557 0.0969 1.7190 -0.2388 -0.1634

7RWDOLQRUJDQLFQLWURJHQ

0.14268 0.865 22 2.9863 0.5089 -0.0527 0.1211 -0.3242 0.0556 0.0087

7RWDOSKRVSKRUXV

1.6806 0.559 22 -0.0208 3.0008 — 1.1154 — -0.5257 0.5632

7RWDORUWKRSKRVSKRUXV

— —— — — — — — — —

Collins Creek at Glenwood Road near Fairview, 02479950 (site COL)

V U Q β β β β β β β

7RWDOQLWURJHQ

0.18147 0.947 15 3.0989 1.2212 0.2776 -0.0434 -0.1851 -0.0271 -0.0545

7RWDO.MHOGDKOQLWURJHQ

0.27668 0.889 22 2.5112 1.5333 0.4112 -0.0011 -0.1261 -0.0030 -0.1979

7RWDORUJDQLFQLWURJHQ

0.35532 0.842 22 -0.1938 1.8439 -0.7371 0.2604 0.3858 -0.2329 -0.3952

7RWDODPPRQLDQLWURJHQ

0.22210 0.945 15 2.5664 1.3756 0.5555 -0.0960 -0.2207 0.0444 -0.1052

7RWDOLQRUJDQLFQLWURJHQ

0.17477 0.839 23 1.9871 0.8225 -0.3740 0.0536 -0.1092 -0.0998 0.0874

7RWDOSKRVSKRUXV

0.69307 0.504 24 -0.3192 1.5228 0.3541 0.4934 -0.0690 0.0052 0.2477

7RWDORUWKRSKRVSKRUXV

— —— — — — — — — —
 $VVHVVPHQWRI:DWHU4XDOLW\&RQGLWLRQVLQWKH-%&RQYHUVH/DNH:DWHUVKHG0RELOH&RXQW\$ODEDPD¥

Long Branch near Wilmer, 02479955 (site LON)

V U Q β β β β β β β

7RWDOQLWURJHQ

0.32975 0.915 10 4.0791 1.1099 -0.0016 0.8848 -16.9089 -1.4540 0.2904

7RWDO.MHOGDKOQLWURJHQ

0.61057 0.694 12 1.5759 1.5055 — 0.8309 — -0.2587 -0.1209

7RWDORUJDQLFQLWURJHQ

0.51128 0.715 11 -0.3187 1.7021 — 1.0415 — -0.3502 0.5939

7RWDODPPRQLDQLWURJHQ

0.64878 0.583 10 1.6432 1.2254 — -0.0024 — -0.1950 -0.4100

7RWDOLQRUJDQLFQLWURJHQ

0.20918 0.948 12 2.1060 1.4223 — 0.2951 — 0.1310 0.2797

7RWDOSKRVSKRUXV

0.87464 0.303 12 -1.6383 0.7019 — 1.2450 — -0.2464 0.1349

7RWDORUWKRSKRVSKRUXV

— —— — — — — — — —

Boggy Branch near Wilmer, 02479960 (site BOG)

V U Q β β β β β β β

7RWDOQLWURJHQ

0.33084 0.949 12 1.4754 1.2912 0.3733 -0.0992 -1.3389 -0.2691 -0.2252

7RWDO.MHOGDKOQLWURJHQ

0.38391 0.912 12 1.2347 1.3736 — -1.1838 — -0.1122 -0.6940

7RWDORUJDQLFQLWURJHQ

0.58766 0.720 11 -1.7646 0.8351 — 1.0541 — 0.0528 -0.1367

7RWDODPPRQLDQLWURJHQ

0.41959 0.929 11 1.9234 1.1463 0.7731 0.0081 -11.8689 -1.0106 -0.1948

7RWDOLQRUJDQLFQLWURJHQ

0.30845 0.921 12 0.1871 1.3184 — 0.3513 — -0.3106 0.2623

7RWDOSKRVSKRUXV

0.35835 0.461 12 -1.6876 0.2324 — 0.4350 — 0.0446 0.0386

7RWDORUWKRSKRVSKRUXV

— —— — — — — — — —

Crooked Creek near Fairview, 02479980 (site CRO)

V U Q β β β β β β β

7RWDOQLWURJHQ

0.27019 0.831 33 3.6626 1.2274 -0.0626 -0.0019 -0.0078 -0.1549 -0.0960

7RWDO.MHOGDKOQLWURJHQ

0.49310 0.697 48 2.5244 1.5384 0.0311 -0.0803 -0.0009 -0.0303 -0.3407

7RWDORUJDQLFQLWURJHQ

0.46168 0.715 47 0.0032 1.4031 -0.0448 0.0501 -0.0225 0.2067 -0.1162

7RWDODPPRQLDQLWURJHQ

0.44554 0.753 31 2.9074 1.5571 -0.0208 -0.0181 -0.0033 -0.2773 -0.2374

7RWDOLQRUJDQLFQLWURJHQ

0.47087 0.374 48 2.4798 0.7253 0.0558 -0.0406 0.0168 0.0326 -0.0527

7RWDOSKRVSKRUXV

0.71127 0.560 48 0.0566 1.7386 — -0.0052 — 0.1320 0.0004

7RWDORUWKRSKRVSKRUXV

0.37663 0.683 45 -0.7975 1.2952 — -0.0546 — -0.0929 0.0463

7DEOH 5HJUHVVLRQVXPPDU\IRUWKHVHYHQSDUDPHWHUORJOLQHDUPRGHOXVHGWRHVWLPDWHQXWULHQWFRQFHQWUDWLRQVDWVHOHFWHGVLWHVLQ

WKH&RQYHUVH/DNHZDWHUVKHG¦&RQWLQXHG

[s, standard deviation of the residuals from ordinary least squares fit; r2, coefficient of determination; n, number of observations used to fit the model; 

β0, constant; β1, coefficient of natural logarithm of streamflow; β2, coefficient of natural logarithm of streamflow, squared; β3, coefficient of time; 

β4, coefficient of time, squared; β5, coefficient of sine (time); β6, coefficient of cosine (time); bold indicates coefficients with an absolute T value 

greater than 2, which indicates significance; —, no data] 
5HVXOWVRI1XWULHQW$QDO\VLV 

Hamilton Creek at Snow Road near Semmes, 02480002 (site HAM)

V U Q β β β β β β β

7RWDOQLWURJHQ

0.12143 0.930 28 4.0483 0.8320 0.0846 -0.0389 -0.0025 -0.0174 -0.0070

7RWDO.MHOGDKOQLWURJHQ

0.34478 0.789 47 3.0790 1.5212 -0.0292 -0.0974 -0.0051 -0.0541 -0.1981

7RWDORUJDQLFQLWURJHQ

0.44160 0.706 46 1.0568 1.5513 -0.4915 0.0022 -0.0314 0.0870 -0.0826

7RWDODPPRQLDQLWURJHQ

0.30069 0.849 28 3.2374 1.3453 0.0341 -0.0828 -0.0018 -0.0766 -0.0766

7RWDOLQRUJDQLFQLWURJHQ

0.09986 0.723 47 3.3101 0.2486 -0.2291 -0.0030 0.0021 0.0308 0.0992

7RWDOSKRVSKRUXV

0.77744 0.456 47 0.5527 1.6829 — -0.0443 — -0.0346 -0.2391

7RWDORUWKRSKRVSKRUXV

0.24929 0.788 45 -0.3123 1.0960 — -0.0172 — 0.0790 -0.0700

7DEOH 5HJUHVVLRQVXPPDU\IRUWKHVHYHQSDUDPHWHUORJOLQHDUPRGHOXVHGWRHVWLPDWHQXWULHQWFRQFHQWUDWLRQVDWVHOHFWHGVLWHVLQ

WKH&RQYHUVH/DNHZDWHUVKHG¦&RQWLQXHG

[s, standard deviation of the residuals from ordinary least squares fit; r2, coefficient of determination; n, number of observations used to fit the model; 

β0, constant; β1, coefficient of natural logarithm of streamflow; β2, coefficient of natural logarithm of streamflow, squared; β3, coefficient of time; 

β4, coefficient of time, squared; β5, coefficient of sine (time); β6, coefficient of cosine (time); bold indicates coefficients with an absolute T value 

greater than 2, which indicates significance; —, no data] 

β1 (table 9). A significant, positive relation between 

streamflow and nutrient concentration indicates that 

nonpoint sources are the dominant source of input. If 

the relation is significantly negative, the primary source 

of nutrients is point sources. Total nitrogen (except at 

site LON), total Kjeldahl nitrogen (except at 

site HAM), total organic nitrogen (except at site BOG), 

ammonia (except at site LON), total inorganic nitrogen, 

and total phosphorus (except at sites LON and BOG) 

exhibited a significant, positive relation with 

streamflow, indicating that the dominant source of 

nutrient input to the watershed is from nonpoint 

sources. 

The seasonal variation of nutrient concentrations 

has been attributed to several natural and cultural 

factors, including seasonal changes in algal or aquatic 

macrophyte uptake, fertilizer applications, or 

temperature-driven nitrification processes. A 

significant seasonal pattern, independent of flow 

variation, was observed for total nitrogen, total Kjeldahl 

nitrogen, and ammonia at sites BIG and CRO; for total 

Kjeldahl nitrogen and total organic nitrogen at 

site COL; and for total Kjeldahl and inorganic nitrogen 

at site HAM. 

Different land-use practices contribute different 

levels of nutrients by nonpoint sources. A study by 

Reckhow and others (1980) summarized literature 

values of nutrient export from a variety of nonpoint 

sources (table 10). The range in nutrient yields is due to 

differences in climate, soils, and land-management 

practices for each category. 

Annual yields at all monitored sites in the 

Converse Lake watershed were computed for total 

phosphorus, total inorganic nitrogen, total Kjeldahl 

nitrogen, and total nitrogen for the 1991 water year 

when all sites had continuous streamflow record 

(table 11). The total phosphorus yields ranged from 

0.10 (site LON) to 0.52 (site CRO) (kg/ha)/yr, and total 

nitrogen yields ranged from 3.83 (site COL) to 8.45 

(site BIG) (kg/ha)/yr (table 11). When compared to 

table 10, the computed total phosphorus yields for Big 

Creek, Collins Creek, Long Branch, and Boggy Branch 

are within the expected range for forested land with 

minor agriculture (pasture, crops, mixed agriculture). 

Crooked Creek (site CRO) and Hamilton Creek 

(site HAM) subbasins had higher residential and 

nonrow crop (plant nurseries) land use (table 4) and 

higher total phosphorus yields (0.52 and 

0.40 [kg/ha]/yr, respectively) than the other tributary 

subbasins. Juniper Creek (site JUN) subbasin had a 

total phosphorus yield of 0.45 (kg/ha)/yr, which was 

within the range observed at Crooked and Hamilton 

Creek; however, little to no residential influence is 

present in Juniper Creek (table 4). The total nitrogen 
 $VVHVVPHQWRI:DWHU4XDOLW\&RQGLWLRQVLQWKH-%&RQYHUVH/DNH:DWHUVKHG0RELOH&RXQW\$ODEDPD¥

7DEOH 5DQJHLQQXWULHQW\LHOGVIURPQRQSRLQWVRXUFHVPRGLILHGIURP5HFNKRZDQGRWKHUV

'RPLQDQW

ODQGXVH

1XWULHQW\LHOGVLQNLORJUDPVSHUKHFWDUHSHU\HDU

0HDQ 0LQLPXP 0HGLDQ 0D[LPXP

7RWDOSKRVSKRUXVH[SRUW

Forest 0.24 0.02 0.21 0.83

Row crops 4.46 0.26 2.24 18.6

Nonrow crops 1.08 0.10 0.76 2.90

Pasture 1.50 0.14 0.81 4.90

Feedlots 301 21.3 224 795

Mixed agriculture 1.13 0.08 0.91 3.25

Urban 1.91 0.19 1.10 6.23

7RWDOQLWURJHQH[SRUW

Forest 2.86 1.38 2.46 6.26

Row crops 16.1 2.10 9.00 79.6

Nonrow crops 5.19 0.97 6.08 7.82

Pasture 8.65 1.48 5.19 30.9

Feedlot 3,110 681 2,920 7,980

Mixed agriculture 16.5 2.82 14.3 41.5

Urban 9.97 1.48 5.50 38.5

7DEOH $QQXDOQXWULHQWORDGVDQG\LHOGVIRUVHOHFWHGWULEXWDU\VLWHVLQWKH&RQYHUVH/DNHZDWHUVKHGIRUZDWHU\HDU

[—, no data]

6LWH

ODEHO

ILJ

6WDWLRQ

QDPH

$QQXDOQXWULHQWORDGV

LQNLORJUDPV

$QQXDOQXWULHQW\LHOGV

LQNLORJUDPVSHUKHFWDUHSHU\HDU

7RWDO

SKRVSKRUXV

7RWDO

LQRUJDQLF

QLWURJHQ

7RWDO

.MHOGDKO

QLWURJHQ

7RWDO

QLWURJHQ

7RWDO

SKRVSKRUXV

7RWDO

LQRUJDQLF

QLWURJHQ

7RWDO

.MHOGDKO

QLWURJHQ

7RWDO

QLWURJHQ

BIG Big Creek 1,880 27,300 58,800 69,000 0.23 3.35 7.19 8.45

JUN Juniper Creek 1,080 6,360 6,390 2,410 0.45 2.66 2.68 5.59

COL Collins Creek 270 2,260 6,360 8,510 0.12 1.02 2.88 3.83

LON Long Branch 87.7 4,640 2,710 5,440 0.10 5.62 3.30 6.61

BOG Boggy Branch 76.7 1,580 5,520 — 0.11 2.14 7.45 —

CRO Crooked Creek 1,080 6,900 10,800 15,200 0.52 3.29 5.16 7.24

HAM Hamilton Creek 847 8,620 8,840 17,400 0.40 4.04 4.14 8.16

TOTAL 5,245 57,660 99,420 118,000 — — — —

yields at the tributary sites fell within the published 

range of forested, agricultural (pasture, nonrow crops), 

and urban land use.

The total annual nutrient loads to Converse Lake 

for the 1991 water year were 5,245 kg for total 

phosphorus, 57,660 kg for total inorganic nitrogen, 

99,420 kg for total Kjeldahl nitrogen, and 118,000 kg 

for total nitrogen (table 11). The nutrient loads at Big 

Creek, Crooked Creek, and Hamilton Creek accounted 

for over 70 percent of the total load in the watershed. 

Big Creek had the highest nutrient loads, accounting for 

almost 60 percent of the total nitrogen and total 

Kjeldahl nitrogen, 47 percent of the total inorganic 

nitrogen, and 36 percent of total phosphorus loads. 

Crooked and Juniper Creeks each contributed 

21 percent of the total phosphorus load in 1991, and 

Hamilton Creek contributed about 16 percent. Total 

phosphorus yields from the Crooked, Juniper, and 

Hamilton Creek subbasins are 2 to 5 times those of the 

other tributary subbasins.

Annual loads were computed for the 1991 to 

1998 water years at the three gaged sites—Big Creek 

(table 12), Crooked Creek (table 13), and Hamilton 

Creek (table 14). During the study period, nutrient 

loads and yields at all three sites were highest in the 

1991 and 1998 water years; nutrient loads and yields 

were lowest in the 1992 and 1994 water years, except 

for total inorganic nitrogen in 1995. The mean annual 

loads and yields represent the average annual 

contribution of nutrients to Converse Lake for the study 
5HVXOWVRI1XWULHQW$QDO\VLV 

7DEOH $QQXDODQGPHDQDQQXDOQXWULHQWORDGVDQG\LHOGVIRU%LJ&UHHNVLWH%,*&RQYHUVH/DNH

ZDWHUVKHGZDWHU\HDUV¥

[kg/d, kilogram per day; g/d, gram per day; (kg/ha)/yr, kilogram per hectare per year]

$QQXDOORDGV

:DWHU\HDU 2UWKRSKRVSKDWH

NJG

7RWDO

SKRVSKRUXV

NJG

7RWDO

LQRUJDQLF

QLWURJHQ

NJG

7RWDO

DPPRQLD

JG

7RWDO

.MHOGDKO

QLWURJHQ

NJG

7RWDO

QLWURJHQ

NJG

1991 840 1,880 27,300 49.7 58,700 69,000

1992 472 1,050 18,000 16.7 19,700 33,800

1993 748 1,850 17,400 34.3 39,200 51,500

1994 442 1,020 12,400 15.5 16,300 29,100

1995 550 1,340 12,000 23.6 22,900 36,000

1996 747 2,060 13,100 34.6 29,800 49,200

1997 543 1,380 12,000 23.6 16,200 37,000

1998 816 2,530 13,400 64.5 35,800 66,300

Mean annual 645 1,640 15,700 32.8 29,800 46,500

$QQXDO\LHOGV>NJKD@\U

:DWHU\HDU 2UWKRSKRVSKDWH 7RWDO

SKRVSKRUXV

7RWDO

LQRUJDQLF

QLWURJHQ

7RWDO

DPPRQLD

7RWDO

.MHOGDKO

QLWURJHQ

7RWDO

QLWURJHQ

1991 0.103 0.230 3.35 0.0061 7.19 8.45

1992 0.058 0.129 2.20 0.0020 2.42 4.15

1993 0.092 0.226 2.13 0.0042 4.81 6.31

1994 0.054 0.125 1.52 0.0019 2.00 3.56

1995 0.067 0.164 1.48 0.0029 2.80 4.41

1996 0.092 0.252 1.60 0.0042 3.65 6.03

1997 0.067 0.169 1.48 0.0029 1.99 4.52

1998 0.100 0.311 1.64 0.0079 4.38 8.13

Mean annual 0.079 0.201 1.93 0.0040 3.66 5.70

7DEOH $QQXDODQGPHDQDQQXDOQXWULHQWORDGVDQG\LHOGVIRU&URRNHG&UHHNVLWH&52&RQYHUVH/DNH

ZDWHUVKHGZDWHU\HDUV¥

[kg/d, kilogram per day; g/d, gram per day; (kg/ha)/yr, kilogram per hectare per year]

$QQXDOORDGV

:DWHU\HDU 2UWKRSKRVSKDWH

NJG

7RWDO

SKRVSKRUXV

NJG

7RWDO

LQRUJDQLF

QLWURJHQ

NJG

7RWDO

DPPRQLD

JG

7RWDO

.MHOGDKO

QLWURJHQ

NJG

7RWDO

QLWURJHQ

NJG

1991 283 1,080 6,890 9.49 10,800 15,200

1992 154 480 4,620 4.93 4,820 9,580

1993 210 850 4,860 7.12 6,630 13,300

1994 115 366 3,600 4.62 3,970 8,800

1995 173 913 3,970 6.34 5,420 11,600

1996 212 1,030 4,570 7.79 5,820 14,200

1997 215 1,130 5,150 10.5 7,890 16,300

1998 306 1,890 5,880 10.0 6,690 17,570

Mean annual 208 967 4,940 7.59 6,510 13,300

$QQXDO\LHOGV>NJKD@\U

:DWHU\HDU 2UWKRSKRVSKDWH 7RWDO

SKRVSKRUXV

7RWDO

LQRUJDQLF

QLWURJHQ

7RWDO

DPPRQLD

7RWDO

.MHOGDKO

QLWURJHQ

7RWDO

QLWURJHQ

1991 0.135 0.517 3.29 0.0045 5.16 7.24

1992 0.0733 0.229 2.21 0.0024 2.30 4.58

1993 0.100 0.406 2.32 0.0034 3.17 6.34

1994 0.0549 0.179 1.72 0.0022 1.90 4.21

1995 0.0826 0.436 1.89 0.0030 2.59 5.54

1996 0.101 0.492 2.18 0.0037 2.78 6.80

1997 0.103 0.540 2.46 0.0050 3.77 7.79

1998 0.146 0.903 2.81 0.0048 3.19 8.40

Mean annual 0.100 0.462 2.36 0.0036 3.11 6.36
 $VVHVVPHQWRI:DWHU4XDOLW\&RQGLWLRQVLQWKH-%&RQYHUVH/DNH:DWHUVKHG0RELOH&RXQW\$ODEDPD¥

7DEOH $QQXDODQGPHDQDQQXDOQXWULHQWORDGVDQG\LHOGVIRU+DPLOWRQ&UHHNVLWH+$0&RQYHUVH/DNH

ZDWHUVKHGZDWHU\HDUV¥

[kg/d, kilogram per day; g/d, gram per day; (kg/ha)/yr, kilogram per hectare per year]

$QQXDOORDGV

:DWHU\HDU 2UWKRSKRVSKDWH

NJG

7RWDO

SKRVSKRUXV

NJG

7RWDO

LQRUJDQLF

QLWURJHQ

NJG

7RWDO

DPPRQLD

JG

7RWDO

.MHOGDKO

QLWURJHQ

NJG

7RWDO

QLWURJHQ

NJG

1991 225 857 8,610 8.41 8,820 17,400

1992 171 469 8,120 5.44 5,300 14,100

1993 196 686 8,080 6.22 6,230 15,300

1994 142 405 7,470 4.08 3,990 12,150

1995 191 795 7,700 5.51 5,630 14,300

1996 237 960 8,450 6.56 6,350 16,300

1997 211 901 8,400 5.64 5,720 14,700

1998 342 1,950 9,010 6.93 6,340 20,300

Mean annual 214 876 8,230 6.09 6,050 15,600

$QQXDO\LHOGV>NJKD@\U

:DWHU\HDU 2UWKRSKRVSKDWH 7RWDO

SKRVSKRUXV

7RWDO

LQRUJDQLF

QLWURJHQ

7RWDO

DPPRQLD

7RWDO

.MHOGDKO

QLWURJHQ

7RWDO

QLWURJHQ

1991 0.106 0.398 4.04 0.0039 4.14 8.16

1992 0.0801 0.221 3.81 0.0026 2.49 6.64

1993 0.0920 0.322 3.79 0.0029 2.93 7.17

1994 0.0667 0.190 3.51 0.0019 1.87 5.71

1995 0.0896 0.374 3.62 0.0026 2.64 6.73

1996 0.111 0.451 3.97 0.0030 2.98 7.67

1997 0.0993 0.423 3.95 0.0027 2.69 6.91

1998 0.161 0.914 4.23 0.0033 2.98 9.54

Mean annual 0.101 0.412 3.87 0.0029 2.84 7.32

period. A combined mean annual load of 75,400 kg of 

total nitrogen, 36,950 kg of total Kjeldahl nitrogen, 

28,870 kg of total inorganic nitrogen, and 3,480 kg of 

total phosphorus was contributed to the lake by these 

sites during the 1991 to 1998 water years. Of the 

combined loads, 62 percent of the total nitrogen, 

70 percent of the total Kjeldahl nitrogen, 54 percent of 

the total inorganic nitrogen, and 47 percent of the total 

phosphorus originated from the forested subbasin of 

Big Creek. The more residential and agricultural 

subbasins of Crooked Creek and Hamilton Creek, 

however, yielded over twice the total phosphorus per 

hectare of land use (fig. 17). Crooked and Hamilton 

Creek subbasins also had higher total inorganic 

nitrogen yields. The mean annual nutrient yields for the 

three sites were averaged to obtain a watershed yield for 

each nutrient species—0.0933 (kg/ha)/yr for 

orthophosphate, 0.358 (kg/ha)/yr for total phosphorus, 

2.72 (kg/ha)/yr for total inorganic nitrogen, 

0.0035 (kg/ha)/yr for total ammonia, 3.20 (kg/ha)/yr for 

total Kjeldahl nitrogen, and 6.46 (kg/ha)/yr for total 

7DEOH (VWLPDWHGPHDQDQQXDOQXWULHQWFRQWULEXWLRQVWR

&RQYHUVH/DNH

[(kg/ha)/yr, kilogram per hectare per year; kg/yr, kilogram per year]

1XWULHQW

1XWULHQWFRQWULEXWLRQV

WRWKHZDWHUVKHG

<LHOGD

>NJKD@\U

a

Estimated by averaging the mean annual yields of the selected 

nutrients listed in tables 12, 13, and 14.

/RDGE

NJ\U

b

Estimated by multiplying yield by 26,677 hectares (drainage area of 

watershed).

Orthophosphate 0.0933 2,490

Total phosphorus 0.358 9,550

Total inorganic nitrogen 2.72 72,600

Total ammonia 0.0035 93

Total Kjeldahl nitrogen 3.20 85,400

Total nitrogen 6.46 172,000

nitrogen (fig. 17). The 103-mi2 drainage area of the 

Converse Lake watershed is equivalent to 

26,677 hectares. These estimated values were used to 

compute a mean annual nutrient contribution to 

Converse Lake (table 15). 
5HVXOWVRI1XWULHQW$QDO\VLV 

)LJXUH 0HDQDQQXDOQXWULHQW\LHOGVIRUWKUHHVLWHVLQWKH&RQYHUVH/DNHZDWHUVKHG¥
 $VVHVVPHQWRI:DWHU4XDOLW\&RQGLWLRQVLQWKH-%&RQYHUVH/DNH:DWHUVKHG0RELOH&RXQW\$ODEDPD¥

(LJKW<HDU7UHQG$QDO\VLV

Statistical significance levels were determined 

for each variable by the Kendall tau trend test, which 

accounts for seasonal variations in the constituent 

concentrations. The unadjusted trends were computed 

by using actual concentrations, and the adjusted trends 

were computed by using the residuals from the 

LOWESS relation (table 16). A two-sided probability 

or p-value was used to describe the attained 

significance level. Trend analysis was considered 

significant at a 95-percent confidence level when the 

trend test detected an actual or real trend and the 

estimate had a p-value less than 0.05. 

The trend analysis indicated little or no change in 

nutrient concentrations at the tributary and lake sites in 

the Converse Lake watershed from 1990 to 1998. 

Minimal decreases in total organic nitrogen were 

observed for Juniper Creek (0.005 [mg/L]/yr—

unadjusted), Crooked Creek (0.007 [mg/L]/yr), and 

Hamilton Creek (0.003 [mg/L]/yr). Collins Creek and 

Hamilton Creek also had small, but significant, 

decreases in total Kjeldahl nitrogen (0.011 and 

0.005 [mg/L]/yr, respectively). The only significant 

increase in nutrient concentrations was for total 

phosphorus at Long Branch, which was less than 

0.001 (mg/L)/yr. 

7DEOH 5HVXOWVRIWKHVHDVRQDO.HQGDOOWDXWHVWIRUWUHQGVLQXQDGMXVWHGDQGIORZDGMXVWHGQXWULHQWFRQFHQWUDWLRQVDWVHOHFWHGVLWHVLQ

WKH&RQYHUVH/DNHZDWHUVKHG¥

[Trends reported in units of milligrams per liter per year; bold values represent significant trends with p-value less than or equal to 0.05; <, less than; 

—, not applicable]

&RQVWLWXHQW 8QDGMXVWHG $GMXVWHG

7UHQG WDXYDOXH SYDOXH 7UHQG WDXYDOXH SYDOXH

%,*&5((.6,7(%,*

Total inorganic nitrogen 0.010 0.22 0.180 -0.004 -0.13 0.431

Dissolved inorganic nitrogen 0.010 0.24 0.158 -0.002 -0.09 0.603

Total ammonia 0 -0.15 0.358 -0.001 -0.16 0.347

Total organic nitrogen -0.007 -0.19 0.363 -0.003 -0.05 0.856

Total nitrogen -0.005 -0.10 0.692 -0.038 -0.15 0.497

Total Kjeldahl nitrogen -0.009 -0.13 0.530 -0.008 -0.21 0.287

Total phosphorus 0 0.22 0.303 0.0011 0.28 0.240

-81,3(5&5((.6,7(-81

Total inorganic nitrogen 0.006 0.13 0.506 -0.001 -0.03 0.933

Dissolved inorganic nitrogen 0.005 0.13 0.506 0.002 0.04 0.868

Total ammonia 0 0.18 0.278 0.0001 0.03 0.933

Total organic nitrogen -0.005 -0.39 0.022 -0.004 -0.17 0.362

Total nitrogen -0.004 -0.11 0.559 0.004 0.14 0.455

Total Kjeldahl nitrogen 0 -0.25 0.113 -0.004 -0.21 0.244

Total phosphorus 0 0.29 0.052 0.00004 0.28 0.107

&2//,16&5((.6,7(&2/

Total inorganic nitrogen 0.005 0.24 0.180 0.005 0.19 0.278

Dissolved inorganic nitrogen 0.005 0.31 0.079 0.006 0.25 0.156

Total ammonia 0 -0.03 0.925 0 0 1.000

Total organic nitrogen 0.001 0.04 1.000 -0.030 -0.42 0.151

Total nitrogen -0.023 -0.16 0.704 -0.015 -0.21 0.561

Total Kjeldahl nitrogen -0.008 -0.28 0.092 -0.011 -0.43 0.013

Total phosphorus 0 0 1.000 0.0002 0.14 0.452

/21*%5$1&+6,7(/21

Total inorganic nitrogen -0.013 -0.04 0.911 -0.029 -0.20 0.374

Dissolved inorganic nitrogen -0.013 -0.04 0.911 -0.035 -0.20 0.374

Total ammonia 0.0007 0.11 0.649 -0.003 0.20 0.374

Total organic nitrogen -0.009 -0.13 0.581 -0.008 -0.15 0.505

Total nitrogen -0.016 -0.02 1.000 -0.021 -0.17 0.440

Total Kjeldahl nitrogen -0.002 -0.09 0.733 -0.003 -0.13 0.581

Total phosphorus 0.002 0.41 0.023 0.0009 0.54 0.008
5HVXOWVRI1XWULHQW$QDO\VLV 

%2**<%5$1&+6,7(%2*

Total inorganic nitrogen 0.001 0.12 0.644 0.001 0.13 0.618

Dissolved inorganic nitrogen 0.002 0.11 0.653 -0.001 -0.07 0.812

Total ammonia 0 -0.02 1.000 0 0 1.000

Total organic nitrogen 0.005 0.07 0.877 0.018 0.30 0.311

Total nitrogen 0.002 0.07 0.881 0.004 0.20 0.515

Total Kjeldahl nitrogen -0.003 -0.08 0.880 0.005 0.04 1.000

Total phosphorus 0.003 0.60 0.149 0.0004 0.25 0.743

&522.('&5((.6,7(&52

Total inorganic nitrogen -0.006 -0.23 0.133 -0.009 -0.21 0.176

Dissolved inorganic nitrogen -0.010 -0.31 0.048 -0.011 -0.31 0.050

Total ammonia 0 0.17 0.221 0.001 0.30 0.055

Total organic nitrogen -0.005 -0.21 0.1655 -0.007 -0.32 0.042

Total nitrogen -0.011 -0.17 0.274 -0.017 -0.28 0.079

Total Kjeldahl nitrogen -0.001 -0.12 0.441 -0.006 -0.27 0.091

Total phosphorus 0 0.18 0.195 0.0003 0.15 0.343

+$0,/721&5((.6,7(+$0

Total inorganic nitrogen 0.004 0.11 0.524 0.003 0.15 0.362

Dissolved inorganic nitrogen 0.001 0.04 0.832 0.003 0.09 0.624

Total ammonia 0 0.03 0.880 -0.001 -0.15 0.360

Total organic nitrogen -0.008 -0.041 0.008 -0.003 -0.33 0.041

Total nitrogen -0.010 -0.24 0.137 -0.008 -0.22 0.183

Total Kjeldahl nitrogen -0.008 -0.40 0.195 -0.005 -0.40 0.011

Total phosphorus 0 0.15 0.195 0 0.18 0.131

-%&219(56(/$.($77+(380367$7,216,7(/+$0

Total inorganic nitrogen 0.007 0.41 0.155 ———

Dissolved inorganic nitrogen 0.006 0.50 0.063 — — —

Total ammonia 0.002 0.27 0.350 — — —

Total organic nitrogen -0.012 -0.45 0.115 — — —

Total nitrogen 0 0 1.000 — — —

Total Kjeldahl nitrogen -0.010 -0.27 0.367 — — —

Total phosphorus 0.002 0.32 0.248 — — —

7DEOH 5HVXOWVRIWKHVHDVRQDO.HQGDOOWDXWHVWIRUWUHQGVLQXQDGMXVWHGDQGIORZDGMXVWHGQXWULHQWFRQFHQWUDWLRQVDWVHOHFWHGVLWHVLQ

WKH&RQYHUVH/DNHZDWHUVKHG¥¦&RQWLQXHG

[Trends reported in units of milligrams per liter per year; bold values represent significant trends with p-value less than or equal to 0.05; <, less than; 

—, not applicable]

&RQVWLWXHQW 8QDGMXVWHG $GMXVWHG

7UHQG WDXYDOXH SYDOXH 7UHQG WDXYDOXH SYDOXH

Trend analysis results suggest nutrient 

contributions from land-use activities have little effect 

on the reported increase in the trophic state of Converse 

Lake from 1984 to 1995. Evidence for this is the 

decreasing or insignificant change in nutrient 

concentrations from 1990 to 1998 identified in the trend 

analysis in conjunction with little or no substantial 

change in land use in the watershed from 1985 to 1995 

(Reutebuch and others, 1997).

6SDWLDODQG7HPSRUDO'LVWULEXWLRQ

Nutrient concentrations at the tributary sites in 

the Converse Lake watershed showed only minor 

spatial variations (fig. 18). Long Branch had the 

greatest range in and median concentrations of total 

inorganic nitrogen (0.57 mg/L) and total nitrogen 

(0.93 mg/L) in the Converse Lake watershed. Collins 

Creek and the lake at the pump station (site LHAM) had 

the lowest median concentration of total nitrogen 

(0.43 mg/L). The lowest median concentrations of total 

inorganic nitrogen were at Boggy Branch (0.12 mg/L) 

and Converse Lake at the pump station (0.09 mg/L). 

Median concentrations of total Kjeldahl nitrogen were 

highest at Boggy Branch, Long Branch, and Big Creek 

(0.30 mg/L). Hamilton Creek, Juniper Creek, and 

Collins Creek had the lowest median concentrations of 
 $VVHVVPHQWRI:DWHU4XDOLW\&RQGLWLRQVLQWKH-%&RQYHUVH/DNH:DWHUVKHG0RELOH&RXQW\$ODEDPD¥

)LJXUH %R[SORWVRIWRWDO.MHOGDKOQLWURJHQWRWDOLQRUJDQLFQLWURJHQWRWDOQLWURJHQDQGWRWDOSKRVSKRUXVFRQFHQWUDWLRQVDWVHOHFWHGVLWHVLQ

WKH&RQYHUVH/DNHZDWHUVKHG¥
5HVXOWVRI1XWULHQW$QDO\VLV 

total Kjeldahl nitrogen (0.22 mg/L). Hamilton and 

Crooked Creeks had the highest median concentrations 

of total phosphorus (0.02 mg/L). The lake site at the 

pump station had similar median concentrations of 

total phosphorus (0.012).

Seasonal changes in nutrient concentrations 

related to biological uptake were not strongly evident at 

the tributary sites because of the added influence of 

streamflow. Within the lake, however, nutrient 

concentrations demonstrated seasonal patterns related 

to algal production (fig. 19). From 1996 to 1998, 

chlorophyll a levels in Converse Lake at the pump 

station increased from below 2 μg/L in February and 

March 1997 to a maximum of 9.7 μg/L in June 1997, 

indicating the period of greatest algal production. 

Beginning in August 1997, chlorophyll a levels 

gradually decreased to a minimum of below 0.1 μg/L in 

January and February 1998. A second peak also was 

noted in October 1997 when chlorophyll a levels 

increased to more than 6 μg/L. During the summer and 

)LJXUH 6HDVRQDOYDULDWLRQVLQ$FKORURSK\OODDQG%RUJDQLFDQGLQRUJDQLFQLWURJHQ

FRQFHQWUDWLRQVLQWKH&RQYHUVH/DNHZDWHUVKHG¥
 $VVHVVPHQWRI:DWHU4XDOLW\&RQGLWLRQVLQWKH-%&RQYHUVH/DNH:DWHUVKHG0RELOH&RXQW\$ODEDPD¥

fall of 1997 when algal production was greatest, total 

inorganic nitrogen concentration decreased to a 

minimum of less than 0.1 mg/L at the same time total 

organic nitrogen increased to a maximum of 

0.44 mg/L. This pattern suggests that during the peak 

of chlorophyll a production, inorganic forms of 

nitrogen were assimilated by photoplankton and 

converted to the organic form (fig. 19).

&RPSDULVRQRI1XWULHQW/RDGVZLWK7URSKLF6WDWHRI/DNH

The results of ADEM’s Reservoir Water Quality 

Monitoring Program indicated that the trophic state of 

Converse Lake apparently increased from a TSI value 

of 37 (oligotrophic) in 1985 to a TSI value of 62 

(eutrophic) in 1995 (table 17). The mean TSI for 1985 

to 1995 was 50, which placed the average trophic state 

of Converse Lake between eutrophic and mesotrophic 

conditions. In 1997, the TSI for the lake decreased to 

51 (Alabama Department of Environmental 

Management, 1999; table 17).

A simple trophic response of the lake to the 

nutrient loadings from the tributary subbasins was not 

evident during the study period. A surface phosphorus 

concentration of more than 0.024 mg/L in a lake is 

considered to indicate eutrophic conditions 

(Vollendweider, 1976), and would produce a Carlson’s 

TSI of over 50. To obtain a TSI of over 60, the total 

phosphorus and nitrogen concentrations must be 

greater than 0.048 and 0.333 mg/L, respectively, 

according to Carlson’s TSI (Carlson, 1977) and the 

Lake Evaluation Index (Porcella and others, 1980). 

Converse Lake at the pump station (site LHAM) had a 

mean total phosphorus concentration of 0.02 mg/L and 

a mean total nitrogen concentration of 0.43 mg/L, 

which categorizes the trophic state as mesotrophic 

during the study period 1990–98. These mean nutrient 

concentrations, however, do not include 1995 data 

7DEOH 6HDVRQDODQGDQQXDOFKDQJHLQWURSKLFSRWHQWLDODQGUHVSRQVHYDULDEOHVLQ&RQYHUVH/DNH¥

[—, no data; μg/L, microgram per liter; mL, milliliter; mg/L, milligram per liter; kg/d, kilogram per day]

7URSKLFSRWHQWLDO

RU

UHVSRQVHYDULDEOH

  

6SULQJ 6XPPHU 6SULQJ 6XPPHU 6SULQJ 6XPPHU

Carlson’s Trophic State Index — 51a

a

From Alabama Department of Environmental Management (1996).

— 62a — 51b

b

From Alabama Department of Environmental Management (1999).

Chlorophyll a (μg/L) — — — — 1.4c

2.9d

c

Average seasonal concentration at the lake for the pump station (USGS site LHAM).

d

Computed as an average of three sites in the Hamilton Creek embayment in Bayne and others (1998).

7.1c

8.0d

Phytoplankton density 

(organisms/mL)

— — — — 1,886d 1,485d

In-lake total phosphorus (mg/L) 0.013c 0.020c —— —c

0.009d

0.010c

0.013d

In-lake total orthophosphorus (mg/L) 0.007c 0.007c — — 0.005c

0.008d

0.005c

0.006d

In-lake total nitrogen (mg/L) 0.45c 0.42c — — 0.42c

0.39d

0.45c

0.37d

In-lake total inorganic nitrogen (mg/L) 0.15c 0.03c — — 0.13c

0.16d

0.01c

0.03d

Mean monthly total nitrogen loadinge

(kg/d)

e

From appendix 2; spring is the average of the monthly load rates for March, April, and May at Big, Hamilton, and Crooked Creeks; these averages 

are summed to get the mean monthly load. Summer is the average of the monthly load rates for June, July, and August.

107 101 259 176 156 314

Mean monthly total phosphorus loadinge

(kg/d)

3.99 3.41 17.5 7.05 7.39 19.3

Mean monthly total inorganic nitrogen 

loadinge

 (kg/d)

82.9 66.6 78.2 60.8 67.8 79.0

Land-use changesf

f

From Reutebuch and others (1997).

Forest re-growth Net loss of forest Forest re-growth
5HVXOWVRI1XWULHQW$QDO\VLV 

when the TSI was over 60 because no data were 

collected in the lake from 1993 to 1995. 

Nutrient concentrations and trophic response in 

the lake varied seasonally as well as annually 

(table 17). Trophic response variables and nutrient 

concentrations in the lake during the growing season 

were compared to the average monthly loading rates to 

the lake for spring and summer (computed from 

appendix 2 for Big, Crooked, and Hamilton Creeks) for 

1992, 1995, and 1997. In general, nutrient loads were 

least in the fall, and greatest in the winter and spring. 

Monthly total nitrogen and total phosphorus loading 

rates to the lake from the tributaries for 1997 were 

much higher than for 1992; however, the higher rates 

appeared to have minimal influence on the in-lake 

concentrations and trophic response (fig. 20; table 17). 

The only differences between the TSI in 1995, when a 

value of 62 was well within eutrophic conditions, and 

the other 2 years when the TSI was 51, are relatively 

high total phosphorus and total nitrogen loading rates 

of 17.5 and 259 kg/d, respectively, in the spring of 

1995. Although the rates of monthly loadings of total 

phosphorus and nitrogen were actually higher in the 

summer of 1997 (19.3 and 314 kg/d, respectively) than 

in the spring of 1995, the lake did not display a similar 

trophic response to the 1997 loadings. 

Although the relation between the annual input 

of nutrients and the in-lake phosphorus and nitrogen 

concentrations can be complex, an attempt was made to 

identify a relation between these two conditions. The 

annual in-lake phosphorus concentrations can be 

estimated by empirical models developed from 

information collected by several researchers for a 

variety of lake types in a variety of geographic and 

climatic regions (Kirchner and Dillon, 1975; 

Vollenweider, 1975; Larsen and Mercier, 1976; 

Reckhow and Clements, 1984). Vollenweider (1968, 

1969) developed an input-output (black box) model 

based on data from 20 natural lakes that established a 

correlation between annual areal nutrient loading and 

the mean lake depth for a given trophic state of the lake. 

Vollenweider (1975) modified the model to provide a 

measure of the phosphorus sedimentation or the 

amount of total phosphorus entering the lake that is 

)LJXUH 7HPSRUDOYDULDWLRQVLQQXWULHQWORDGLQJVWRWKHODNHGXULQJWKHJURZLQJVHDVRQDQGWKHODNH

UHVSRQVHWRWKHVHORDGLQJV
 $VVHVVPHQWRI:DWHU4XDOLW\&RQGLWLRQVLQWKH-%&RQYHUVH/DNH:DWHUVKHG0RELOH&RXQW\$ODEDPD¥

retained. This model computes the lake phosphorus 

concentration (P), in milligrams per liter, by the 

formula 

, (3)

where

L is the areal phosphorus loading (in grams per 

square meter per year),

vs is the apparent settling velocity (in meters per 

year),

z is the mean lake depth (in meters), and

 is the hydraulic residence time (in years). 

The areal phosphorus loading (L) is computed by 

the annual mass rate of phosphorus inflow (M; mean 

annual phosphorus load), in grams per year divided by 

the lake surface area (A), in square meters. The model 

assumes immediate and complete mixing of the input 

phosphorus in the lake, outflow concentrations equal to 

lake concentrations, phosphorus sedimentation rate 

proportional to its concentration, and negligible 

seasonal fluctuations in loading. 

Additional studies showed that the retention 

coefficient (R) could be described as 

(4)

where qs is the areal water loading, in meters per year 

(Chapra, 1975; Dillon and Kirchner, 1975). The areal 

water loading can be defined as the mean lake depth (z), 

in meters, divided by the hydraulic residence time ( ), 

in years (Reckhow, 1979). The general model then 

becomes:

. (5)

Vollenweider (1975) estimated the apparent settling 

velocity (vs) as 10 m/yr.

The mean annual total phosphorus load to 

Converse Lake was estimated to be 9,600 kg/yr 

(table 15) or 9,600,000 g/yr. The areal water loading 

(qs) is 9.98 m/yr (a mean depth of 14.4 ft is equivalent 

to 4.39 m; hydraulic residence time is 0.44 years). The 

lake surface area of 3,600 acres was converted to 

14,569,200 m2

. The areal water loading and apparent 

settling velocity were used as input to equation 4 to get 

a retention coefficient of 0.50. The mean annual total 

phosphorus load was used in equation 5 to provide an 

estimated annual in-lake phosphorus concentration of 

0.034 mg/L, which was about twice as high as the 

observed mean concentration of 0.020 mg/L 

(appendix 1). 

In summary, the lack-of-fit of the estimated 

in-lake phosphorus concentration from a simple inputoutput empirical model to the observed value in 

Converse Lake accentuates the need for a more robust 

model of lake water quality and trophic response. A 

more robust model would better explain the relation 

between annual nutrient contributions to Converse 

Lake from the tributaries and the lake’s ability to 

assimilate these contributions by biomass uptake, 

sedimentation, and outflow.

0,&52%,2/2*,&$/$66(660(17

Fecal indicator bacteria are useful in assessing 

water quality because they are strongly correlated to 

the presence of waterborne pathogens (Myers and 

Wilde, 1999). Simple field methods are available to 

culture and enumerate fecal indicator bacteria; 

therefore, areas of possible fecal contamination can be 

readily identified. Two groups of bacteria commonly 

used as indicators are the fecal coliforms and fecal 

streptococci. These groups usually occur in the 

intestines of warm-blooded animals, but they also are 

able to live in other environments. Escherichia coli 

(E. coli), a subgroup of the fecal coliforms, is enteric in 

origin. The presence of E. coli in water is direct 

evidence of fecal contamination from warm-blooded 

animals and the possible presence of pathogens 

(Dufour, 1977).

Giardia and Cryptosporidium are protozoan 

parasites that infect the digestive tracts of human 

beings and other animals. Excretion of infected animals 

may contain resistant cysts (Giardia) or oocysts 

(Cryptosporidium) that can persist in the environment 

and remain infective after leaving the host (Rose, 

1990).

Giardia is the cause of giardiasis, currently the 

most common waterborne disease in human beings 

(Hibler and Hancock, 1990). Cryptosporidium was first 

identified as a cause of disease in human beings in 1980 

(Rose, 1990). Symptoms of infection by these 

protozoans are diarrhea and abdominal discomfort 

(U.S. Environmental Protection Agency, 1993). 

P L

vs + z ⁄ τ = -------------------

τ

R vs

vs qs ( ) + = --------------------

τ

P Lτ

z = -----( ) 1 – R
0LFURELRORJLFDO$VVHVVPHQW 

Documented waterborne occurrences include a 1987 

outbreak in Carrollton, Ga., from a conventionally 

treated water supply (Rose, 1990), and another in 

Milwaukee, Wis., in 1993, which sickened 400,000 

people and killed more than 100 people (Conrad, 

1998). Because of the possibility of other outbreaks, 

the USEPA included testing of drinking water 

throughout the treatment and distribution process for 

Giardia cysts and Cryptosporidium oocysts in 

requirements for the Information Collection Rule (ICR; 

U.S. Environmental Protection Agency, 1999).

0LFURELRORJLFDO$QDO\VLV0HWKRGVDQG$SSURDFK

Water samples were analyzed for fecal coliform 

and fecal streptococci bacteria quarterly from 1990 to 

1996 and monthly from October 1996 to June 1998. 

Monthly analysis for E. coli was added in October 

1996. All bacteria were cultured and enumerated using 

membrane filtration techniques described in chapter 

7.1 of the USGS National Field Manual (Myers and 

Wilde, 1999). The following media were used for 

culturing: m-FC for fecal coliforms, KF for fecal 

streptococci, and m-TEC for E. coli. Results were 

reported in colonies per 100 milliliters of water. 

Basic summary statistics of fecal bacteria 

concentrations at each of the sites in the Converse Lake 

watershed were calculated (appendix 1). Boxplots of 

bacteria concentrations illustrate the range in 

concentrations found at each site. To further compare 

bacteria data to existing standards, the geometric mean 

concentration of each bacteria type was calculated. The 

geometric mean (G) of a series of numbers (x1, x2, 

x3...xn) is defined as follows:

. (6)

Geometric means are used in many water-quality 

standards and criteria for concentrations of bacteria 

because the effects of outlier values on the mean are 

reduced.

The trends in concentrations of fecal coliform 

and fecal streptococcus were determined at one lake 

and seven tributary sites from bacteria data collected 

during the period October 1990 to June 1998. Trend 

analysis was performed by using the same LOWESS 

statistical technique described in the previous section. 

Statistical significance was set for trend estimates with 

a p-value of less than 0.05.

The Converse Lake water-quality monitoring 

program included quarterly sampling for Giardia and 

Cryptosporidium at sites in the lake and in the watersupply system. Giardia sampling began in November 

1990, and Cryptosporidium sampling began in June 

1993. Water samples were shipped to BioVir 

Laboratories in Benicia, California, for analysis. Most 

of the samples collected during the study were 

analyzed for Giardia lamblia, the species of Giardia

known to infect human beings, and for 

Cryptosporidium by using Standard Method 9711B; 

FA (Greenberg and others, 1992b). The Information 

Collection Rule (ICR) method, EPA 600/R-95/178, 

was used to detect Giardia sp. and Cryptosporidium in 

samples collected during May 1998. ICR results are 

reported as cysts per 100 liters of raw water, rather than 

a direct count of cysts observed. Methods information 

and analytical data for June 1993 to May 1998 are 

presented in appendix 3. 

5HVXOWVRI0LFURELRORJLFDO$QDO\VLV

The USEPA and the ADEM established 

standards and criteria for concentrations of fecal 

coliform bacteria for waters of varying uses (table 18). 

The ADEM established a use-classification system for 

State waters. Tributaries to Converse Lake are 

designated as suitable for fish and wildlife habitats, and 

the lake is classified as a public water supply.

The drinking-water standards are the maximum 

allowable levels of fecal bacteria in finished water, and 

are enforceable. The ADEM and USEPA criteria values 

are suggested limits or goals for fecal bacteria. All 

water-use classifications have criteria based on the 

maximum geometric mean bacterial density of five or 

more samples collected over 30 days at intervals of not 

less than 24 hours. Seasonal geometric mean criteria, 

which are effective June through September, apply to 

fish and wildlife and public water-supply uses. Even 

though geometric mean criteria were developed for use 

with several samples per month, the levels can provide 

a benchmark to assess the water quality of the Converse 

Lake watershed. Public water-supply, fish and wildlife, 

and agricultural and industrial water-supply water-use 

classifications also have maximum single-sample fecal 

coliform concentrations. 

The USEPA-suggested criteria for E. coli for 

areas where swimming and whole-body contact sports 

occur are included in table 18. The USEPA suggests 

that the geometric mean of samples collected at a site 

G x1x2x3...xn ( )1 n⁄ =
 $VVHVVPHQWRI:DWHU4XDOLW\&RQGLWLRQVLQWKH-%&RQYHUVH/DNH:DWHUVKHG0RELOH&RXQW\$ODEDPD¥

should not exceed 126 col/100 mL, and that singlesample concentrations should not exceed 235 col/100 

mL in designated beach areas, or 576 col/100 mL in 

areas where waters are infrequently used for wholebody contact recreation (U.S. Environmental 

Protection Agency, 1986).

Summary statistics were calculated for each 

bacteria type at each site (appendix 1). Boxplots of the 

concentration data for each bacteria type, sorted by site, 

represent the data distribution graphically (fig. 21). 

Percentile values of bacterial concentrations were used 

to describe how often individual measurements 

exceeded criteria levels. Seventy-five percent of all 

measured fecal coliform concentrations at each of the 

sites were less than 1,000 col/100 mL, the geometric 

mean criterion for public water supply and fish and 

wildlife water uses (red line, fig. 21A). Fifty percent of 

all measured fecal coliform concentrations at all sites 

except JUN and CRO were less than 200 col/100 mL, 

the geometric mean criterion for swimming and wholebody contact water uses (blue line, fig. 21A). 

Maximum fecal coliform levels at the two lake sites 

were below public water-supply criteria, but the 

maximum at site LHAM was above the criterion for 

swimming. At each of the tributary sites, at least 

50 percent of all measured E. coli concentrations 

exceeded 126 col/100 mL, the geometric mean 

criterion for swimmable waters (blue line, fig. 21C). At 

sites COL, CRO, HAM, and JUN, at least 50 percent of 

all measured E. coli concentrations exceeded 

235 col/100 mL, the single-sample criterion for 

designated beach areas (brown line, fig. 21C). At site 

JUN, 50 percent of all measured concentrations of 

E. coli exceeded 576 col/100 mL, the single-sample 

limit for infrequent body contact (green line, fig. 21C). 

Concentrations of all bacteria types were lower at the 

two lake sites (LCRO and LHAM) than at the tributary 

sites (fig. 21). Also, the concentration range of E. coli

appears to be higher at Juniper Creek (site JUN) than at 

other sites in the watershed. 

Boxplots illustrate the seasonal concentrations of 

each bacteria type for all sites (fig. 22). Fecal coliform 

and E. coli had only minor variations in concentrations 

between seasons, whereas fecal streptococcus 

concentrations were somewhat greater during spring 

and summer. The difference in concentrations between 

seasons is probably due to temperature changes, which 

affect the survival rates of the fecal streptococci.

Median concentrations of each bacteria type 

were calculated by season for each site to examine 

seasonal effects on bacteria concentrations (table 19). 

At the majority of the sites, fecal coliform bacteria 

seem to be more abundant in summer than during the 

other seasons. Fecal streptococci were more abundant 

during spring and summer at individual sites.

7DEOH 6WDQGDUGVDQGFULWHULDIRUFRQFHQWUDWLRQVRIIHFDOEDFWHULDVHWE\WKH$ODEDPD'HSDUWPHQWRI(QYLURQPHQWDO0DQDJHPHQW

DQGWKH86(QYLURQPHQWDO3URWHFWLRQ$JHQF\IRUYDULRXVZDWHUXVHFODVVLILFDWLRQV86(QYLURQPHQWDO3URWHFWLRQ$JHQF\

$ODEDPD'HSDUWPHQWRI(QYLURQPHQWDO0DQDJHPHQW

[—, not applicable]

7\SHRIEDFWHULD 'ULQNLQJZDWHU

VWDQGDUG

)HFDOEDFWHULDOFRQFHQWUDWLRQVE\ZDWHUXVHFODVVLILFDWLRQV

LQFRORQLHVSHUPLOOLOLWHUV

2XWVWDQGLQJ

$ODEDPD

ZDWHU

3XEOLFZDWHU

VXSSO\

6ZLPPLQJDQG

RWKHUZKROHERG\

ZDWHUFRQWDFW

VSRUWV

)LVK

DQG

ZLOGOLIH

$JULFXOWXUDODQG

LQGXVWULDOZDWHU

VXSSO\

Fecal coliform 0 200a

a

Bacterial concentrations shall not exceed a geometric mean of this value. The geometric mean shall be calculated from no less than five 

samples collected at a given station over a 30-day period at intervals not less than 24 hours.

1,000a

(200)b

2,000c

b

Values in parentheses are seasonal geometric mean limits effective during June through September to account for incidental water contact 

and recreational uses. c

Maximum bacterial concentration not to be exceeded in any sample.

200a 1,000a

(200)b

2,000c

2,000a

4,000c

Escherichia coli 0 — — 126a

235 to 576d

dRange in U.S. Environmental Protection Agency recommended single-sample maximum allowable density for whole-body contact 

recreation for different frequencies of use, from designated beach areas to infrequently used whole-body contact recreational areas.

— —
0LFURELRORJLFDO$VVHVVPHQW 

)LJXUH %R[SORWVVKRZLQJUDQJHVRI$IHFDOFROLIRUP%IHFDOVWUHSWRFRFFXVDQG&(FROLFRQFHQWUDWLRQVDWVHOHFWHGVLWHVLQWKH

&RQYHUVH/DNHZDWHUVKHG¥
 $VVHVVPHQWRI:DWHU4XDOLW\&RQGLWLRQVLQWKH-%&RQYHUVH/DNH:DWHUVKHG0RELOH&RXQW\$ODEDPD¥

)LJXUH %R[SORWVVKRZLQJVHDVRQDO$IHFDOFROLIRUP%IHFDOVWUHSWRFRFFXVDQG&(FROLFRQFHQWUDWLRQVDWVHOHFWHGVLWHVLQWKH

&RQYHUVH/DNHZDWHUVKHG¥
0LFURELRORJLFDO$VVHVVPHQW 

 Seasonal median values also can be compared to 

criteria to help determine when exceedances occur. At 

all sites in the watershed, median fecal coliform 

concentrations measured in spring were less than 

200 col/100 mL, the geometric mean criterion for 

swimmable waters. Median fecal coliform 

concentrations measured in summer were greater than 

or equal to 200 col/100 mL at sites BIG, JUN, COL, 

LON, BOG, and CRO. Median fecal coliform 

concentrations in autumn were greater than 

200 col/100 mL at sites JUN and CRO. In winter, only 

site JUN had a median fecal coliform concentration 

above 200 col/100 mL. None of the seasonal median 

fecal coliform concentrations was greater than 

1,000 col/100 mL, the public water-supply and fish and 

wildlife geometric mean criterion. Median values of 

fecal coliform concentrations in the lake sites were 

below all criteria throughout the year.

Median E. coli concentrations exceeded the 

geometric mean criterion of 126 col/100 mL at 

sites BIG, JUN, COL, BOG, CRO, and HAM during 

all seasons, and at site LON during summer and winter. 

Median E. coli concentrations exceeded the designated 

beach single-sample criterion of 235 col/100 mL at 

7DEOH 6HDVRQDOPHGLDQEDFWHULDOFRQFHQWUDWLRQVIRUVHOHFWHGVLWHVLQWKH&RQYHUVH/DNHZDWHUVKHG¥

[col/100 mL, colonies per 100 milliliters]

6SULQJ 6XPPHU $XWXPQ :LQWHU

6LWHODEHO

ILJ

1XPEHU

RI

REVHUYDWLRQV

0HGLDQ

1XPEHU

RI

REVHUYDWLRQV

0HGLDQ

1XPEHU

RI

REVHUYDWLRQV

0HGLDQ

1XPEHU

RI

REVHUYDWLRQV

0HGLDQ

)HFDOFROLIRUPVFROP/

BIG 13 69 14 200 15 130 16 145

JUN 11 190 13 340 14 300 16 460

COL 10 120 12 240 14 180 16 145

LON 10 105 10 250 10 145 13 110

BOG 9 150 10 205 10 160 13 170

CRO 13 120 14 360 15 310 17 180

LCRO 3 27 5 2 6 7 6 24

HAM 12 140 13 160 15 140 17 160

LHAM 8 2 10 6 12 5 12 13

)HFDOVWUHSWRFRFFLFROP/

BIG 13 260 15 520 16 235 16 86

JUN 12 670 14 935 13 250 16 295

COL 12 630 14 370 14 260 16 245

LON 9 660 11 700 10 295 12 102

BOG 9 540 11 500 10 375 13 140

CRO 13 700 15 740 16 530 17 220

LCRO 3 9 5 1 6 6 6 13

HAM 13 490 15 550 16 170 17 190

LHAM 9 6 11 2 13 3 11 6

(VFKHULFKLDFROLFROP/

BIG 3 140 5 200 6 160 5 160

JUN 3 790 5 1,600 6 485 6 2,150

COL 3 170 5 1,500 6 210 6 620

LON 3 83 5 290 5 120 6 140

BOG 3 130 5 210 6 240 6 190

CRO 3 350 5 540 6 370 5 300

LCRO 2 24 5 3 6 7 6 48

HAM 3 480 5 280 6 195 6 500

LHAM 3 22 5 3 3 4 3 12
 $VVHVVPHQWRI:DWHU4XDOLW\&RQGLWLRQVLQWKH-%&RQYHUVH/DNH:DWHUVKHG0RELOH&RXQW\$ODEDPD¥

sites JUN and CRO during all seasons, at site HAM 

during spring, summer, and winter, at site COL during 

summer and winter, at site LON during summer, and at 

site BOG during autumn (table 19). Median 

concentrations exceeded the single-sample maximum 

of 576 col/100 mL for infrequently used whole-body 

contact recreation areas at site JUN during spring, 

summer, and winter and at site COL during summer. 

For all seasons, median E. coli concentrations at lake 

sites LCRO and LHAM were below all criteria. 

Median concentrations of E. coli were lower at the lake 

sites in summer and autumn than during winter and 

spring, possibly because low flows in the tributaries 

prevented the bacteria from being transported to the 

lake before they naturally died off. 

For comparison to criteria, geometric means of 

the measured concentrations of each bacteria type were 

calculated. Geometric means are summarized in 

table 20, and geometric mean bacterial density is 

shown in figure 23.

Geometric mean concentrations of fecal 

coliform for the entire period of record were below all 

criteria levels at tributary sites BIG, LON, and HAM, 

and lake sites LCRO and LHAM (fig. 23A). Sites JUN, 

COL, BOG, and CRO exceeded the whole-body 

contact geometric mean criterion of 200 col/100 mL. 

The geometric mean concentrations of fecal 

streptococci for the entire period of record are shown in 

figure 23B. Though no criteria currently (2001) exist 

for fecal streptococci, the high geometric mean 

concentrations found at sites JUN, COL, and CRO 

should be noted, as well as the low geometric means at 

the two lake sites, LCRO and LHAM. 

The geometric mean of E. coli concentrations for 

the period October 1996 to June 1998 at all tributary 

sites exceeded the whole-body contact geometric mean 

criterion of 126 col/100 mL; however, the geometric 

mean concentrations at the lake sites, LCRO and 

LHAM, were well below all criteria levels (fig. 23C). 

Sites JUN, COL, BOG, CRO, and HAM had geometric 

mean concentrations greater than the whole-body 

contact single-sample exceedance criterion for beach 

areas (235 col/100 mL). Site JUN had higher 

concentrations of E. coli than the other tributary sites 

(table 20). 

To determine if criteria exceedances for fecal 

coliform were occurring at the same sites as E. coli

exceedances, geometric mean concentrations for fecal 

coliform concentrations were determined for the same 

time period as that for the E. coli concentrations 

(figs. 23C, D). Six of the seven tributary sites exceeded 

the whole-body contact geometric mean criterion of 

200 col/100 mL for fecal coliform. The geometric 

mean fecal coliform density of 921 col/100 mL at 

Juniper Creek (site JUN) approached the public watersupply and the fish and wildlife geometric mean 

criteria of 1,000 col/100 mL.

Concentrations of fecal bacteria in the tributaries 

were elevated during the study period and may be cause 

for concern, especially in Juniper Creek. 

Concentrations of indicator bacteria at the lake sites, 

however, were below all criteria, indicating the lake 

water was an acceptable source for drinking-water 

supply. Trend analyses of the fecal coliform and fecal 

streptococcus data showed significant increases in 

concentrations at Juniper Creek (site JUN; table 21) 

from 1990 to 1998. These trends are of particular 

concern because median fecal coliform concentrations 

at Juniper Creek were already above the whole-body 

contact criteria during the same period (appendix 1). 

7DEOH *HRPHWULFPHDQVRIEDFWHULDOFRQFHQWUDWLRQVDWVLWHVLQWKH&RQYHUVH/DNHZDWHUVKHGIRUWKHSHULRG

2FWREHU¥-XQH

7\SHRIEDFWHULD &RQFHQWUDWLRQVE\VLWHLQFRORQLHVSHUPLOOLOLWHUV

%,* -81 &2/ /21 %2* &52 /&52 +$0 /+$0

Fecal coliform 168 358 202 150 225 257 10 165 7

Fecal streptococci 263 573 407 361 361 522 7 346 5

Escherichia coli 216 1,185 454 173 262 375 10 272 8

Fecal coliform 1996–98 245 921 395 199 285 313 10 231 10
0LFURELRORJLFDO$VVHVVPHQW 

)LJXUH 5DQJHVLQJHRPHWULFPHDQFRQFHQWUDWLRQVRIIHFDOFROLIRUPDQGIHFDOVWUHSWRFRFFXVIRU¥DQG(FROLDQGIHFDOFROLIRUPIRU

¥
 $VVHVVPHQWRI:DWHU4XDOLW\&RQGLWLRQVLQWKH-%&RQYHUVH/DNH:DWHUVKHG0RELOH&RXQW\$ODEDPD¥

Spearman rank correlation coefficients for 

median concentrations of each type of bacteria and the 

percentage of each type of land use were calculated to 

identify possible links between land use and fecal 

contamination. Scatter plots are useful to illustrate the 

relations between the percentages of various land-use 

types and the median concentrations of selected 

bacteria (fig. 24). No significant correlations between 

percentages of land-use types and median 

concentrations of bacteria were observed. 

Protozoan monitoring detected very few 

encysted protozoans during the study period. Assay 

results from November 1990 through August 1992 are 

presented in the report by Journey and others (1995). 

Results from June 1993 to May 1998 are shown in 

appendix 3 and summarized here. In August 1993, one 

Giardia cyst was found during the Cryptosporidium

assay of the site LHAM sample. The species of Giardia

could not be determined from this assay, and no 

Giardia cysts were found during the Giardia lamblia

assay. One Cryptosporidium oocyst was detected in the 

January 1996 sample from the holding reservoir at the 

filtration plant. In June 1996, six Giardia cysts and one 

Cryptosporidium oocyst were detected at Highway 98, 

and six Giardia cysts were detected at site LHAM.

The low number of Giardia cyst and 

Cryptosporidium oocyst detections in the water 

samples makes it difficult to draw conclusions about 

actual concentrations of these pathogenic protozoans in 

the water supply or about factors that may influence 

7DEOH 5HVXOWVRIWKHVHDVRQDO.HQGDOOWDXWHVWIRUWUHQGVLQXQDGMXVWHGDQGIORZDGMXVWHGEDFWHULDOFRQFHQWUDWLRQVDWVHOHFWHGVLWHV

LQWKH&RQYHUVH/DNHZDWHUVKHG¥

[Trends reported in units of colonies per 100 milliliters per year; bold values represent significant trends with p-value less than or equal to 0.05; 

—, not applicable]

)HFDOEDFWHULD 8QDGMXVWHG $GMXVWHG

7UHQG WDXYDOXH SYDOXH 7UHQG WDXYDOXH SYDOXH

%,*&5((.6,7(%,*

Fecal coliform 8.25 0.27 0.090 6.075 0.11 0.5279

Fecal streptococcus 15.17 0.16 0.3250 44.42 0.20 0.2332

-81,3(5&5((.6,7(-81

Fecal coliform 76.67 0.40 0.0198 52.55 0.28 0.1150

Fecal streptococcus 96.61 0.42 0.0161 82.15 0.42 0.0161

&2//,16&5((.6,7(&2/

Fecal coliform 31.93 0.27 0.1319 19.95 0.18 0.3334

Fecal streptococcus 64.50 0.23 0.2165 -25.50 -0.21 0.2530

/21*%5$1&+6,7(/21

Fecal coliform 11.67 0.33 0.1198 8.371 0.22 0.3203

Fecal streptococcus -2.067 -0.08 0.7923 20.35 0.13 0.5808

%2**<%5$1&+6,7(%2*

Fecal coliform -8.071 -0.07 0.8241 -4.526 -0.09 0.7404

Fecal streptococcus -24.80 -0.04 0.9121 -45.12 -0.17 0.4395

&522.('&5((.6,7(&52

Fecal coliform 10.00 0.14 0.4390 12.02 0.20 0.2509

Fecal streptococcus 60.00 0.21 0.2068 46.00 0.18 0.2998

+$0,/721&5((.$7612:52$'6,7(+$0

Fecal coliform 7.750 0.14 0.3989 9.150 0.14 0.3989

Fecal streptococcus -15.83 -0.15 0.3596 -36.02 -0.30 0.0583

+$0,/721&5((.$7380367$7,216,7(/+$0

Fecal coliform -0.7500 -0.16 0.6203 ———

Fecal streptococcus -0.1667 -0.20 0.5030 — — —
0

LFURELRORJLFDO$VVHVVPHQW

)LJXUH$ 6FDWWHUSORWVVKRZLQJUHODWLRQVEHWZHHQSHUFHQWDJHVRIYDULRXVODQGXVHW\SHVDQGPHGLDQIHFDOFROLIRUPFRQFHQWUDWLRQVDWVLWHVLQ


$VVHVVPHQWRI:DWHU4XDOLW\&RQGLWLRQVLQWKH-%&RQYHUVH/DNH:DWHUVKHG0RELOH&RXQW\$ODEDPD¥

MEDIAN FECAL STREPTOCOCCUS CONCENTRATION, IN COLONIES PER 100 MILLILITERS

)LJXUH% 6FDWWHUSORWVVKRZLQJUHODWLRQVEHWZHHQSHUFHQWDJHVRIYDULRXVODQGXVHW\SHVDQGPHGLDQIHFDOVWUHSWRFRFFXVFRQFHQWUDWLRQVDWV
0

LFURELRORJLFDO$VVHVVPHQW

)LJXUH& 6FDWWHUSORWVVKRZLQJUHODWLRQVEHWZHHQSHUFHQWDJHVRIYDULRXVODQGXVHW\SHVDQGPHGLDQ(FROLFRQFHQWUDWLRQVDWVLWHVLQWKH&RQ
 $VVHVVPHQWRI:DWHU4XDOLW\&RQGLWLRQVLQWKH-%&RQYHUVH/DNH:DWHUVKHG0RELOH&RXQW\$ODEDPD¥

these concentrations. Although concentrations of 

Giardia and Cryptosporidium seem to be small in the 

water supply, false negatives are possible with the 

sampling methods that were used. According to Rose 

(1990), “The interpretation of negative samples may be 

difficult and does not necessarily signify the absence of 

contaminating oocysts.” More detections of Giardia

and Cryptosporidium in Converse Lake occurred 

during spring and summer (May, June, and August) 

than during autumn and winter, suggesting a 

seasonality in the occurrence of cysts and oocysts. 

Continued monitoring of protozoan pathogen 

concentrations at the intake to the drinking-water 

system combined with bacteriological sampling may 

help define relations between concentrations of 

bacteria and pathogens in the watershed.

In summary, monitoring in the Converse Lake 

watershed for fecal contamination shows that some 

tributaries to Converse Lake have concentrations of 

fecal bacteria above existing criteria for whole-body 

contact uses. Concentrations of bacteria at lake 

sites LCRO (mouth of Crooked Creek) and LHAM 

(Hamilton Creek at pump station) were well below all 

criteria levels. Elevated concentrations of bacteria in 

the tributaries did not seem to cause elevated levels in 

the lake. 

Juniper Creek (site JUN) had the highest 

geometric mean concentrations for all bacteria types 

during the study. Trend analyses show that flowadjusted concentrations of fecal streptococcus were 

increasing at site JUN during the 8 years of data 

collection. This apparent increasing trend in bacteria is 

cause for concern because the current (2001) bacteria 

levels in Juniper Creek are above the suggested criteria 

levels.

Detections of Giardia and Cryptosporidium

were few at sites in the lake and the raw-water intake 

during the monitoring period. The low number of 

detections makes it difficult to draw any conclusions 

about actual cyst concentrations in the water supply. 

Most of the detections occurred during the summer 

months, but so few cysts were detected that it is not 

clear if there is a seasonal influence on cyst density. 

25*$1,&&$5%21&+$5$&7(5,=$7,21

The naturally occurring organic carbon present 

in Converse Lake and its tributaries was characterized 

by estimating the reactivity and identifying the general 

source of the organic carbon. This characterization was 

based on past research of the factors that control the 

reactive nature and occurrence of organic matter in a 

watershed (Rook, 1977; de Leer and Erkelens, 1989; 

Amy and others, 1990; Miller and others, 1990; 

Reckhow and others, 1990; Nieminski and others, 

1993; Krasner and others, 1994; Aiken and Cotsaris, 

1995; Singer and others, 1995; Korshin and others, 

1996; Summers and others, 1996). An understanding of 

the reactive nature and source of organic carbon is 

needed to minimize the formation of disinfection byproducts (DBPs), which are produced from a reaction 

between naturally occurring organic matter and 

chlorine when chlorine is added to water for 

disinfection. The DBPs of regulatory concern are 

trihalomethanes (THMs) and haloacetic acids (HAAs). 

This study addresses only THM formation—the sum of 

chloroform (CHCl3), bromoform (CHBr3), 

bromodichloromethane (CHBrCl2), and 

dibromochloromethane (CHBr2Cl).

Organic matter in raw water is measured by 

determining the concentrations of total organic carbon 

(TOC) and dissolved organic carbon (DOC). TOC is 

the total of all organic carbon compounds, both 

dissolved and particulate, present in the raw water. 

DOC is the organic carbon that passes through a 0.45-

micron filter and may include colloidal organic matter. 

Oxidants, including chlorine, chlorine dioxide, and 

monochloroamine, are added to raw water during water 

treatment for the purpose of disinfecting the water 

supply. In addition to disinfection, chlorine reacts by 

cleaving the aromatic rings of organic carbon 

compounds in the water and releasing halogenated byproducts that are a potential health risk. However, not 

all of the organic carbon compounds in organic matter 

have aromatic rings and, thus, may be less reactive and 

less a risk for THM formation. 

Hydrology, soil type, and climate of the 

watershed affect the occurrence of naturally occurring 

reactive organic matter which, in turn, influences the 

occurrence of DBP precursors in the water supply 

(Aiken and Cotsaris, 1995). Hydrologic processes 

include transport of terrestrially derived, tannin- and 

lignin-rich organic carbon into a stream, river, or lake 

by overland flow and flushing of the shallow soil zone 

during rain events. Terrestrially derived 

(allochthonous) organic carbon compounds include 

humic and fulvic acids. These acids generally 

constitute about 50 to 60 percent of the dissolved 

organic carbon found in river and lake waters; these 

acids also have a high reactivity with chlorine (de Leer 
2UJDQLF&DUERQ&KDUDFWHUL]DWLRQ 

and Erkelens, 1989). Algal growth and microbial 

processes occur within the aquatic environment 

(autochthonous) and produce organic carbon 

compounds, such as carbohydrates, pigments, proteins, 

lipids, polysaccharides, and amino acids, which are not 

as reactive with chlorine (de Leer and Erkelens, 1989). 

Algal and microbial processes can dominate in slower 

moving waters, such as reservoirs. Ground-water 

discharge is a negligible source of organic carbon 

because concentrations generally are low. 

Soils can influence the transport of organic 

carbon to streams or lakes. Iron-rich lateritic soils tend 

to adsorb the organic carbon in the deeper soil layers 

causing the organic carbon to slowly leach into the 

stream. Sandy soils do not hold or sorb the organic 

carbon as readily, thus allowing for quick flushing 

during rain events. 

 The tendency of naturally occurring organic 

carbon to react with chlorine is a function of several 

factors (Aiken and Cotsaris, 1995). Source, 

geochemistry, and degradation by microbial processes 

influence the reactivity of the organic carbon. Research 

on organic geochemistry of naturally occurring organic 

matter has shown that the ability of the organic carbon 

to react with chlorine depends, in part, on the 

aromaticity (the number of aromatic rings present in 

the organic matter) and the carbon-to-nitrogen ratio in 

the organic carbon (table 22). In general, terrestrial, 

lignin-rich vegetation (such as trees) has a higher 

carbon content and, consequently, higher carbon-tonitrogen ratios than aquatic vegetation (such as 

emergent wetland plants); therefore, organic matter 

that is derived from terrestrial sources tends to react 

more readily with chlorine to form DBPs than organic 

matter from aquatic sources.

Absorption of light by natural waters provides a 

semiqualitative indicator of the concentration of 

naturally occurring organic matter in the water, 

especially ultraviolet light absorbance at 

254 nanometer wavelength (Korshin and others, 1997). 

Most organic matter molecules that absorb light at 

ultraviolet ranges are aromatic groups, including 

phenols and aromatic acids (found in high 

concentrations in humic and fulvic acids). Previous 

studies have shown a good correlation between 

ultraviolet light absorbance at 254 nanometers and 

trihalomethane-formation potential (Reckhow and 

others, 1990).

2UJDQLF&DUERQ$QDO\VLV0HWKRGVDQG$SSURDFK

 Sampling water for organic carbon, which may 

be precursors to disinfection by-products, consisted of 

collecting monthly surface-water samples over an 

18-month period at seven tributary sites and two lake 

7DEOH *HQHUDOJHRFKHPLFDOFKDUDFWHULVWLFVRIQDWXUDOO\RFFXUULQJRUJDQLFFDUERQFRPSRXQGVLQVXUIDFHZDWHUGHULYHGIURP

OLJQLQGHULYHGDOORFKWKRQRXVRUPLFURELDODOJDOGHULYHGDXWRFKWKRQRXVVRXUFHVPRGLILHGIURP$LNHQDQG&RWVDULV

6RXUFHRIQDWXUDOO\RFFXUULQJRUJDQLFPDWWHULQULYHUVDQGODNHV

/LJQLQGHULYHG

DOORFKWKRQRXV

0LFURELDODOJDOGHULYHG

DXWRFKWKRQRXV

Low in nitrogen High in nitrogen

High in aromatic carbon; low in aliphatic carbon Low in aromatic carbon; high in aliphatic carbon

High phenolic content Low phenolic content

Greater absorbance of ultraviolet light at 254 nanometers Less absorbance of ultraviolet light at 254 nanometers

More reactive Less reactive
 $VVHVVPHQWRI:DWHU4XDOLW\&RQGLWLRQVLQWKH-%&RQYHUVH/DNH:DWHUVKHG0RELOH&RXQW\$ODEDPD¥

7DEOH 7\SHVDQGSRWHQWLDOVRXUFHVRIRUJDQLFFDUERQLQ

VXUIDFHZDWHUVDPSOHVFROOHFWHGLQWKH&RQYHUVH/DNHZDWHUVKHG

6DPSOHVPHDVXUHG 3RWHQWLDOVRXUFHV

Total and dissolved organic 

carbon

Concentrations of all organic 

carbon compounds 

Tannin and lignin Estimate of the amount of 

organic carbon compounds 

derived from terrestrial plant 

material (humics)

Chlorophyll a, b Estimate of the amount of algae 

in water

Ultraviolet absorbance at 

254 nanometers

Estimate of the reactivity of the 

organic carbon

Trihalomethane-formation 

potential

Measure of the amount of 

trihalomethanes formed as a 

result of chlorination

Trihalomethane yield Measure of the amount of 

trihalomethanes formed per 

unit of organic carbon

Specific absorbance (ultraviolet absorbance/

dissolved organic carbon)

Estimate of the humic content of 

the dissolved organic carbon

sites in the Converse Lake watershed (table 23). 

Samples were analyzed for TOC, DOC, tannin and 

lignin, and chlorophyll a and b concentrations 

(site LHAM only) at the USGS Laboratory in Ocala, 

Florida. Field blanks of organic-free water were 

processed for TOC, DOC, and tannin and lignin 

following the same quality assurance and quality 

control procedures used for surface-water samples. 

Streamflow, water temperature, dissolved oxygen 

(concentration and percent saturation), pH, alkalinity, 

Secchi disk depth (at lake sites), and specific 

conductance were measured in the field at the time of 

sampling. 

2041 ultraviolet-visible spectrum (UV-Vis) 

spectrophotometer and a 4-cell changer that contained 

quartz cells with 1-cm pathlength. The filtered sample 

data represented the reactivity of DOC; the unfiltered 

samples represented the reactivity of TOC. Each sample 

was analyzed in triplicate, and the UVA results were 

averaged to obtain the final results for the filtered 

(UVA-DOC) and unfiltered (UVA-TOC) samples, 

which had units of absorbance per centimeter-1 (cm-1). 

Laboratory blanks of organic-free water were analyzed 

in all cells before and after sample analysis for quality 

assurance and quality control. Specific ultraviolet 

absorbance (SUVA) was determined as the ratio of 

ultraviolet absorbance to DOC concentration in units of 

liters per milligram per centimeter.

Characterizing the origin of the reactive organic 

carbon at each tributary and lake site involved several 

interpretive approaches, including statistical, graphical, 

and spatial analyses of the data. The results were used 

to evaluate the reactivity of the organic carbon and the 

relation of sources and spatial distribution of the 

reactive organic carbon to land use in the watershed. 

Statistical summaries of these data are presented in 

appendix 1. The tendency of the organic carbon at each 

site to react with chlorine to form disinfection byproducts was estimated by the UVA of the water sample 

at that site. Trihalomethane-formation potential was 

compared to UVA levels for verification of the UVAestimated reactivity of the organic carbon. Seasonal 

variability of reactive organic carbon in the lake and its 

tributaries was determined. Spearman rho correlation 

coefficients (previously described) were determined for 

the total and dissolved organic carbon concentrations, 

tannin and lignin (terrestrial plant material) 

concentrations, Secchi disk depth, and chlorophyll 

(aquatic plant material) concentrations to identify a 

probable source of the organic carbon (table 23). The 

spatial distribution of median TOC, DOC, tannin and 

lignin, and UVA levels were determined to identify the 

subbasin(s) contributing the greatest amount of reactive 

organic carbon to the lake.

5HVXOWVRI2UJDQLF&DUERQ$QDO\VLV

 The USEPA set a maximum contaminant level 

(MCL), effective in 1999, of 80 μg/L for total THMs in 

finished water (U.S. Environmental Protection Agency, 

1998), a reduction from the previous MCL of 100 μg/L. 

The MAWSS submitted quarterly monitoring 

information to the USEPA on the formation of THM in 

Quarterly surface-water samples were collected at 

the three continuous-record stations and at the one lake 

site at the pumping station, and were analyzed for 

trihalomethane-formation potential (THM-FP) at the 

USGS National Water Quality Laboratory in Denver, 

Colorado. Surface-water samples were analyzed 

according to Standard Method 5710 by purge and trap 

gas chromatography/mass spectroscopy and by solidphase microextraction for THMs (Symons and others, 

1981; Greenberg and others, 1992a). Filtered and 

unfiltered water samples were analyzed for ultraviolet 

absorbance at 254 nanometers (UVA) at the USGS 

Alabama District Office using a Bucks Scientific CE 
5HVXOWVRI2UJDQLF&DUERQ$QDO\VLV 

treated water samples collected from July 1997 to June 

1988, as mandated in the ICR of the Safe Drinking 

Water Act (U.S. Environmental Protection Agency, 

1996a,b,c). Municipal surface-water supply systems in 

Birmingham, Tuscaloosa, and Huntsville, Alabama, 

also submitted quarterly THM information. During the 

monitored period, the treated water from the MAWSS 

(Mobile) and Birmingham exceeded the 80-μg/L MCL 

during the summer and fall (fig. 25; U.S. 

Environmental Protection Agency, 2000). The results 

of the monitoring indicated that the greatest mean 

THM concentration was in treated water from the 

MAWSS (76 μg/L), followed by mean THM 

concentrations in treated water for Birmingham 

(67 μg/L), Tuscaloosa (54 μg/L), and Huntsville 

(46 μg/L). These mean THM concentrations are 

similar to those reported for municipal water supplies 

in North Carolina (Singer and others, 1995), but are 

lower than levels reported in Ohio and Florida 

(Summers and others, 1996; fig. 26). Nieminski and 

others (1993) reported a range of 1 to 97 μg/L of THM 

concentrations in treated water from 35 water-supply 

utilities in Utah.

)LJXUH 4XDUWHUO\DQGPHDQUHVXOWVRIPRQLWRULQJIRUWULKDORPHWKDQHFRQFHQWUDWLRQVLQWUHDWHGZDWHUDW

IRXUPXQLFLSDOZDWHUVXSSOLHVLQ$ODEDPDDVSDUWRIWKH,QIRUPDWLRQ&ROOHFWLRQ5XOHUHTXLUHPHQWV
 $VVHVVPHQWRI:DWHU4XDOLW\&RQGLWLRQVLQWKH-%&RQYHUVH/DNH:DWHUVKHG0RELOH&RXQW\$ODEDPD¥

(VWLPDWLRQRI5HDFWLYLW\RIWKH2UJDQLF&DUERQ

The first step in understanding the reactive 

nature of the organic carbon in Converse Lake and its 

tributaries was to identify the relation between THM 

formation and the presence of organic carbon in the 

water. If TOC and DOC were consistently of a reactive 

nature, a strong, statistically significant relation 

between THM-FP and organic carbon concentrations 

could be expected. The reactive fraction of TOC and 

DOC in the lake and tributaries, however, could vary 

with season or flow; thus, a better indication might be 

the aromatic content of the organic carbon estimated by 

UVA or algal production estimated by chlorophyll. In 

this study, the relation between THM-FP and UVA was 

stronger and statistically more significant than the 

relation between THM-FP and TOC or DOC. 

When water samples were collected for THM-FP 

analyses, concurrent water samples were analyzed for 

potential surrogate concentrations of TOC, DOC, 

UVA-TOC, UVA-DOC, tannin and lignin, and specific 

absorbance, which is a computed value of the UVADOC to DOC ratio. The degree of correlation among 

the potential surrogate concentrations (sampled 

monthly at all sites) and THM-FP (sampled quarterly at 

four sites) was determined by using Spearman rho 

correlation coefficients. This statistical analysis was 

applied to the data to establish the best surrogate for 

THM-FP, which allowed monthly extrapolation of the 

reactive carbon data. The results of the statistical 

correlation indicated statistically significant relations 

between THM-FP and UVA-TOC, UVA-DOC, and 

tannin and lignin (p-value < 0.05; fig. 27), with UVATOC having the strongest correlation (0.7021). 

Therefore, UVA was selected to be the surrogate 

measure of the reactive carbon in a sample. 

AZ

)LJXUH 0HDQWULKDORPHWKDQHFRQFHQWUDWLRQVLQWUHDWHGZDWHUIURPVHOHFWHG

PXQLFLSDOZDWHUVXSSOLHVLQWKH8QLWHG6WDWHV
5HVXOWVRI2UJDQLF&DUERQ$QDO\VLV 

)LJXUH &RUUHODWLRQFRHIILFLHQWVDQGVFDWWHUSORWVRIWULKDORPHWKDQHIRUPDWLRQSRWHQWLDODQGSRWHQWLDOVXUURJDWHFRQFHQWUDWLRQVLQWKH&RQYHUVH

/DNHZDWHUVKHG¥
 $VVHVVPHQWRI:DWHU4XDOLW\&RQGLWLRQVLQWKH-%&RQYHUVH/DNH:DWHUVKHG0RELOH&RXQW\$ODEDPD¥

6SDWLDODQG7HPSRUDO'LVWULEXWLRQ

The degree of spatial and temporal variability of 

TOC, DOC, tannin and lignin, UVA, specific 

absorbance, and THM-FP levels was determined, and 

differences over time and among subbasins were 

assessed. A combination of graphical and statistical 

techniques was used, and GIS coverages were 

developed to better evaluate spatial distribution and 

temporal variability of reactive organic carbon. The 

amount of organic carbon in the water from tributary 

sites varied to some degree from subbasin to subbasin 

and over time during the study period (October 1996 to 

June 1998). In general, the lake sites had intermediate 

organic carbon levels that were more constant spatially 

and temporally than the tributary sites. 

Organic carbon contributions from the tributaries 

to the lake were evaluated. Median DOC and TOC 

concentrations were lowest in Crooked Creek, Long 

Branch, and Hamilton Creek and highest in Boggy 

Branch and Big Creek (appendix 1; figs. 28, 29). The 

greatest range in concentrations in DOC and TOC 

concentrations was observed in Juniper Creek; the 

smallest range in concentrations was observed at the 

lake sites (fig. 28). The dissolved fraction of the 

organic carbon generally accounted for more than 

90 percent of the total organic carbon at all sites. 

Tannin and lignin were used to estimate the 

terrestrial-source component of the organic carbon. 

Median tannin and lignin concentrations displayed a 

similar spatial pattern as the organic carbon, with the 

lowest median value found in Crooked Creek 

(0.5 mg/L) and the highest found in Big Creek 

(1 mg/L) (figs. 28, 29). The greatest interquartile range 

in concentrations in tannin and lignin concentrations 

was identified in Juniper Creek; the least, at the lake 

sites (fig. 28). Tannin and lignin generally accounted 

for about 22 percent of the dissolved organic carbon 

found in water from the tributary sites, and 18 and 

15 percent at the lake sites at the mouth of Crooked 

Creek and at the pump station (sites LCRO and 

LHAM, respectively). 

Median UVA values for water collected at 

tributary sites ranged from 0.165 (Crooked Creek) to 

0.256 cm-1 (Boggy Branch) for unfiltered TOC 

samples (figs. 29, 30), and from 0.122 (Crooked 

Creek) to 0.204 cm-1(Boggy Branch) for filtered, DOC 

samples (fig. 30). Median UVA values at the lake sites 

were intermediate to the range of values for Boggy 

Branch and Crooked Creek, and had less variability. 

Median UVA values for TOC samples at the lake sites 

were 0.168 cm-1 for the mouth of Crooked Creek 

(site LCRO) and 0.158 cm-1 for the pump station at the 

mouth of Hamilton Creek (site LHAM). Median UVA 

values for DOC samples at sites LCRO and LHAM 

were 0.151 and 0.145 cm-1, respectively. The UVA 

values for the DOC samples were normalized for the 

amount of dissolved organic carbon that was present by 

computing the specific ultraviolet absorbance (SUVA). 

Examination of the median SUVA values identified a 

different pattern. The highest median SUVA values 

were at the Crooked (site CRO) and Hamilton 

(site HAM) Creek sites (0.062 and 0.060 cm-1/mg/L, 

respectively); the lowest median SUVA value 

was at the lake site (LHAM) at the pump station 

(0.032 cm-1/mg/L) (fig. 30). This suggests that the 

DOC in Crooked and Hamilton Creeks may be more 

reactive than at the other sites, and that the DOC in the 

lake is less reactive.

Results of the THM-FP analyses identified the 

highest THM-FP concentrations were in water from 
5HVXOWVRI2UJDQLF&DUERQ$QDO\VLV 

)LJXUH %R[SORWVRIWRWDORUJDQLFFDUERQGLVVROYHGRUJDQLFFDUERQDQGWDQQLQDQGOLJQLQFRQFHQWUDWLRQVDWVHOHFWHGVLWHVLQWKH&RQYHUVH

/DNHZDWHUVKHG¥
 $VVHVVPHQWRI:DWHU4XDOLW\&RQGLWLRQVLQWKH-%&RQYHUVH/DNH:DWHUVKHG0RELOH&RXQW\$ODEDPD¥

)LJXUH 5DQJHLQPHGLDQFRQFHQWUDWLRQVRIGLVVROYHGRUJDQLFFDUERQWDQQLQDQGOLJQLQWRWDORUJDQLFFDUERQDQGXOWUDYLROHWDEVRUEDQFH

DWQDQRPHWHUVLQWKH&RQYHUVH/DNHZDWHUVKHG¥
5HVXOWVRI2UJDQLF&DUERQ$QDO\VLV 

)LJXUH %R[SORWVRIXOWUDYLROHWDEVRUEDQFHDWQDQRPHWHUVIRUXQILOWHUHG72&DQGILOWHUHG'2&VDPSOHVDQGVSHFLILFDEVRUEDQFHDW

VHOHFWHGVLWHVLQWKH&RQYHUVH/DNHZDWHUVKHG¥
 $VVHVVPHQWRI:DWHU4XDOLW\&RQGLWLRQVLQWKH-%&RQYHUVH/DNH:DWHUVKHG0RELOH&RXQW\$ODEDPD¥

Big Creek (fig. 31). The median THM-FP 

concentration of five samples was 644 μg/L in Big 

Creek, 322 μg/L in Hamilton Creek, 318 μg/L in the 

lake at the pump station, and 277 μg/L in Crooked 

Creek (appendix 1). The highest THM-FP 

concentrations at all sites were found during or 

immediately after runoff events. 

the Converse Lake study, UVA and SUVA values at the 

lake sites, especially at the pump station, were within 

the same range as those values found in the California 

lakes and rivers. The tributary sites had UVA and SUVA 

values that overlapped the lower range for agricultural 

drains and the upper range for rivers in California. 

THM-FP levels ranged from 239 to 4,526 μg/L in 

agricultural drains in California, and from 144 to 

360 μg/L in rivers and lakes. In the Converse Lake 

study, the levels of THM-FP in Big Creek were within 

the range for agricultural drains in California; the other 

Converse Lake study sites had THM-FP levels that 

overlapped the two ranges. 

The computed land-use percentages from 1992 

MRLC data were correlated with median TOC, UVA, 

and tannin and lignin concentrations for each tributary 

subbasin. The degree of correlation was used to identify 

whether the more reactive organic carbon was related to 

natural (forested) conditions or anthropogenic 

influences in the watershed (fig. 32; table 24). Negative 

correlation coefficients indicated an inverse relation 

between land-use percentages and reactive organic 

carbon (the greater the land-use percentages in a 

subbasin, the less reactive the organic carbon); positive 

coefficients signified a direct relation (the greater the 

land-use percentages, the more reactive the organic 

carbon). Deciduous forests had a statistically significant 

positive correlation (p-value < 0.05) to DOC (0.8829), 

TOC (0.8571), and UVA-TOC (0.8214). Unlike the 

California agricultural drains, the agricultural land-use 

categories of row crop, and pasture and hay showed no 

significant correlation. High-intensity and low-intensity 

residential land-use categories were negatively 

correlated to TOC and DOC but had no significant 

correlation to tannin and lignin or UVA. These findings 

suggest that forested land contributed more reactive 

organic carbon to the watershed than land influenced by 

agricultural and residential activities.

)LJXUH 5DQJHLQWULKDORPHWKDQHIRUPDWLRQSRWHQWLDO

IRUVHOHFWHGWULEXWDU\DQGODNHVLWHVLQWKH&RQYHUVH/DNH

ZDWHUVKHG¥

Previous investigations in California reported 

ranges in UVA from 0.255 to 1.33 cm-1 for agricultural 

drains and from 0.043 and 0.148 cm-1 for lakes and 

rivers (Amy and others, 1990; Krasner and others, 

1994). In these same investigations, SUVA ranged from 

0.038 to 0.060 cm-1/mg/L for agricultural drains and 

from 0.017 to 0.034 cm-1/mg/L for lakes and rivers. In 
5HVXOWVRI2UJDQLF&DUERQ$QDO\VLV 

)LJXUH &RUUHODWLRQEHWZHHQSHUFHQWODQGXVHFDWHJRULHVDQGPHGLDQFRQFHQWUDWLRQVRIWRWDORUJDQLFFDUERQGLVVROYHGRUJDQLFFDUERQ

WDQQLQDQGOLJQLQDQGXOWUDYLROHWDEVRUEDQFHDWQDQRPHWHUVLQWKH&RQYHUVH/DNHZDWHUVKHG¥

7DEOH 6SHDUPDQUKRFRUUHODWLRQFRHIILFLHQWVIRUODQGXVHFDWHJRULHVDQGPHGLDQOHYHOVRIWRWDORUJDQLFFDUERQGLVVROYHGRUJDQLF

FDUERQWDQQLQDQGOLJQLQDQGXOWUDYLROHWDEVRUEDQFHDWQDQRPHWHUVLQWKH&RQYHUVH/DNHZDWHUVKHG

[Coefficients with statistically significant relations are bold (p-value < 0.05). MRLC, multi-resolution land characteristic]

05/&

ODQGXVHFDWHJRU\

7RWDO

RUJDQLF

FDUERQ

'LVVROYHG

RUJDQLF

FDUERQ

7DQQLQ

DQG

OLJQLQ

8OWUDYLROHW

DEVRUEDQFHDW

QDQRPHWHUV

GLVVROYHG

8OWUDYLROHW

DEVRUEDQFHDW

QDQRPHWHUV

WRWDO

Evergreen forest 0.0714 0.1802 0.1684 0.1071 0.1786

Deciduous forest 0.8571 0.8829 0.6924 0.6786 0.8214

Mixed forest 0.5000 0.6307 0.2807 0.3214 0.3571

Transitional 0.6429 0.7388 0.4304 0.2857 0.5000

Row crops -0.4286 -0.5946 -0.2245 -0.3929 -0.4286

Pasture and hay -0.2143 -0.1442 -0.4304 -0.0714 -0.1429

High-intensity residential -0.7783 -0.9163 -0.2912 -0.3336 -0.4077

Low-intensity residential -0.8108 -0.9455 -0.4437 -0.4865 -0.5586

Industrial/commercial/highintensity residential-0.7500 -0.6847 -0.4304 -0.6071 -0.5000

Other grasses -0.5930 -0.6732 -0.3107 -0.5930 -0.5559

Wetlands -0.2143 -0.4000 -0.1123 -0.0714 -0.2857
 $VVHVVPHQWRI:DWHU4XDOLW\&RQGLWLRQVLQWKH-%&RQYHUVH/DNH:DWHUVKHG0RELOH&RXQW\$ODEDPD¥

6RXUFHVRI5HDFWLYH2UJDQLF&DUERQ

Tannin and lignin, derived from the breakdown 

of terrestrial plant material (leaves and crops), can enter 

lakes and streams by runoff or soil flushing during 

storm events or by continual seepage from the soil 

during base-flow periods. These organic compounds 

have a high amount of phenolic groups (more aromatic 

carbon) and, thus, tend to produce by-products during 

chlorination. Decaying organic matter in the lake 

sediment and algal growth also can contribute organic 

carbon. The organic compounds that are derived from 

algae have fewer phenolic groups and, therefore, a 

lower tendency to produce by-products. Manmade 

sources of organic carbon can include human 

wastewater (septic-tank effluent), livestock wastes, and 

cropland. These organic carbon compounds can vary in 

their tendencies to produce by-products.

At the tributary and lake sites, Spearman rho 

correlation coefficients were computed for UVA-TOC, 

UVA-DOC, specific absorbance, streamflow, TOC, 

DOC, tannin and lignin, pH, acid-neutralizing capacity, 

and water temperature (estimate of season) to 

determine the interrelations, if any, among these 

constituents (table 25). At all tributary sites, the 

strongest correlation was between UVA-TOC (selected 

as the best surrogate for trihalomethane-formation 

potential) and tannin and lignin, indicating a terrestrial 

source for the most reactive organic carbon. This 

correlation was statistically significant (p-value < 0.05) 

for Big Creek (1.000), Juniper Creek (0.955), Boggy 

Branch (0.926), Crooked Creek (0.886), and Hamilton 

Creek (0.975). Statistically significant correlations 

(p-value < 0.05) also occurred between tannin and 

lignin and TOC and DOC, respectively, at Juniper 

Creek (0.941, 0.941), Boggy Branch (0.940, 0.926), 

Crooked Creek (0.943, 0.886), and Hamilton Creek 

(0.947, 0.975; table 25), indicating that the major 

source of all organic carbon compounds in these 

streams was terrestrial. No statistically significant 

correlation was found between streamflow and tannin 

and lignin concentrations, UVA-TOC, UVA-DOC, or 

specific absorbance at any of the tributary sites, 

suggesting that the reactive organic carbon reaches the 

streams from the soil and litter zone during both runoff 

and base-flow seepage. 

For the lake sites, Spearman rho correlations 

were used to determine whether the major source of the 

reactive organic carbon in the lake was terrestrial or 

algal in nature. The algal source was estimated by 

chlorophyll a levels, and the terrestrial source was 

estimated by tannin and lignin concentrations. The 

reactive organic carbon was estimated by UVA-TOC, 

which was identified as the best surrogate for THM-FP, 

and UVA-DOC. An extremely strong, positive, 

statistically significant correlation (p-value < 0.01) was 

found between chlorophyll a, TOC, and DOC (1.000; 

table 25), indicating that the major source of organic 

carbon in the lake was algae. The correlations, 

however, between UVA-TOC, UVA-DOC, 

chlorophyll a, TOC, and DOC were not statistically 

significant. UVA-TOC had the strongest correlation 

with tannin and lignin concentrations (0.949), 

indicating a terrestrial source for the most reactive 

organic carbon.

In summary, naturally occurring, terrestrial 

organic carbon compounds from decaying organic 

material such as fallen leaves were the major source of 

reactive organic carbon in the Converse Lake 

watershed. In the lake, algae was considered the major 

source of organic carbon as indicated by strong, 

positive, statistically significant correlations among 

chlorophyll a, TOC, and DOC. The algal-derived 

organic carbon, however, was not considered the major 

source of the reactive organic carbon as indicated by 

the absence of significant statistical correlations among 

chlorophyll a, TOC, DOC, and UVA (the surrogate 

used to represent THM-FP). 
5

HVXOWVRI2UJDQLF&DUERQ$QDO\VLV

7DEOH 6SHDUPDQUKRFRUUHODWLRQPDWUL[IRUVHOHFWHGFRQVWLWXHQWVLQVHYHQWULEXWDU\VLWHVDQGRQHODNHVLWHLQWKH&RQYHUVH/DNHZDWHUVK[ANC, acid-neutralizing capacity; TOC, total organic carbon; DOC, dissolved organic carbon, UVATOC, ultraviolet absorbance of TOC at 254 nanometers; UVat 254 nanometers; —, no data. Values in bold represent statistically significant correlations (p-value < 0.05)]

Big Creek at County Road 63 near Wilmer, 02479945 (site BIG)

&RQVWLWXHQW 6WUHDPIORZ S+ $1& :DWHU WHPSHUDWXUH 7DQQLQ DQG OLJQLQ 72& '2& 89$7

Streamflow 1.000pH -0.447 1.000Acid-neutralizing capacity (ANC) -0.211 0.825 1.000Water temperature 0.300 0.224 0.527 1.000Tannin and lignin 0.500 -0.224 0.158 0.900 1.000Total organic carbon (TOC) 0.100 -0.447 -0.211 0.600 0.800 1.000Dissolved organic carbon (DOC) 0.100 -0.447 -0.211 0.600 0.800 1.00 1.000UVA-254TOC 0.500 -0.224 0.158 0.900 1.00 0.800 0.800 1.00UVA-254 DOC 0.800 -0.224 0.158 0.800 0.900 0.500 0.500 0.9Specific absorbance 0.300 0.224 0.000 -0.500 -0.600 -0.900 -0.900 -0.6

Juniper Creek at Glenwood Road near Fairview, 02479948 (site JUN)

&RQVWLWXHQW 6WUHDPIORZ S+ $1& :DWHU WHPSHUDWXUH 7DQQLQ DQG OLJQLQ 72& '2& 89$7

Streamflow 1.000pH 0.572 1.000Acid-neutralizing capacity (ANC) -0.319 0.086 1.000Water temperature -0.725 -0.235 0.235 1.000Tannin and lignin 0.334 0.154 -0.770 -.137 1.000Total organic carbon (TOC) 0.086 0.058 -0.812 0.232 0.941 1.000Dissolved organic carbon (DOC) 0.086 0.058 -0.812 0.232 0.941 1.000 1.000UVA-254TOC 0.465 0.279 -0.588 -0.147 0.955 0.812 0.812 1.0UVA-254 DOC 0.371 0.319 -0.522 0.232 0.941 0.829 0.829 0.9Specific absorbance -0.143 0.406 -0.841 0.203 -0.638 -0.714 -0.714 -0.4


$VVHVVPHQWRI:DWHU4XDOLW\&RQGLWLRQVLQWKH-%&RQYHUVH/DNH:DWHUVKHG0RELOH&RXQW\$ODEDPD¥

7DEOH 6SHDUPDQUKRFRUUHODWLRQPDWUL[IRUVHOHFWHGFRQVWLWXHQWVLQVHOHFWHGVLWHV&RQYHUVH/DNHZDWHUVKHG¦&RQWLQXHG[ANC, acid-neutralizing capacity; TOC, total organic carbon; DOC, dissolved organic carbon, UVATOC, ultraviolet absorbance of TOC at 254 nanometers; UVA

254 nanometers; —, no data. Values in bold represent statistically significant correlations (p-value < 0.05)]

Collins Creek at Glenwood Road near Fairview, 02479950 (site COL)

&RQVWLWXHQW 6WUHDPIORZ S+ $1& :DWHU WHPSHUDWXUH 7DQQLQ DQG OLJQLQ 72& '2& 89$72& 

Streamflow 1.000pH -0.058 1.000Acid-neutralizing capacity (ANC) 0.412 0.806 1.000Water temperature -0.638 -0.074 -0.254 1.000Tannin and lignin 0.464 -0.470 -0.119 0.279 1.000Total organic carbon (TOC) 0.086 -0.812 -0.706 0.377 0.754 1.000Dissolved organic carbon (DOC) -0.086 -0.812 -0.706 0.522 0.754 0.943 1.000UVA-254TOC 0.200 0.260 0.412 0.406 0.667 0.143 0.257 1.000UVA-254 DOC 0.371 0.319 0.618 0.232 0.667 -0.029 0.086 0.943 Specific absorbance — — — — — —— — 

Long Branch near Wilmer, 02479955 (site LON)

&RQVWLWXHQW 6WUHDPIORZ S+ $1& :DWHU WHPSHUDWXUH 7DQQLQ DQG OLJQLQ 72& '2& 89$72& 

Streamflow 1.000pH -0.105 1.000Acid-neutralizing capacity (ANC) -0.632 0.833 1.000Water temperature -0.400 -0.211 -0.316 1.000Tannin and lignin 0.258 0.272 0 0.775 1.000Total organic carbon (TOC) 0 -0.316 -0.316 0.800 0.774 1.000Dissolved organic carbon (DOC) 0 -0.316 -0.316 0.800 0.775 1.000 1.000UVA-254TOC -0.200 0.738 0.632 0.800 0.774 0.400 0.400 1.000UVA-254 DOC -0.400 0.211 0.316 1.000 0.774 0.800 0.800 0.769 Specific absorbance — — — — — — — — 
5

HVXOWVRI2UJDQLF&DUERQ$QDO\VLV

7DEOH 6SHDUPDQUKRFRUUHODWLRQPDWUL[IRUVHOHFWHGFRQVWLWXHQWVLQVHOHFWHGVLWHV&RQYHUVH/DNHZDWHUVKHG¦&RQWLQXHG[ANC, acid-neutralizing capacity; TOC, total organic carbon; DOC, dissolved organic carbon, UVATOC, ultraviolet absorbance of TOC at 254 nanometers; UVA

254 nanometers; —, no data. Values in bold represent statistically significant correlations (p-value < 0.05)]

Boggy Branch near Wilmer, 02479960 (site BOG)

&RQVWLWXHQW 6WUHDPIORZ S+ $1& :DWHU WHPSHUDWXUH 7DQQLQ DQG OLJQLQ 72& '2& 89$72& 

Streamflow 1.000pH -0.377 1.000Acid-neutralizing capacity (ANC) -0.882 0.667 1.000Water temperature -0.348 -0.143 0.058 1.000Tannin and lignin 0.250 -0.772 -0.548 0.648 1.000Total organic carbon (TOC) 0.500 -0.841 -0.750 0.377 0.940 1.000Dissolved organic carbon (DOC) 0.522 -0.771 -0.783 0.423 0.926 0.986 1.000UVA-254TOC 0.203 -0.486 -0.406 0.771 0.926 0.812 0.829 1.000UVA-254 DOC 0.377 -0.145 -0.319 0.543 0.617 0.522 0.543 0.829 Specific absorbance -0.116 0.657 0.493 -0.314 -0.679 -0.754 -0.771 -0.486 

Crooked Creek near Fairview, 02479980 (site CRO)

&RQVWLWXHQW 6WUHDPIORZ S+ $1& :DWHU WHPSHUDWXUH 7DQQLQ DQG OLJQLQ 72& '2& 89$72& 

Streamflow 1.000pH 0.145 1.000Acid-neutralizing capacity (ANC) 0.334 0.616 1.000Water temperature -0.314 -0.058 0.516 1.000Tannin and lignin 0.486 -0.290 0.455 0.543 1.000Total organic carbon (TOC) 0.429 -0.493 0.152 0.429 0.943 1.000Dissolved organic carbon (DOC) 0.371 -0.667 0.030 0.314 0.886 0.943 1.000UVA-254TOC 0.429 0.029 0.759 0.714 0.886 0.714 0.600 1.000UVA-254 DOC 0.543 0.116 0.0820 0.543 0.771 0.543 0.486 0.943 Specific absorbance -0.200 0.522 0.152 -0.086 -0.657 -0.771 -0.829 -0.257 


$VVHVVPHQWRI:DWHU4XDOLW\&RQGLWLRQVLQWKH-%&RQYHUVH/DNH:DWHUVKHG0RELOH&RXQW\$ODEDPD¥

7DEOH 6SHDUPDQUKRFRUUHODWLRQPDWUL[IRUVHOHFWHGFRQVWLWXHQWVLQVHOHFWHGVLWHV&RQYHUVH/DNHZDWHUVKHG¦&RQWLQXHG[ANC, acid-neutralizing capacity; TOC, total organic carbon; DOC, dissolved organic carbon, UVATOC, ultraviolet absorbance of TOC at 254 nanometers; UVA

254 nanometers; —, no data. Values in bold represent statistically significant correlations (p-value < 0.05)]

Hamilton Creek at Snow Road near Semmes, 02480002 (site HAM)

&RQVWLWXHQW 6WUHDPIORZ S+ $1& :DWHU WHPSHUDWXUH 7DQQLQ DQG OLJQLQ 72& '2& 89$72& 

Streamflow 1.000pH 0.433 1.000Acid-neutralizing capacity (ANC) -0.526 0.406 1.000Water temperature -0.667 0.211 0.975 1.000Tannin and lignin -0.553 -0.351 0.237 0.410 1.000Total organic carbon (TOC) -0.395 -0.054 0.289 0.410 0.947 1.000Dissolved organic carbon (DOC) -0.462 -0.158 0.359 0.500 0.975 0.975 1.000UVA-254TOC -0.462 -0.158 0.359 0.500 0.975 0.975 1.00 1.000UVA-254 DOC -0.403 0.264 0.359 0.400 0.667 0.821 0.700 0.700 Specific absorbance 0.616 0.527 -0.103 -0.300 -0.975 -0.872 -0.900 -0.900 

Hamilton Creek (Big Creek Lake intake) near Semmes, 02480004 (site LHAM

&RQVWLWXHQW &KORURSK\OOD S+ $1& :DWHU WHPSHUDWXUH 7DQQLQ DQG OLJQLQ 72& '2& 89$72& 

Chlorophyll a 1.000pH -1.000 1.000Acid-neutralizing capacity (ANC) -0.258 0.258 1.000Water temperature 0.400 -0.400 0.775 1.000Tannin and lignin -0.316 0.316 0.574 0.211 1.000Total organic carbon (TOC) 1.000 -1.00 -0.258 0.400 -0.316 1.000Dissolved organic carbon (DOC) 1.000 -1.00 -0.258 0.400 -0.316 1.000 1.000UVA-254TOC -0.400 0.400 0.775 0.400 0.949 -0.400 -0.400 1.000UVA-254 DOC -0.400 0.400 0.775 0.400 0.949 -0.400 -0.400 0.800 Specific absorbance -0.800 0.800 0.775 0.200 0.632 -0.800 -0.800 -0.400 
6XPPDU\DQG&RQFOXVLRQV 

6800$5<$1'&21&/86,216

J.B. Converse (Converse) Lake is a 3,600-acre, 

tributary-storage reservoir in southwestern Alabama. 

The 103-mi2

 watershed is located in Mobile County 

west of the city of Mobile near the AlabamaMississippi State line. The lake is designated for 

aquatic-life and public-water supply use by the ADEM. 

The climate in the Converse Lake watershed is 

subtropical. The mean annual precipitation for the 

Mobile area is 64 in.; the mean annual temperature is 

67.5 °F. The study area lies within a single district of 

the Coastal Plain Physiographic Province—the 

Southern Pine Hills District of the East Gulf Coastal 

Plain Physiographic section. Two geologic units of 

Tertiary age, the Miocene Series undifferentiated and 

the Citronelle Formation of Pliocene age, underlie the 

watershed and consist of semiconsolidated to 

unconsolidated sand, silt, gravel, and clay. These units 

dip and thicken to the southwest.

Converse Lake receives inflow from seven major 

tributaries that drain about three-fourths of the total 

watershed; three of the tributaries are monitored by 

streamflow gages. Big Creek, Crooked Creek, and 

Hamilton Creek had mean annual streamflows of 72.2, 

19.4, and 25.0 ft3

/s, respectively, for the period 1990 to 

1998. Hamilton Creek subbasin had the greatest 

streamflow yield of 3.04 (ft3

/s)/mi2; Crooked and Big 

Creeks had yields of 2.40 and 2.29 (ft3/s)/mi2, 

respectively. Hamilton Creek had better sustained 

flows and contributed increasingly greater percentages 

of the total inflow to the lake during low-flow periods, 

until it equaled or slightly exceeded the streamflow 

yield at Big Creek. 

The Converse Lake watershed is forested and 

rural. Forests cover over 64 percent of the watershed; 

agricultural use accounts for about 31 percent of the 

watershed. Residential and commercial development 

account for only 1 percent of the total land use in the 

watershed. The Big Creek subbasin is covered by 

forested land with some agricultural land. The Crooked 

Creek subbasin has the greatest percentage of 

agricultural land use (42 percent) in the watershed, 

consisting mostly of plant nurseries. The percentage of 

residential area (3.4 percent) in the Crooked Creek 

subbasin is second only to the amount of residential 

land use in the Hamilton Creek subbasin (3.9 percent). 

Point sources in the watershed consist of two 

hazardous- and solid-waste sites and two permitted 

compliance system sites; no waste or by-product 

releases (to air, water, or ground water) were reported 

during the study period. 

Waters in Converse Lake and its tributaries have 

low pH and low specific conductance values, which is 

typical of waters in humid climates that drain highly 

resistant sands and gravels. Although all sites in the 

Converse Lake watershed had pH levels that 

periodically fell below the ADEM criterion of 6, Big 

Creek and Boggy Branch had median pH values of 5.6 

and 5.9, respectively. Statistical correlations indicated 

that the greater the amount of commercial, industrial, 

and residential development (human influences), the 

greater the tendency for the streamwater to have a more 

neutral median pH and a greater capacity to neutralize 

acid. This correlation, in conjunction with the 

environmental factors of resistant rock types and acidic 

soil in the watershed, provide a strong indication that 

low pH and low ANCs are natural in origin, and not 

anthropogenic. The median specific conductance 

ranged from 23 (Collins Creek) to 43 μS/cm (Long 

Branch) for the study period. 

All tributary sites in the Converse Lake 

watershed had minimum dissolved-oxygen 

concentrations above the ADEM criteria of 5 mg/L 

except for Boggy Branch, which had a minimum 

dissolved-oxygen concentration of 3.7 mg/L. Median 

dissolved-oxygen concentrations ranged from 6.9 

(Boggy Branch) to 8.6 mg/L (Juniper Creek and Long 

Branch) for the study period. Converse Lake becomes 

stratified during August and September when 

dissolved-oxygen levels typically fall below 1 mg/L at 

depths greater than 20 ft. 

No substantial differences were observed in 

water chemistry among tributary sites. Big Creek had a 

relatively high nitrate component, especially during 

base-flow periods, suggesting a ground-water source. 

Increases in calcium and bicarbonate concentrations in 

Crooked Creek and Hamilton Creek during high 

streamflow periods suggested a runoff or soil-zone 

flushing source. Converse Lake and its tributaries had 

median total iron concentrations that exceeded the 

ADEM secondary standard for drinking water of 

300 μg/L; only Boggy Branch had median total 

manganese concentrations that exceeded the secondary 

standard of 50 μg/L.

Total nitrogen (with the exception of Long 

Branch), total Kjeldahl nitrogen (with the exception of 

Hamilton Creek), total organic nitrogen (with the 

exception of Boggy Branch), ammonia (with the 

exception of Long Branch), total inorganic nitrogen, 
 $VVHVVPHQWRI:DWHU4XDOLW\&RQGLWLRQVLQWKH-%&RQYHUVH/DNH:DWHUVKHG0RELOH&RXQW\$ODEDPD¥

and total phosphorus (with the exception of Long and 

Boggy Branches) exhibited a significant, positive 

relation with streamflow, which indicates the dominant 

source of nutrient input to the watershed is from 

nonpoint sources. 

In comparison to published values, the computed 

total phosphorus yields for Big Creek, Collins Creek, 

Long Branch, and Boggy Branch were within the 

expected range of forested land that had minor 

agriculture (pasture, crops, mixed agriculture). Total 

phosphorus yields were higher in the Crooked and 

Hamilton Creek subbasins (0.52 and 0.40 (kg/ha)/yr, 

respectively) compared to the other tributary subbasins, 

probably as a result of higher percentages of residential 

and nonrow crop (plant nurseries) land use in these 

subbasins. Juniper Creek subbasin had a similar total 

phosphorus yield of 0.45 (kg/ha)/yr present but little to 

no residential influence. The total nitrogen yields at the 

tributary sites also fell within the published ranges for 

forest, agriculture (pasture, nonrow crops), and urban 

land uses. 

For the 1991 water year, the total phosphorus 

yields ranged from 0.10 (Long Branch) to 

0.52 (kg/ha)/yr (Crooked Creek); total nitrogen yields 

ranged from 3.83 (Collins Creek) to 8.45 (kg/ha)/yr 

(Big Creek). The nutrient loads at Big Creek, Crooked 

Creek, and Hamilton Creek accounted for over 

70 percent of the total load in the watershed. Big Creek 

had the highest nutrient loads, accounting for almost 

60 percent of the total nitrogen and total Kjeldahl 

nitrogen, 47 percent of the total inorganic nitrogen, and 

36 percent of total phosphorus loads. Crooked and 

Juniper Creeks each contributed 21 percent of the total 

phosphorus load in 1991; Hamilton Creek contributed 

about 16 percent of the total phosphorus load. Total 

phosphorus yields from Crooked, Juniper, and 

Hamilton Creek subbasins were 2 to 5 times those of 

the other tributary subbasins.

During the study period, annual nutrient loads 

and yields were highest for the 1991 and 1998 water 

years and lowest for the 1992 and 1994 water years 

(with the exception of total inorganic nitrogen in 1995). 

A combined mean annual load of 75,400 kg of total 

nitrogen, 36,950 kg of total Kjeldahl nitrogen, 

28,870 kg of total inorganic nitrogen, and 3,480 kg of 

total phosphorus were contributed to the lake by Big 

Creek, Hamilton Creek, and Crooked Creek. Of the 

combined loads, 62 percent of the total nitrogen, 

81 percent of the total Kjeldahl nitrogen, 54 percent of 

the total inorganic nitrogen, and 47 percent of the total 

phosphorus originated from the forested subbasin of 

Big Creek. The more residential and agricultural 

subbasins of Crooked Creek and Hamilton Creek, 

however, yielded over twice the total phosphorus per 

hectare of land use. Crooked and Hamilton Creek 

subbasins also had higher total inorganic nitrogen 

yields. The mean annual nutrient yields were averaged 

to obtain a watershed yield for each nutrient 

species—0.0933 (kg/ha)/yr of orthophosphate, 

0.358 (kg/ha)/yr of total phosphorus, 2.72 (kg/ha)/yr of 

total inorganic nitrogen, 0.0035 (kg/ha)/yr of total 

ammonia, 3.20 (kg/ha)/yr of total Kjeldahl nitrogen, 

and 6.46 (kg/ha)/yr of total nitrogen. 

The trend analysis detected little or no change in 

nutrient concentrations at the tributary and lake sites in 

the Converse Lake watershed for the 1991 to 1998 

water years. A complex relation seemed to exist 

between annual nutrient contributions to Converse 

Lake from the tributaries, and the lake’s ability to 

assimilate these contributions by biomass uptake, 

sedimentation, and outflow. The lack-of-fit of the 

estimated in-lake phosphorus concentration from a 

simple input-output empirical model to the observed 

value in Converse Lake accentuated the need for a more 

robust model of lake water quality and trophic 

response. 

Monitoring in the Converse Lake watershed 

showed that some tributaries to the lake had fecal 

bacterial concentrations that were above the ADEM 

criteria for whole-body contact uses. Bacterial 

concentrations at lake sites at the mouth of Crooked 

Creek and Hamilton Creek at the pump station were 

well below ADEM criteria levels. Elevated bacterial 

concentrations in the tributaries did not appear to cause 

elevated levels in the lake.

Juniper Creek had the highest geometric mean 

concentrations for all bacteria types during the study. 

Trend analysis indicated that flow-adjusted fecal 

streptococcus concentrations increased at Juniper 

Creek during the 8 years of data collection. The 

increasing trend in bacteria is cause for concern 

because the median fecal bacteria levels in Juniper 

Creek for 1990–98 were above the ADEM whole-body 

criteria levels.

There were few detections of Giardia and 

Cryptosporidium at sites in the lake and in the rawwater intake during the monitoring effort. The low 

number of detections made it difficult to arrive at any 

conclusions about actual cyst concentrations in the 

water supply. Most of the detections occurred during 
6HOHFWHG5HIHUHQFHV 

the summer, but so few cysts were detected that it is not 

clear if there is a seasonal influence on cyst density. 

In the Converse Lake watershed, naturally 

occurring, terrestrial organic carbon compounds 

derived from decaying organic material, such as fallen 

leaves, were the major source of reactive organic 

carbon, which tends to form trihalomethanes in the 

presence of chlorine. In the lake, algae was considered 

the major source of organic carbon as indicated by 

strong, positive, statistically significant correlations 

among chlorophyll a, TOC, and DOC. The algalderived organic carbon, however, was not considered a 

major source of the reactive organic carbon as indicated 

by the absence of significant statistical correlations 

between chlorophyll a, TOC, DOC, and UVA (the 

surrogate used to represent THM-FP). 

In conclusion, water quality in Converse Lake 

and its tributaries meets the criteria mandated by the 

ADEM and the Clean Water Act, which require that all 

waters be “fishable and swimmable.” The exceptions 

include natural acidic pH levels, iron and manganese 

levels above secondary or aesthetic criteria, and fecal 

bacterial levels in some tributaries above “swimmable” 

criteria. Water-management concerns also include 

potential sources of reactive organic carbon that form 

trihalomethanes when raw water is chlorinated, and 

excessive nutrient loads to the lake that can produce 

borderline mesotrophic/eutrophic conditions.

Results of this study have long-range watershed 

management implications. Though the low pH levels 

seem to be naturally occurring, future changes in land 

use could lower pH levels even more, especially since 

the soils have very little acid-neutralizing capacity. 

Identification of fecal bacterial sources, and 

implementation and evaluation of best-management 

practices, may be considered to prevent bacterial 

contamination in the lake. The major source of reactive 

organic carbon was determined to be from the decay of 

plant material from land rather than from in-lake algal 

production. The trophic state of the lake seems to be 

moving toward a more eutrophic state; however, the 

changes are not fully explained by nutrient 

contributions from the tributaries to the lake. A better 

understanding of the major factors affecting the trophic 

state of the lake is needed.

6(/(&7('5()(5(1&(6

Aiken, G.R., and Cotsaris, E., 1995, Soil and 

hydrology—Their effect on NOM: Journal of the 

American Water Works Association, p. 36–45. 

Alabama Department of Environmental Management, 

1994a, Water quality criteria: Alabama Department of 

Environmental Management Administrative Code, 

chap. 335–6–10.

——— 1994b, Water use classifications for interstate and 

intrastate waters: Alabama Department of 

Environmental Management Administrative Code, 

chap. 335–6–11, 47 p.

——— 1996, 305(b) Water-quality report to Congress 

for calendar years 1994 and 1995: Montgomery, 

Alabama Department of Environmental Management, 

278 p.

——— 1999, 305(b) Water-quality report to Congress for 

calendar years 1997 and 1998: Montgomery, Alabama 

Department of Environmental Management, Part III-7, 

Section G, 320 p.

——— 2000, Water quality criteria: Alabama Department of 

Environmental Management Administrative Code, 

chaps. 335–6–10 and 335–6–11.

Amy, G.L., Thompson, J.M., Tan, L., Davis, M.K., and 

Krasner, S.W., 1990, Evaluation of THM precursors 

from agricultural drains: Journal of American Water 

Works Association, v. 82, no. 1, p. 57–64.

Amy, G.L., Wilson, L.G., Conroy, A., Chahbandour, J., 

Zhai, W., and Siddiqui, M., 1993, Fate of chlorination 

byproducts and nitrogen species during effluent 

recharge and soil aquifer treatment (SAT): Water 

Environment Research, v. 65, no. 6, p. 726–734.

Atkins, J.B., and Pearman, J.L., 1994, Low-flow and flowduration characteristics of Alabama streams: U.S. 

Geological Survey Water-Resources Investigations 

Report 93–4186, 264 p.

Barber, L.B., II, Brown, G.K., Kennedy, K.R., Leenheer, 

J.A., Noyes, T.I., Rostad, C.E., Thorn, K.A., 1997, 

in Kendall, D.R., ed., Proceedings of the American 

Water Resources Association Symposium, Conjunctive 

use of water resources, aquifer storage and recovery: 

October 19–23, 1997, Long Beach, Calif., 

p. 261–272. 

Bayne, D.R., Seesock, W.C., and Reutebuch, E.M., 1998, 

Limnological study of Big Creek Lake: Department of 

Fisheries and Allied Aquaculture, Alabama 

Agricultural Experiment Station, Auburn University, 

74 p.

Bradu, D., and Mundlak, Y., 1970, Estimation in lognormal 

linear models: Journal of the American Statistical 

Association, v. 65, no. 329, p. 198–211.

Carlson, R.E., 1977, A trophic state index for lakes: 

Limnology and Oceanography, v. 22, no. 2, 

p. 361–369.
 $VVHVVPHQWRI:DWHU4XDOLW\&RQGLWLRQVLQWKH-%&RQYHUVH/DNH:DWHUVKHG0RELOH&RXQW\$ODEDPD¥

Chapra, S.C., 1975, Comment on “An empirical method of 

estimating retention of phosphorus in lakes” by 

W.B. Kirchner and P.J. Dillon: Water Resources 

Research, v. 11, p. 1033–1034.

Cohn, T.A., 1988, Adjusted maximum likelihood estimation 

of the moments of lognormal populations from type 1 

censored samples: U.S. Geological Survey Open-File 

Report 88–350, 34 p.

Cohn, T.A., Caulder, D.L., Gilroy, E.J., Zynjuk, L.D., and 

Summers, R.M., 1992, The validity of a simple 

statistical model for estimating fluvial constituent 

loads—An empirical study involving nutrient loads 

entering Chesapeake Bay: Water Resources Research, 

v. 28, no. 5, p. 937–942.

Cohn, T.A., DeLong, L.L., Gilroy, E.J., Hirsch, R.M., and 

Wells, D.K., 1989, Estimating constituent loads: Water 

Resources Research, v. 25, no. 5, p. 937–942.

Conrad, Laura, 1998, The tedious hunt for Cryptosporidium: 

Today’s Chemist at Work, American Chemical Society, 

March 1998, p. 24–28.

Davis, M.E., 1987, Stratigraphic and hydrogeologic 

framework of the Alabama Coastal Plain: U.S. 

Geological Survey Water-Resources Investigations 

Report 87–4112, 39 p., + 17 pls.

de Leer, E.W., and Erkelens, C., 1989, Pathways for the 

production of organochlorine compounds in the 

chlorination of humic materials, in Larson, R.A., ed., 

Biohazards of drinking water treatment: Boca Raton, 

Fla., Lewis Publishers, p. 97–106.

Dillon, P.J., and Kirchner, W.B., 1975, Reply to Chapra’s 

comment on “An empirical method of estimating 

retention of phosphorus in lakes” by W.B. Kirchner 

and P.J. Dillon: Water Resources Research, v. 11, 

p. 1035–1036.

Drever, J.I., 1988, The geochemistry of natural waters: 

Englewood Cliffs, N.J., Prentice Hall, Inc., 437 p.

Dufour, A.P., 1977, Escherichia coli—the fecal coliform, in

Hoadley, A., and Dutka, B.J., eds., Bacterial 

indicators/health hazards associated with water, 1977: 

American Society for Testing and Materials, ASTM 

STP 635, p. 222–238.

Edminston, H.L., and Myers, V.B., 1984, Florida lakes 

assessment—Combining macrophyte, chlorophyll, 

nutrient, and public benefit parameters into a 

meaningful lake management scheme—Lake and 

Reservoir Management, Proceedings of the Third 

Annual Conference of the North American Lake 

Management Society: October 18–20, 1993, 

Knoxville, Tenn., U.S. Environmental Protection 

Agency 440.5/84–001, p. 25–39.

Gakstatter, J.H., Allum, M.O., and Omernik, J.M., 1975, 

Lake eutrophication—Results from the National 

Eutrophication Survey: United States Environmental 

Protection Agency, Corvallis, Oreg., Corvallis 

Environmental Research Lab, 32 p.

Gilroy, E.J., Hirsch, R.M., and Cohn, T.A., 1990, Mean 

square error of regression-based constituent transport 

estimates: Water Resources Research, v. 26, no. 9, 

p. 2069–2077.

Greenberg, A.E., Clesceri, L.S., Eaton, A.D., and Franson, 

M.H., eds., 1992a, Part 5710B, Trihalomethane 

formation potential (TFP)—Standard methods 

for the examination of water and wastewater 

[18th ed.]: Washington, D.C., American Public 

Health Association, American Water Works 

Association, and the Water Environment Federation, 

p. 5-45–5-48.

——— 1992b, Part 9711B, Giardia lamblia—Standard 

methods for the examination of water and 

wastewater [18th ed.]: Washington, D.C., 

p. 9-124–9-128.

Hajek, B.F., Gilbert, F.L.,and Steers, C.A., 1975, Soil 

associations of Alabama: Auburn, Ala., U.S. 

Department of Agriculture, Agricultural Experimental 

Station, Agronomy and Soils Department, Series 

No. 24, 30 p.

Helsel, D.R., 1987, Advantages of nonparametric procedures 

for analysis of water quality data: Hydrological 

Sciences, v. 32, p. 179–190.

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

water resources: New York, Elsevier, 522 p.

Hem, J.D., 1985, Study and interpretation of the chemical 

characteristics of natural water: U.S. Geological Survey 

Water-Supply Paper 2254, 263 p.

Hibler, C.P., and Hancock, C.M., 1990, Waterborne 

giardiasis, in McFeters, G.A., ed., Drinking water 

microbiology—Progress and recent developments: 

New York, Springer-Verlag, p. 271–290.

Hirsch, R.M., Slack, J.R., and Smith, R.A., 1982, Techniques 

of trend analysis for monthly water quality data: Water 

Resources Research, v. 20, p. 727–732.

Journey, C.A., Psinakis, W.L., and Atkins, J.B., 1995, 

Streamflow in and water quality and bottom material 

analyses of the J.B. Converse Lake Basin, Mobile 

County, Alabama, 1990–1992: U.S. Geological Survey 

Water-Resources Investigations Report 95–4106, 

69 p.

Kirchner, W.B., and Dillon, P.J., 1975, An empirical method 

of estimating the retention of phosphorus in lakes: 

Water Resources Research, v. 11, p. 182–183.

Korshin, G.V., Li, C., and Benjamin, M.M., 1997, 

Monitoring the properties of natural organic matter 

through UV spectroscopy—A consistent theory: Water 

Research, v. 31, no. 7, p. 1787–1795.

Krasner, S.W., Sclimenti, M.J., and Means, E.G., 1994, 

Quality degradation—Implications for DBP formation: 

Journal of American Water Works Association, v. 70, 

p. 653–660.
6HOHFWHG5HIHUHQFHV 

Larsen, D.P., and Mercier, H.T., 1976, Phosphorus retention 

capacity of lakes: Journal of the Fisheries Research 

Board of Canada, v. 33, p. 1742–1750.

Larson, R.A., and Weber, E.J., 1994, Reaction mechanisms 

in environmental organic chemistry: Boca Raton, Fla., 

Lewis Publishers.

Likens, G.E., and Bormann, F.H., 1995, Biogeochemistry of 

a forested ecosystem, (2d ed.): New York, SpringerVerlag, 159 p.

Miller, R.E., Randtke, S.J., Hathaway, L.R., and Denne, J.E., 

1990, Organic carbon and THM formation potential in 

Kansas groundwaters: Journal of American Water 

Works Association, v. 82, p. 49–62. 

Mooty, W.S., 1988, Geohydrology and susceptibility of 

major aquifers to surface contamination in Alabama; 

Area 13: U.S. Geological Survey Water-Resources 

Investigations Report 88–4080, 29 p.

Myers, D.N., and Wilde, F.D., eds., 1999, Biological 

indicators—National field manual for the collection 

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

Techniques of Water-Resources Investigations, 

book 9, chap. A7.

National Oceanic and Atmospheric Administration, 

National Climate Data Center, 1998, U.S. monthly 

precipitation for cooperative and National Weather 

Service sites: accessed September 1, 1998, at URL 

http://www.ncdc.noaa.gov/ol/climate/online/

coop-precip.html for Mobile Regional Airport 

station 015478.

Nieminski, E.C., Chaudhuri, S., and Lamoreaux, T.J., 1993, 

The occurrence of DBPs in Utah drinking waters: 

Journal of the American Water Works Association, 

v. 85, p. 98–105. 

Pearman, J.L., Sedberry, F.C., Stricklin, V.E., and Cole, P.W., 

1991, Water resources data, Alabama, water year 1991: 

U.S. Geological Survey Water-Data Report AL–91–1, 

475 p.

——— 1992, Water resources data, Alabama, water year 

1992: U.S. Geological Survey Water-Data Report 

AL–92–1, 457 p.

Pearman, J.L., Stricklin, V.E., and Psinakis, W.L., 1998, 

Water resources data, Alabama, water year 1998: U.S. 

Geological Survey Water-Data Report AL–98–1, 444 p.

Porcella, D.B., Peterson, S.A., and Larsen, D.P., 1980, Index 

to evaluate lake restoration: Proceedings of the 

American Society of Civil Engineers, Journal of the 

Environmental Engineering Division, v. 106, 

p. 1151–1169.

Rast, W., and Lee, G.F., 1978, Summary analysis of the 

North American Project (U.S. portion) OECD 

Eutrophication Project—Nutrient loading-lake 

response relationships and trophic stat indices: U.S. 

Environmental Protection Agency, Corvallis, Oreg., 

Corvallis Environmental Research Laboratory, Report 

EPA–600/3–78–008, 455 p.

Rathbun, R.E., 1996, Disinfection by-product yields from 

the chlorination of natural waters: Archives of 

Environmental Contamination and Toxicology, v. 31, 

no. 3, p. 420–425.

Reckhow, D.A., Singer, P.C., and Malcolm, R.L., 

1990, Chlorination of humic materials—Byproduct 

formation and chemical interpretations: Journal 

of American Water Works Association, v. 24, 

p. 1655–1664.

Reckhow, K.H., 1979, Empirical lake models for 

phosphorus—Development, applications, 

uncertainty, in Scavia, D., and Robertson, A., 

eds., Perspectives on lake ecosystems modeling: 

Ann Arbor, Mich., Ann Arbor Science, 

p. 193–222.

Reckhow, K.H., Beaulac, M.N., and Simpson, J.T., 1980, 

Modeling phosphorus loading and lake response under 

uncertainty—A manual and compilation of export 

coefficients: U.S. Environmental Protection Agency, 

Office of Water Regulations and Standards, EPA 440/5–

80–011, 214 p.

Reckhow, K.H., and Clements, J.T., 1984, A cross-sectional 

model for phosphorus in southeastern U.S. lakes—Lake 

and reservoir management, Proceedings of the Third 

Annual Conference of the North American Lake 

Management Society: October 18–20, 1993, Knoxville, 

Tenn., U.S. Environmental Protection Agency 

440.5/84–001, p. 186–192.

Reed, P.C., 1971, Geology of Mobile County, Alabama: 

Tuscaloosa, Geological Survey of Alabama, Map 93, 

8 p.

Reed, P.C., and McCain, J.F., 1972, Water availability in 

Mobile County, Alabama: Tuscaloosa, Geological 

Survey of Alabama, Map 121, 45 p.

Reutebuch, E.M., Bayne, D.R., and Seesock, W.C., 1997, 

Land use/land cover changes in the Big Creek 

watershed derived from Landsat TM data—1984–1995: 

Auburn, Ala., Auburn University, 16 p.

Rook, J.J., 1977, Chlorination reactions of fulvic acids in 

natural waters: Environmental Science and Technology, 

v. 11, p. 478–482. 

Rose, J.B., 1990, Occurrence and control of 

Cryptosporidium in drinking water, Chapter 14, in

McFeters, G.A., ed., Drinking water 

microbiology—Progress and recent developments: 

New York, Springer-Verlag, p. 294–321.

Sapp, D.C., and Emplaincourt, J., 1975, Physiographic 

regions of Alabama: Geological Survey of Alabama, 

Map 168, 1 sheet.

Searcy, J.K., 1959, Flow-duration curves: U.S. Geological 

Survey Water-Supply Paper 1542–A, 33 p.

Silverstein, R.M., Bassler, G.C., Morrill, T.C., 1991, 

Spectrometric identification of organic compounds 

(5th ed.): New York, John Wiley & Sons, Inc., 

419 p. 
 $VVHVVPHQWRI:DWHU4XDOLW\&RQGLWLRQVLQWKH-%&RQYHUVH/DNH:DWHUVKHG0RELOH&RXQW\$ODEDPD¥

Singer, P.C., Obolensky, A., and Grenier, A.J., 1995, DBPs 

in chlorinated North Carolina drinking waters: Journal 

of the American Water Works Association, v. 87, 

no. 10, p. 83–102. 

Snoeyink, V.L., and Jenkins, D., 1980, Water chemistry: 

New York, John Wiley & Sons, Inc., 463 p.

Stumm, W., and Morgan, J.J., 1996, Aquatic 

chemistry—Chemical equilibria and rates in natural 

waters (3d ed.): New York, John Wiley & Sons, Inc., 

1022 p.

Summers, R.S., Hooper, S.M., Shukairy, H.M., Solarik, G., 

and Owen, D. J., 1996, Assessing DBP yield—Uniform 

formation conditions: Journal of the American Water 

Works Association, v. 88, no. 6, p. 80–93.

Symons, J.M., Stevens, A.A., Clark, R.M., Geldreich, E.E., 

Love, O.T., Jr., and DeMarco, J., 1981, Treatment 

techniques for controlling trihalomethanes in drinking 

water: U.S. Environmental Protection Agency, EPA 

600/2–81–156.

U.S. Department of Agriculture, 1994, State Soil 

Geographic (STATSGO) database for Alabama: U.S. 

Department of Agriculture, Natural Resources 

Conservation Service, Soil Survey Division, accessed 

July 31, 2001, at URL http://www.ftw.nrcs.usda.gov/

stat_data.html.

U.S. Environmental Protection Agency, 1981, Clean lakes 

program guidance manual: U.S. Environmental 

Protection Agency, EPA 440/5–81–003.

——— 1986, Ambient water quality criteria for 

bacteria—1986: U.S. Environmental Protection 

Agency, EPA–440/5–84–002.

——— 1989, Guidelines for the preparation of the 1990 

State water quality assessment (section 305(b)): 

Washington, D.C., Office of Water.

——— 1993, Preventing waterborne disease—A focus on 

EPA’s research: U.S. Environmental Protection Agency, 

EPA–640/K–93/001.

——— 1996a, Safe drinking water act amendments of 

1996—General guide to provisions: U.S. 

Environmental Protection Agency, Office of Water, 

EPA–810–S–96–001, 20 p.

——— 1996b, Information Collection Rule—Summary for 

the public: U.S. Environmental Protection Agency, 

Office of Water, EPA 811–F–96–001, 3 p.

——— 1996c, National primary drinking water 

regulations—Monitoring requirements for public 

drinking water supplies: Federal Register 40 CFR, part 

141, v. 61, no. 94, p. 24353–24388.

——— 1998, National primary drinking water 

regulations—Disinfectants and disinfection byproducts—Final rule: Federal Register 40 CFR, parts 9, 

141, and 142, v. 63, no. 241, p. 69389–69476.

——— 1999, Information Collection Rule, Office of 

Ground Water and Drinking Water: accessed 

December 6, 1999, at URL http:// www.epa.gov/

OGWDW/icr.html.

——— 2000, Envirofacts Warehouse—Information 

Collection Rule, query form for the State of Alabama: 

accessed September 15, 2000, at URL 

http://www.epa.gov/enviro/html/icr/state/AL.html.

Vollenweider, R.A., 1968, Scientific fundamentals of the 

eutrophication of lakes and flowing waters, with 

particular reference to nitrogen and phosphorus as 

factors in eutrophication: Paris, France, OECD 

Technical Report DA5/C51/68.27, 159 p.

——— 1969, Possibilities and limits of elementary models 

concerning the budget of substances in lakes: Arch. 

Hydrobiol., v. 66, p. 1–36.

——— 1975, Input-output models with special reference to 

the phosphorus loading concept in limnology: 

Schweizische Zeitshrift fuer Hydrologie, v. 37, 

p. 53–84.

——— 1976, Advances in defining critical loading levels for 

phosphorus in lake eutrophication: Mem. Ist. Ital. 

Idrobiol, v. 33, p. 53–83.

Vollenweider, R.A., and Kerekes, J., 1980, The loading 

concept as basis for controlling 

eutrophication—Philosophy and preliminary results of 

the OECD program on eutrophication: Progress in 

Water Technology, v. 12, p. 5–38.

Wetzel, R.G., 1983, Limnology (2d ed.): Fort Worth, Tex., 

Saunders College Publishing, 766 p.

Wilde, F.D., and Radtke, D.B., 1998, eds., Field 

measurements—National field manual for the 

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

Survey Techniques of Water-Resources Investigations, 

book 9, chap. A6.

Wilde, F.D., Radtke, D.B., Gibs, J., and Iwatsubo, R.T., 

1998, Preparations for water sampling—National field 

manual for the collection of water-quality data: U.S. 

Geological Survey Techniques of Water-Resources 

Investigations, book 9, chap. A1.

——— 1999a, Collection of water samples—National field 

manual for the collection of water-quality data: U.S. 

Geological Survey Techniques of Water-Resources 

Investigations, book 9, chap. A4.

——— 1999b, Processing of water samples—National field 

manual for the collection of water-quality data: U.S. 

Geological Survey Techniques of Water-Resources 

Investigations, book 9, chap. A5.

Yeasted, J.G., and Moret, F.M.M., 1978, Empirical insights 

into lake response to nutrient loadings, with application 

to models of phosphorus in lakes: Environmental 

Science and Technology, v. 12, no. 2, p. 195–201.
$SSHQGL[HV 

$SSHQGL[HV


$VVHVVPHQWRI:DWHU4XDOLW\&RQGLWLRQVLQWKH-%&RQYHUVH/DNH:DWHUVKHG0RELOH&RXQW\$ODEDPD¥

Appendix 1. Summary of descriptive statistics for selected surface-water sites in the J.B. Converse Lake watershed, Mobile Count

October 1990–June 1998

[NWIS, National Water Information System; ft3/s, cubic feet per second; μS/cm at 25 °C, microsiemens per centimeter at 25 degrees Celsius; mm, millimeter; mg/L, 

per 100 milliliters; --, missing data; <, less than; *, estimated; μg/L, microgram per liter; MBAS, methylene blue activated substances; nm, nanometer; cm-1, per cent

dissolved organic carbon; m, meter]

Big Creek at County Road 63 near Wilmer, 02479945 (site BIG)

1:,6

3$5$

0(7(5

&2'(

:$7(548$/,7<&2167,78(17 6$03/( 6,=(

'(6&5,37,9(67$7,67,&6 3(5&(17

0$;,080 0,1,080 0($1   

0

00061 Discharge, instantaneous (ft3/s) 82 1,050 15 79 224 81 

00095 Specific conductance (μS/cm at 25 °C) 80 49 19 25 30 26 

00400 Field pH, whole water (standard unit) 62 6.6 4.5 5.6 6.2 5.9 00020 Air temperature (°C) 58 34.1 5.0 22.3 33.0 28.8 

00010 Water temperature (°C) 81 30.0 7.8 17.9 24.3 22.6 

00025 Air pressure (mm of Hg) 64 772 750 760 767 763 700300 Dissolved oxygen (mg/L) 60 11 6 8 10 9 00301 Dissolved oxygen (percent of saturation) 59 96 63 83 92 89 31625 Fecal coliform (col/100 mL) 58 6,000 20 468 2,095 263 131673 Fecal streptococcus (col/100 mL) 60 9,000 11 652 2,465 703 231633 Escherichia coli (col/100 mL) 19 1,900 19 435 1,900 400 1

00900 Hardness, total (mg/L as CaCO3) 31 7.0 4.0 5.2 7.0 6.0 

00904 Noncarbonate hardness, dissolved 

(mg/L as CaCO3)

24 5.0 1.0 3.4 5.0 4.0 

00915 Calcium, dissolved (mg/L as Ca) 32 1.1 0.6 0.8 1.1 1.0 00925 Magnesium, dissolved (mg/L as Mg) 32 1.0 0.5 0.7 1.0 0.8 00930 Sodium, dissolved (mg/L as Na) 32 2.3 1.1 1.8 2.2 2.0 00935 Potassium, dissolved (mg/L as K) 32 0.9 0.3 0.5 0.8 0.6 00452 Carbonate, dissolved (mg/L as CO3) 60 0.0 -- -- -- -- 

00453 Bicarbonate, dissolved (mg/L as HCO3) 60 5.0 0.0 1.9 5.0 3.0 

39086 Alkalinity, dissolved (mg/L as CaCO3) 60 4 0 2 4 2 

00410 Acid-neutralizing capacity, field 

(mg/L as CaCO3)

60 5.0 0.0 2.7 5.0 3.0 

00945 Sulfate, dissolved (mg/L as SO4) 32 2.1 0.4 1.1 2.0 1.7 
$

SSHQGL[HV

Big Creek at County Road 63 near Wilmer, 02479945 (site BIG)

1:,6

3$5$

0(7(5

&2'(

:$7(548$/,7<&2167,78(17 6$03/( 6,=(

'(6&5,37,9(67$7,67,&6 3(5&(17

0$;,080 0,1,080 0($1   

0

00940 Chloride, dissolved (mg/L as Cl) 42 10.0 2.2 3.8 5.2 4.0 00950 Fluoride, dissolved (mg/L as F) 32 <0.100 <0.100 -- <0.100 <0.100 71870 Bromide, dissolved (mg/L as Br) 15 <0.05 <0.05 -- <0.05 <0.05 00955 Silica, dissolved (mg/L as SiO2) 32 8.5 3.7 6.1 7.7 6.8 70300 Total dissolved solids, residue at 180 °C 

(mg/L)

32 72.0 10.0 26.0 53.2 30.8 

70301 Total dissolved solids (mg/L) 29 24.0 15.0 18.1 23.0 19.0 80154 Suspended sediment concentration (mg/L) 15 25.0 4.0 11.3 25.0 19.0 00615 Nitrite, total (mg/L as N) 48 0.01 <0.01 0.010* 0.01 <0.01 00613 Nitrite, dissolved (mg/L as N) 34 0.01 <0.01 -- 0.01 <0.01 00620 Nitrate, total (mg/L as N) 10 0.55 0.16 0.30 0.55 0.40 00630 Nitrite plus nitrate, total (mg/L as N) 48 0.70 0.10 0.38 0.66 0.50 00631 Nitrite plus nitrate, dissolved (mg/L as N) 48 0.70 0.02 0.38 0.66 0.51 00610 Ammonia, total (mg/L as N) 47 0.08 <0.010 0.03* 0.05 *0.04 00608 Ammonia, dissolved (mg/L as N) 32 0.09 0.01 0.04 0.08 0.04 00605 Organic nitrogen, total (mg/L as N) 36 0.72 0.15 0.31 0.58 0.39 00600 Nitrogen, total (mg/L as N) 37 1.10 0.45 0.73 0.97 0.84 00625 Ammonia plus organic nitrogen, total 

(mg/L as N)

48 0.74 <0.200 0.32* 0.56 *0.36 

00665 Phosphorus, total (mg/L as P) 48 0.080 <0.01 0.021* 0.050 0.030 00666 Phosphorus, dissolved (mg/L as P) 47 0.070 <0.01 0.015* *0.050 *0.020 00671 Phosphorus, ortho (mg/L as P) 47 0.010 <0.01 0.010* *0.010 *0.010 01020 Boron, dissolved (μg/L as B) 32 48 <9 *10 36 6 <

01045 Iron, total (μg/L as Fe) 32 1,200 60 439 1,025 608 3

01046 Iron, dissolved (μg/L as Fe) 32 560 50 215 534 278 1

01055 Manganese, total (μg/L as Mn) 32 76 9 37 68 51 

01056 Manganese, dissolved (μg/L as Mn) 32 69 6 32 62 48 

Appendix 1. Summary of descriptive statistics for selected surface-water sites in the J.B. Converse Lake watershed, Mobile Count

October 1990–June 1998—Continued

[NWIS, National Water Information System; ft3/s, cubic feet per second; μS/cm at 25 °C, microsiemens per centimeter at 25 degrees Celsius; mm, millimeter; mg/L, 

per 100 milliliters; --, missing data; <, less than; *, estimated; μg/L, microgram per liter; MBAS, methylene blue activated substances; nm, nanometer; cm-1, per cent

dissolved organic carbon; m, meter]


$VVHVVPHQWRI:DWHU4XDOLW\&RQGLWLRQVLQWKH-%&RQYHUVH/DNH:DWHUVKHG0RELOH&RXQW\$ODEDPD¥

Big Creek at County Road 63 near Wilmer, 02479945 (site BIG)

1:,6

3$5$

0(7(5

&2'(

:$7(548$/,7<&2167,78(17 6$03/( 6,=(

'(6&5,37,9(67$7,67,&6 3(5&(17

0$;,080 0,1,080 0($1   

0

00680 Organic carbon, total (mg/L as C) 18 11 1.9 5.5 11.0 7.0 00681 Organic carbon, dissolved (mg/L as C) 20 11 1.8 5.1 10.9 7.1 38260 Detergents as MBAS (mg/L) 19 0.4 <0.1 0.109* *0.400 *0.200 32240 Tannin and lignin (mg/L) 20 2 0.5 1.0 2.0 1.4 

Ultraviolet absorbance at 254 nm 

(cm-1 as TOC)

18 0.391 0.131 0.243 -- 0.323 

Ultraviolet absorbance at 254 nm 

(cm-1 as DOC)

18 0.377 0.1 0.216 -- 0.292 

Trihalomethane-formation potential 

(μg/L)

5 2,252 319 1,010 -- 1,356 6

Specific absorbance (mg/L as DOC per cm-1

of DOC)

18 0.083 0.026 0.049 -- 0.062 

Appendix 1. Summary of descriptive statistics for selected surface-water sites in the J.B. Converse Lake watershed, Mobile Count

October 1990–June 1998—Continued

[NWIS, National Water Information System; ft3/s, cubic feet per second; μS/cm at 25 °C, microsiemens per centimeter at 25 degrees Celsius; mm, millimeter; mg/L, 

per 100 milliliters; --, missing data; <, less than; *, estimated; μg/L, microgram per liter; MBAS, methylene blue activated substances; nm, nanometer; cm-1, per cent

dissolved organic carbon; m, meter]
$

SSHQGL[HV

Juniper Creek at Glenwood Road near Fairview, 02479948 (site JUN)

1:,6

3$5$

0(7(5

&2'(

:$7(548$/,7<&2167,78(17 6$03/( 6,=(

'(6&5,37,9(67$7,67,&6 3(5&(17

0$;,080 0,1,080 0($1   

0

00061 Discharge, instantaneous (ft3/s) 56 126 7 23 86 22 00095 Specific conductance (μS/cm at 25 °C) 55 32 18 26 30 27 2

00400 Field pH, whole water (standard unit) 56 7 5.5 6.1 6.5 6.2 00020 Air temperature (°C) 51 31 6.4 21.4 31.0 27.0 2

00010 Water temperature (°C) 56 23.6 9.3 17.5 23.1 21.4 

00025 Air pressure (mm of Hg) 56 773 752 760 766 762 7600300 Dissolved oxygen (mg/L) 52 10.6 6.7 8.6 10.3 9.3 00301 Dissolved oxygen (percent of saturation) 52 120 75 89 99 92 31625 Fecal coliform (col/100 mL) 54 10,000 16 887 3,900 755 331673 Fecal streptococcus (col/100 mL) 55 22,000 50 2,020 18,400 1,000 431633 Escherichia coli (col/100 mL) 20 16,000 160 2,606 15,850 2,250 800900 Hardness, total (mg/L as CaCO3) 26 14 5 6 12 6 

00904 Noncarbonate hardness, dissolved 

(mg/L as CaCO3)

25 4 0 3 4 3 

00915 Calcium, dissolved (mg/L as Ca) 26 4.2 0.8 1.2 3.3 1.2 00925 Magnesium, dissolved (mg/L as Mg) 26 0.9 0.7 0.8 0.9 0.8 00930 Sodium, dissolved (mg/L as Na) 26 2.6 1.1 2.0 2.6 2.1 00935 Potassium, dissolved (mg/L as K) 26 0.8 0.3 0.5 0.8 0.6 00452 Carbonate, dissolved (mg/L as CO3) 56 0 -- -- -- -- 

00453 Bicarbonate, dissolved (mg/L as HCO3) 56 23 1 4 6 5 

39086 Alkalinity, dissolved (mg/L as CaCO3) 56 19 1 3 5 4 

00410 Acid-neutralizing capacity, field 

(mg/L as CaCO3)

56 20 2 4 6 5 

00945 Sulfate, dissolved (mg/L as SO4) 26 1.9 0.2 0.7 1.7 0.9 

Appendix 1. Summary of descriptive statistics for selected surface-water sites in the J.B. Converse Lake watershed, Mobile Count

October 1990–June 1998—Continued

[NWIS, National Water Information System; ft3/s, cubic feet per second; μS/cm at 25 °C, microsiemens per centimeter at 25 degrees Celsius; mm, millimeter; mg/L, 

per 100 milliliters; --, missing data; <, less than; *, estimated; μg/L, microgram per liter; MBAS, methylene blue activated substances; nm, nanometer; cm-1, per cent

dissolved organic carbon; m, meter]


$VVHVVPHQWRI:DWHU4XDOLW\&RQGLWLRQVLQWKH-%&RQYHUVH/DNH:DWHUVKHG0RELOH&RXQW\$ODEDPD¥

Juniper Creek at Glenwood Road near Fairview, 02479948 (site JUN)

1:,6

3$5$

0(7(5

&2'(

:$7(548$/,7<&2167,78(17 6$03/( 6,=(

'(6&5,37,9(67$7,67,&6 3(5&(17

0$;,080 0,1,080 0($1   

0

00940 Chloride, dissolved (mg/L as Cl) 26 4.5 3.1 3.8 4.4 4.0 00950 Fluoride, dissolved (mg/L as F) 26 <0.1 <0.1 <0.1 <0.1 <0.1 71870 Bromide, dissolved (mg/L as Br)00955 Silica, dissolved (mg/L as SiO2) 26 7.2 5.0 6.4 7.2 6.8 

70300 Total dissolved solids, residue at 180 °C 

(mg/L)

26 72.0 9.0 26.8 72.0 31.3 

70301 Total dissolved solids (mg/L) 26 30.0 17.0 19.7 26.9 20.0 80154 Suspended sediment concentration (mg/L) 16 123.0 5.0 39.6 123.0 76.0 00615 Nitrite, total (mg/L as N) 42 0.04 <0.01 0.006* 0.01 0.01 00613 Nitrite, dissolved (mg/L as N) 28 0.01 <0.01 -- 0.01 <0.01 00620 Nitrate, total (mg/L as N) 11 0.51 0.01 0.32 0.51 0.42 00630 Nitrite plus nitrate, total (mg/L as N) 41 0.60 0.20 0.45 0.58 0.50 00631 Nitrite plus nitrate, dissolved (mg/L as N) 42 0.62 0.02 0.44 0.60 0.52 00610 Ammonia, total (mg/L as N) 41 0.07 <0.10 0.02* *0.04 *0.03 00608 Ammonia, dissolved (mg/L as N) 26 0.11 0.01 0.02 0.09 0.03 00605 Organic nitrogen, total (mg/L as N) 21 0.96 0.16 0.34 0.93 0.37 00600 Nitrogen, total (mg/L as N) 22 1.30 0.34 0.75 1.24 0.82 00625 Ammonia plus organic nitrogen, total 

(mg/L as N)

42 0.99 <0.2 0.246* 0.65 0.3 

00665 Phosphorus, total (mg/L as P) 42 0.85 <0.01 0.040* 0.08 *0.030 00666 Phosphorus, dissolved (mg/L as P) 41 0.05 <0.01 0.014* *0.040 *0.020 00671 Phosphorus, ortho (mg/L as P) 41 0.02 <0.01 0.009* *0.010 *0.010 01020 Boron, dissolved (μg/L as B) 26 27 <10 9* 23 7 <

01045 Iron, total (μg/L as Fe) 26 4,500 150 519 3,142 490 3

01046 Iron, dissolved (μg/L as Fe) 26 240 30 132 240 170 1

01055 Manganese, total (μg/L as Mn) 26 110 10 31 89 34 

01056 Manganese, dissolved (μg/L as Mn) 26 48 5.0 19 45 25 

Appendix 1. Summary of descriptive statistics for selected surface-water sites in the J.B. Converse Lake watershed, Mobile Count

October 1990–June 1998—Continued

[NWIS, National Water Information System; ft3/s, cubic feet per second; μS/cm at 25 °C, microsiemens per centimeter at 25 degrees Celsius; mm, millimeter; mg/L, 

per 100 milliliters; --, missing data; <, less than; *, estimated; μg/L, microgram per liter; MBAS, methylene blue activated substances; nm, nanometer; cm-1, per cent

dissolved organic carbon; m, meter]
$

SSHQGL[HV

Juniper Creek at Glenwood Road near Fairview, 02479948 (site JUN)

1:,6

3$5$

0(7(5

&2'(

:$7(548$/,7<&2167,78(17 6$03/( 6,=(

'(6&5,37,9(67$7,67,&6 3(5&(17

0$;,080 0,1,080 0($1   

0

00680 Organic carbon, total (mg/L as C) 20 15.0 1.3 5.7 14.9 9.9 00681 Organic carbon, dissolved (mg/L as C) 20 11.0 1.1 5.0 11.0 8.9 38260 Detergents as MBAS (mg/L) 19 0.8 <0.1 0.1* *0.8 *0.1 <32240 Tannin and lignin (mg/L) 20 3.2 0.3 1.1 3.2 1.5 

Ultraviolet absorbance at 254 nm

 (cm-1 as TOC)

18 0.618 0.089 0.243 -- 0.351 

Ultraviolet absorbance at 254 nm 

(cm-1 as DOC)

18 0.502 0.065 0.192 -- 0.285 

Specific absorbance (mg/L as DOC per cm-1

of DOC)

18 0.110 0.009 0.052 -- 0.078 

Appendix 1. Summary of descriptive statistics for selected surface-water sites in the J.B. Converse Lake watershed, Mobile Count

October 1990–June 1998—Continued

[NWIS, National Water Information System; ft3/s, cubic feet per second; μS/cm at 25 °C, microsiemens per centimeter at 25 degrees Celsius; mm, millimeter; mg/L, 

per 100 milliliters; --, missing data; <, less than; *, estimated; μg/L, microgram per liter; MBAS, methylene blue activated substances; nm, nanometer; cm-1, per cent

dissolved organic carbon; m, meter]


$VVHVVPHQWRI:DWHU4XDOLW\&RQGLWLRQVLQWKH-%&RQYHUVH/DNH:DWHUVKHG0RELOH&RXQW\$ODEDPD¥

Collins Creek at Glenwood Road near Fairview, 02479950 (site COL)

1:,6

3$5$

0(7(5

&2'(

:$7(548$/,7<&2167,78(17 6$03/( 6,=(

'(6&5,37,9(67$7,67,&6 3(5&(17

0$;,080 0,1,080 0($1   

0

00061 Discharge, instantaneous (ft3/s) 56 90 7.8 18.6 46.4 18.8 

00095 Specific conductance (μS/cm at 25 °C) 57 35 20 24 30 26 

00400 Field pH, whole water (standard unit) 56 7.1 5.3 6.1 6.5 6.3 00020 Air temperature (°C) 53 35.2 6.6 21.9 32.6 28.7 

00010 Water temperature (°C) 57 25.3 9 18.1 24.1 22.6 

00025 Air pressure (mm of Hg) 55 772 751 760 768 763 700300 Dissolved oxygen (mg/L) 55 11.0 6.2 8.3 10.3 9.1 00301 Dissolved oxygen (percent of saturation) 53 97 70 88 96 92 31625 Fecal coliform (col/100 mL) 52 10,000 36 545 2,740 378 131673 Fecal streptococcus (col/100 mL) 56 26,000 12 1,239 6,060 758 331633 Escherichia coli (col/100 mL) 20 9,200 92 1,120 8,930 1,075 3

00900 Hardness, total (mg/L as CaCO3) 26 17 3 6 15 6 

00904 Noncarbonate hardness, dissolved 

(mg/L as CaCO3)

26 8 0 2 6 2 

00915 Calcium, dissolved (mg/L as Ca) 26 5.9 0.7 1.5 5.2 1.5 00925 Magnesium, dissolved (mg/L as Mg) 26 0.6 0.4 0.5 0.6 0.5 00930 Sodium, dissolved (mg/L as Na) 26 2.4 1.6 2.0 2.4 2.2 00935 Potassium, dissolved (mg/L as K) 26 0.7 0.3 0.4 0.7 0.6 00452 Carbonate, dissolved (mg/L as CO3) 56 0 -- -- -- -- 

00453 Bicarbonate, dissolved (mg/L as HCO3) 56 19 0 5 8 5 

39086 Alkalinity, dissolved (mg/L as CaCO3) 56 15 0 4 6 4 

00410 Acid-neutralizing capacity, field 

(mg/L as CaCO3)

56 18 2 5 7 5 

00945 Sulfate, dissolved (mg/L as SO4) 26 1.6 0.5 1.0 1.6 1.3 

Appendix 1. Summary of descriptive statistics for selected surface-water sites in the J.B. Converse Lake watershed, Mobile Coun

October 1990–June 1998—Continued

[NWIS, National Water Information System; ft3/s, cubic feet per second; μS/cm at 25 °C, microsiemens per centimeter at 25 degrees Celsius; mm, millimeter; mg/L, 

per 100 milliliters; --, missing data; <, less than; *, estimated; μg/L, microgram per liter; MBAS, methylene blue activated substances; nm, nanometer; cm-1, per cent

dissolved organic carbon; m, meter]
$

SSHQGL[HV

Collins Creek at Glenwood Road near Fairview, 02479950 (site COL)

1:,6

3$5$

0(7(5

&2'(

:$7(548$/,7<&2167,78(17 6$03/( 6,=(

'(6&5,37,9(67$7,67,&6 3(5&(17

0$;,080 0,1,080 0($1   

0

00940 Chloride, dissolved (mg/L as Cl) 26 4.2 2.5 3.5 4.1 3.6 00950 Fluoride, dissolved (mg/L as F) 26 <0.1 <0.1 -- -- -- 71870 Bromide, dissolved (mg/L as Br)00955 Silica, dissolved (mg/L as SiO2) 26 6.9 4.5 6.1 6.9 6.5 70300 Total dissolved solids, residue at 180 °C 

(mg/L)

26 86 10 24.5 67.1 28.3 

70301 Total dissolved solids (mg/L) 26 30 16 18.3 26.9 19.0 80154 Suspended sediment concentration (mg/L) 16 370 2 42.1 370.0 27.5 00615 Nitrite, total (mg/L as N) 43 0.02 <0.01 0.007* *0.010 <0.01 00613 Nitrite, dissolved (mg/L as N) 28 <0.01 <0.01 -- <0.01 <0.01 00620 Nitrate, total (mg/L as N) 8 0.24 0.07 0.15 0.24 0.18 00630 Nitrite plus nitrate, total (mg/L as N) 43 0.30 0.10 0.18 0.28 0.20 00631 Nitrite plus nitrate, dissolved (mg/L as N) 43 0.27 0.02 0.17 0.24 0.20 00610 Ammonia, total (mg/L as N) 42 0.05 -- 0.02* *0.04 *0.02 00608 Ammonia, dissolved (mg/L as N) 27 0.07 <0.01 0.021 0.06 *0.03 00605 Organic nitrogen, total (mg/L as N) 22 0.51 0.19 0.27 0.51 0.33 00600 Nitrogen, total (mg/L as N) 21 0.67 0.34 0.46 0.66 0.52 00625 Ammonia plus organic nitrogen, total 

(mg/L as N)

43 0.53 -- 0.22* *0.47 *0.26 

00665 Phosphorus, total (mg/L as P) 43 0.04 <0.01 0.017* *0.040 *0.020 00666 Phosphorus, dissolved (mg/L as P) 42 0.04 <0.01 0.012* *0.040 0.01 00671 Phosphorus, ortho (mg/L as P) 42 0.02 <0.01 0.008* *0.010 *0.010 01020 Boron, dissolved (μg/L as B) 26 45 <10.00 10* 22 8 <

01045 Iron, total (μg/L as Fe) 26 930 270 586 920 700 6

01046 Iron, dissolved (μg/L as Fe) 26 600 60 256 558 363 2

01055 Manganese, total (μg/L as Mn) 26 50 15 26 48 30 

01056 Manganese, dissolved (μg/L as Mn) 26 40 10 20 38 23 

Appendix 1. Summary of descriptive statistics for selected surface-water sites in the J.B. Converse Lake watershed, Mobile Count

October 1990–June 1998—Continued

[NWIS, National Water Information System; ft3/s, cubic feet per second; μS/cm at 25 °C, microsiemens per centimeter at 25 degrees Celsius; mm, millimeter; mg/L, 

per 100 milliliters; --, missing data; <, less than; *, estimated; μg/L, microgram per liter; MBAS, methylene blue activated substances; nm, nanometer; cm-1, per cent

dissolved organic carbon; m, meter]


$VVHVVPHQWRI:DWHU4XDOLW\&RQGLWLRQVLQWKH-%&RQYHUVH/DNH:DWHUVKHG0RELOH&RXQW\$ODEDPD¥

Collins Creek at Glenwood Road near Fairview, 02479950 (site COL)

1:,6

3$5$

0(7(5

&2'(

:$7(548$/,7<&2167,78(17 6$03/( 6,=(

'(6&5,37,9(67$7,67,&6 3(5&(17

0$;,080 0,1,080 0($1   

0

00680 Organic carbon, total (mg/L as C) 19 13 1.2 5.047 13 7.3 00681 Organic carbon, dissolved (mg/L as C) 20 12 1.2 4.5 11.9 6.0 38260 Detergents as MBAS (mg/L) 19 0.4 <0.1 0.01* *0.4 *0.1 32240 Tannin and lignin (mg/L) 20 3.8 <0.1 0.9* 2.1 1.0 

Ultraviolet absorbance at 254 nm 

(cm-1 as TOC)

18 0.582 0.108 0.227 -- 0.261 

Ultraviolet absorbance at 254 nm 

(cm-1 as DOC)

18 0.453 0.070 0.186 -- 0.243 

Specific absorbance (mg/L as DOC per cm-1

of DOC)

18 0.151 0.010 0.055 -- 0.078 

Appendix 1. Summary of descriptive statistics for selected surface-water sites in the J.B. Converse Lake watershed, Mobile Count

October 1990–June 1998—Continued

[NWIS, National Water Information System; ft3/s, cubic feet per second; μS/cm at 25 °C, microsiemens per centimeter at 25 degrees Celsius; mm, millimeter; mg/L, 

per 100 milliliters; --, missing data; <, less than; *, estimated; μg/L, microgram per liter; MBAS, methylene blue activated substances; nm, nanometer; cm-1, per cent

dissolved organic carbon; m, meter]
$

SSHQGL[HV

Long Branch near Wilmer, 02479955 (site LON)

1:,6

3$5$

0(7(5

&2'(

:$7(548$/,7<&2167,78(17 6$03/( 6,=(

'(6&5,37,9(67$7,67,&6 3(5&(17

0$;,080 0,1,080 0($1   

0

00061 Discharge, instantaneous (ft3/s) 43 26 2.2 6.5 17.4 7.2 00095 Specific conductance (μS/cm at 25 °C) 45 50 22 42 49 45 4

00400 Field pH, whole water (standard unit) 43 7.7 5.2 6.4 7.0 6.6 00020 Air temperature (°C) 42 33.4 7.1 21.5 31.5 28.0 2

00010 Water temperature (°C) 45 25.6 9.2 18.3 25.3 22.7 

00025 Air pressure (mm of Hg) 44 770 751 761 769 764 7600300 Dissolved oxygen (mg/L) 44 10.9 7.1 8.7 10.8 9.5 00301 Dissolved oxygen (percent of saturation) 44 101 77 92 99 96 931625 Fecal coliform (col/100 mL) 43 2,000 28 243 1,320 250 1431673 Fecal streptococcus (col/100 mL) 42 8,700 26 725 1,755 825 431633 Escherichia coli (col/100 mL) 19 1,400 47 257 1,400 290 100900 Hardness, total (mg/L as CaCO3) 22 14 9 11 14 12 

00904 Noncarbonate hardness, dissolved 

(mg/L as CaCO3)

22 8 0 5 8 6 

00915 Calcium, dissolved (mg/L as Ca) 22 3.6 2.1 2.8 3.6 3.0 00925 Magnesium, dissolved (mg/L as Mg) 22 1.4 0.9 1.1 1.4 1.2 00930 Sodium, dissolved (mg/L as Na) 22 2.9 1.9 2.4 2.9 2.6 00935 Potassium, dissolved (mg/L as K) 22 1.4 0.6 0.9 1.4 1.0 00452 Carbonate, dissolved (mg/L as CO3) 43 0 -- -- -- -- 

00453 Bicarbonate, dissolved (mg/L as HCO3) 43 15 3 8 15 9 

39086 Alkalinity, dissolved (mg/L as CaCO3) 43 12 2 7 12 8 

00410 Acid-neutralizing capacity, field 

(mg/L as CaCO3)

43 13 3 8 13 9 

00945 Sulfate, dissolved (mg/L as SO4) 22 5.1 1.2 2.6 4.9 3.5 

Appendix 1. Summary of descriptive statistics for selected surface-water sites in the J.B. Converse Lake watershed, Mobile Count

October 1990–June 1998—Continued

[NWIS, National Water Information System; ft3/s, cubic feet per second; μS/cm at 25 °C, microsiemens per centimeter at 25 degrees Celsius; mm, millimeter; mg/L, 

per 100 milliliters; --, missing data; <, less than; *, estimated; μg/L, microgram per liter; MBAS, methylene blue activated substances; nm, nanometer; cm-1, per cent

dissolved organic carbon; m, meter]


$VVHVVPHQWRI:DWHU4XDOLW\&RQGLWLRQVLQWKH-%&RQYHUVH/DNH:DWHUVKHG0RELOH&RXQW\$ODEDPD¥

Long Branch near Wilmer, 02479955 (site LON)

1:,6

3$5$

0(7(5

&2'(

:$7(548$/,7<&2167,78(17 6$03/( 6,=(

'(6&5,37,9(67$7,67,&6 3(5&(17

0$;,080 0,1,080 0($1   

0

00940 Chloride, dissolved (mg/L as Cl) 22 6.2 3.9 4.8 6.1 5.1 00950 Fluoride, dissolved (mg/L as F) <0.10 <0.10 -- <0.10 <0.10 <0.10 71870 Bromide, dissolved (mg/L as Br)00955 Silica, dissolved (mg/L as SiO2) 22 6.7 4.7 5.9 6.7 6.4 

70300 Total dissolved solids, residue at 180 °C 

(mg/L)

22 90.0 20.0 35.5 82.8 40.0 

70301 Total dissolved solids (mg/L) 21 30.0 24.0 27.4 30.0 28.5 80154 Suspended sediment concentration (mg/L)00615 Nitrite, total (mg/L as N) 30 0.01 -- 0.010* *0.011 *0.010 00613 Nitrite, dissolved (mg/L as N) 18 0.014 -- 0.008* *0.014 *0.010 00620 Nitrate, total (mg/L as N) 15 1.19 0.31 0.67 1.19 0.87 00630 Nitrite plus nitrate, total (mg/L as N) 30 1.20 0.10 0.59 1.09 0.80 00631 Nitrite plus nitrate, dissolved (mg/L as N) 30 1.20 0.02 0.59 1.09 0.76 00610 Ammonia, total (mg/L as N) 29 0.38 0.01 0.06 0.30 0.08 00608 Ammonia, dissolved (mg/L as N) 14 0.11 0.02 0.05 0.11 0.07 00605 Organic nitrogen, total (mg/L as N) 25 1.70 0.10 0.34 1.47 0.32 00600 Nitrogen, total (mg/L as N) 24 2.10 0.42 1.01 2.00 1.20 00625 Ammonia plus organic nitrogen, total 

(mg/L as N)

30 1.7 <0.20 0.36* 0.97 *0.38 

00665 Phosphorus, total (mg/L as P) 30 0.08 <0.01 0.017* 0.05 *0.020 00666 Phosphorus, dissolved (mg/L as P) 29 0.04 <0.01 0.013* *0.040 *0.017 00671 Phosphorus, ortho (mg/L as P) 28 0.01 -- 0.010* *0.010 *0.010 01020 Boron, dissolved (μg/L as B) 22 31 <10 12* 25 11 

01045 Iron, total (μg/L as Fe) 22 6,400 350 1,058 5,695 1,225 6

01046 Iron, dissolved (μg/L as Fe) 22 1,000 30 294 934 390 2

01055 Manganese, total (μg/L as Mn) 22 280 20 56 252 63 

01056 Manganese, dissolved (μg/L as Mn) 22 80 15 37 79 52 

Appendix 1. Summary of descriptive statistics for selected surface-water sites in the J.B. Converse Lake watershed, Mobile Count

October 1990–June 1998—Continued

[NWIS, National Water Information System; ft3/s, cubic feet per second; μS/cm at 25 °C, microsiemens per centimeter at 25 degrees Celsius; mm, millimeter; mg/L, 

per 100 milliliters; --, missing data; <, less than; *, estimated; μg/L, microgram per liter; MBAS, methylene blue activated substances; nm, nanometer; cm-1, per cent

dissolved organic carbon; m, meter]
$

SSHQGL[HV

Long Branch near Wilmer, 02479955 (site LON)

1:,6

3$5$

0(7(5

&2'(

:$7(548$/,7<&2167,78(17 6$03/( 6,=(

'(6&5,37,9(67$7,67,&6 3(5&(17

0$;,080 0,1,080 0($1   

0

00680 Organic carbon, total (mg/L as C) 19 16 1.2 4.8 16.0 6.4 00681 Organic carbon, dissolved (mg/L as C) 20 15 1.2 4.2 14.6 5.6 38260 Detergents as MBAS (mg/L) 18 0.3 <0.10 *0.07 *0.3 *0.1 32240 Tannin and lignin (mg/L) 20 1.4 0.3 0.7 1.4 0.8 

Ultraviolet absorbance at 254 nm 

(cm-1 as TOC)

17 0.267 0.098 0.176 -- 0.199 

Ultraviolet absorbance at 254 nm 

(cm-1 as DOC)

18 0.214 0.068 0.135 -- 0.172 

Specific absorbance (mg/L as DOC per cm-1

of DOC)

18 0.123 0.007 0.047 -- 0.061 

Appendix 1. Summary of descriptive statistics for selected surface-water sites in the J.B. Converse Lake watershed, Mobile Count

October 1990–June 1998—Continued

[NWIS, National Water Information System; ft3/s, cubic feet per second; μS/cm at 25 °C, microsiemens per centimeter at 25 degrees Celsius; mm, millimeter; mg/L, 

per 100 milliliters; --, missing data; <, less than; *, estimated; μg/L, microgram per liter; MBAS, methylene blue activated substances; nm, nanometer; cm-1, per cent

dissolved organic carbon; m, meter]


$VVHVVPHQWRI:DWHU4XDOLW\&RQGLWLRQVLQWKH-%&RQYHUVH/DNH:DWHUVKHG0RELOH&RXQW\$ODEDPD¥

Boggy Branch near Wilmer, 02479960 (site BOG)

1:,6

3$5$

0(7(5

&2'(

:$7(548$/,7<&2167,78(17 6$03/( 6,=(

'(6&5,37,9(67$7,67,&6 3(5&(17

0$;,080 0,1,080 0($1   

0

00061 Discharge, instantaneous (ft3/s) 43 60 1.3 7.1 21 7.2 

00095 Specific conductance (μS/cm at 25 °C) 43 48 19 30 36 32 

00400 Field pH, whole water (standard unit) 43 6.4 5 5.8 6.3 6.1 00020 Air temperature (°C) 41 35 -0.1 20.1 31.2 26.7 

00010 Water temperature (°C) 43 26.4 4.8 17.9 26.4 23.7 

00025 Air pressure (mm of Hg) 43 770 752 761 770 764 700300 Dissolved oxygen (mg/L) 43 11 3.7 7.2 9.9 8.2 00301 Dissolved oxygen (percent of saturation) 43 101 41 74 92 81 31625 Fecal coliform (col/100 mL) 42 6,000 24 584 4,330 453 31673 Fecal streptococcus (col/100 mL) 43 8,800 10 948 4,480 1,100 331633 Escherichia coli (col/100 mL) 20 4,200 57 643 4,170 548 

00900 Hardness, total (mg/L as CaCO3) 22 8 6 7 8 7 

00904 Noncarbonate hardness, dissolved 

(mg/L as CaCO3)

22 6 0 4 6 4 

00915 Calcium, dissolved (mg/L as Ca) 22 1.4 0.9 1.1 1.4 1.2 00925 Magnesium, dissolved (mg/L as Mg) 22 1.2 0.8 1.0 1.2 1.1 00930 Sodium, dissolved (mg/L as Na) 22 3 1.4 2.2 3.0 2.5 00935 Potassium, dissolved (mg/L as K) 22 1.3 0.3 0.6 1.2 0.7 00452 Carbonate, dissolved (mg/L as CO3) 43 0 -- -- -- -- 

00453 Bicarbonate, dissolved (mg/L as HCO3) 43 7 1 3.7 7.0 5.0 

39086 Alkalinity, dissolved (mg/L as CaCO3) 43 6 1 3.1 5.8 4.0 

00410 Acid-neutralizing capacity, field 

(mg/L as CaCO3)

43 7 2 4 7 5 

00945 Sulfate, dissolved (mg/L as SO4) 22 3.5 0.6 1.4 3.3 1.9 

Appendix 1. Summary of descriptive statistics for selected surface-water sites in the J.B. Converse Lake watershed, Mobile Coun

October 1990–June 1998—Continued

[NWIS, National Water Information System; ft3/s, cubic feet per second; μS/cm at 25 °C, microsiemens per centimeter at 25 degrees Celsius; mm, millimeter; mg/L, 

per 100 milliliters; --, missing data; <, less than; *, estimated; μg/L, microgram per liter; MBAS, methylene blue activated substances; nm, nanometer; cm-1, per cent

dissolved organic carbon; m, meter]
$

SSHQGL[HV

Boggy Branch near Wilmer, 02479960 (site BOG)

1:,6

3$5$

0(7(5

&2'(

:$7(548$/,7<&2167,78(17 6$03/( 6,=(

'(6&5,37,9(67$7,67,&6 3(5&(17

0$;,080 0,1,080 0($1   

0

00940 Chloride, dissolved (mg/L as Cl) 22 41 2.9 6.7 36.1 5.5 00950 Fluoride, dissolved (mg/L as F) 22 <0.1 <0.1 -- <0.1 <0.1 71870 Bromide, dissolved (mg/L as Br)00955 Silica, dissolved (mg/L as SiO2) 22 8.6 4.5 6.8 8.6 7.8 70300 Total dissolved solids, residue at 180 °C 

(mg/L)

22 70 14 28.9 65.8 32.5 

70301 Total dissolved solids (mg/L) 22 59 17 22.5 54.1 23.0 80154 Suspended sediment concentration (mg/L) 1 21 -- -- -- -- 00615 Nitrite, total (mg/L as N) 29 0.01 <.01 0.01* 0.01 <0.01 00613 Nitrite, dissolved (mg/L as N) 18 <0.01 <0.01 -- <0.01 <0.01 00620 Nitrate, total (mg/L as N) 6 0.18 0.05 0.12 0.18 0.15 00630 Nitrite plus nitrate, total (mg/L as N) 29 0.3 0.1 0.14 0.25 0.20 00631 Nitrite plus nitrate, dissolved (mg/L as N) 30 0.3 0.06 0.14 0.26 0.17 00610 Ammonia, total (mg/L as N) 28 0.05 <0.01 0.02* 0.04 0.03 00608 Ammonia, dissolved (mg/L as N) 15 0.05 0.01 0.02 0.05 0.03 00605 Organic nitrogen, total (mg/L as N) 24 1.5 0.20 0.36 1.28 0.35 00600 Nitrogen, total (mg/L as N) 26 1.6 0.30 0.52 1.30 0.53 00625 Ammonia plus organic nitrogen, total 

(mg/L as N)

30 1.5 <0.20 0.35* 0.64 0.36 

00665 Phosphorus, total (mg/L as P) 30 0.04 0.04 0.04 0.04 0.02 00666 Phosphorus, dissolved (mg/L as P) 29 0.040 <0.010 0.014* 0.030 0.020 00671 Phosphorus, ortho (mg/L as P) 28 0.020 <0.010 0.007* 0.020 0.010 01020 Boron, dissolved (μg/L as B) 22 34 <10 11* 26 9.0 

01045 Iron, total (μg/L as Fe) 22 2,600 360 1,046 2,465 1,325 9

01046 Iron, dissolved (μg/L as Fe) 22 1,400 80 434 1,318 575 3

01055 Manganese, total (μg/L as Mn) 22 150 42 81 146 99 

01056 Manganese, dissolved (μg/L as Mn) 22 140 33 69 136 80 

Appendix 1. Summary of descriptive statistics for selected surface-water sites in the J.B. Converse Lake watershed, Mobile Count

October 1990–June 1998—Continued

[NWIS, National Water Information System; ft3/s, cubic feet per second; μS/cm at 25 °C, microsiemens per centimeter at 25 degrees Celsius; mm, millimeter; mg/L, 

per 100 milliliters; --, missing data; <, less than; *, estimated; μg/L, microgram per liter; MBAS, methylene blue activated substances; nm, nanometer; cm-1, per cent

dissolved organic carbon; m, meter]


$VVHVVPHQWRI:DWHU4XDOLW\&RQGLWLRQVLQWKH-%&RQYHUVH/DNH:DWHUVKHG0RELOH&RXQW\$ODEDPD¥

Boggy Branch near Wilmer, 02479960 (site BOG)

1:,6

3$5$

0(7(5

&2'(

:$7(548$/,7<&2167,78(17 6$03/( 6,=(

'(6&5,37,9(67$7,67,&6 3(5&(17

0$;,080 0,1,080 0($1   

0

00680 Organic carbon, total (mg/L as C) 20 13 1.9 5.6 12.9 6.9 00681 Organic carbon, dissolved (mg/L as C) 19 10 1.7 5.1 10.0 6.5 38260 Detergents as MBAS (mg/L) 18 0.6 <0.1 0.1* 0.6 0.1 32240 Tannin and lignin (mg/L) 20 7.1 0.5 1.2 6.8 1.4 

Ultraviolet absorbance at 254 nm 

(cm-1 as TOC)

18 0.325 0.144 0.268 -- 0.325 

Ultraviolet absorbance at 254 nm 

(cm-1 as DOC)

18 0.433 0.107 0.221 -- 0.270 

Specific absorbance (mg/L as DOC per cm-1

of DOC)

17 0.096 0.022 0.051 -- 0.064 

Appendix 1. Summary of descriptive statistics for selected surface-water sites in the J.B. Converse Lake watershed, Mobile Count

October 1990–June 1998—Continued

[NWIS, National Water Information System; ft3/s, cubic feet per second; μS/cm at 25 °C, microsiemens per centimeter at 25 degrees Celsius; mm, millimeter; mg/L, 

per 100 milliliters; --, missing data; <, less than; *, estimated; μg/L, microgram per liter; MBAS, methylene blue activated substances; nm, nanometer; cm-1, per cent

dissolved organic carbon; m, meter]
$

SSHQGL[HV

Crooked Creek near Fairview, 02479980 (site CRO)

1:,6

3$5$

0(7(5

&2'(

:$7(548$/,7<&2167,78(17 6$03/( 6,=(

'(6&5,37,9(67$7,67,&6 3(5&(17

0$;,080 0,1,080 0($1   

0

00061 Discharge, instantaneous (ft3/s) 78 239 6.6 17 32 17 00095 Specific conductance (μS/cm at 25 °C) 78 51 22 36 43 38 

00400 Field pH, whole water (standard unit) 62 6.8 5.2 6.3 6.8 6.5 00020 Air temperature (°C) 59 33 1.5 20.7 31.0 26.2 

00010 Water temperature (°C) 78 24.2 8.9 17.8 23.6 21.7 

00025 Air pressure (mm of Hg) 65 773 750 761 771 763 700300 Dissolved oxygen (mg/L) 62 10.3 5.4 8.1 10.0 8.9 00301 Dissolved oxygen (percent of saturation) 62 101 61 84 97 89 31625 Fecal coliform (col/100 mL) 59 2,000 72 349 1,000 440 231673 Fecal streptococcus (col/100 mL) 61 5,800 74 808 2,930 935 531633 Escherichia coli (col/100 mL) 19 1,100 130 449 1,100 640 300900 Hardness, total (mg/L as CaCO3) 32 14 6 9 13 10 

00904 Noncarbonate hardness, dissolved 

(mg/L as CaCO3)

30 5 0 3 5 3 

00915 Calcium, dissolved (mg/L as Ca) 32 4 1.2 2.2 3.9 2.6 00925 Magnesium, dissolved (mg/L as Mg) 32 1 0.5 0.8 1.0 0.9 00930 Sodium, dissolved (mg/L as Na) 32 3.4 1.2 2.5 3.3 2.7 00935 Potassium, dissolved (mg/L as K) 32 1.7 0.5 0.9 1.6 1.1 00452 Carbonate, dissolved (mg/L as CO3) 61 0 -- -- -- -- 

00453 Bicarbonate, dissolved (mg/L as HCO3) 61 14 3 8 14 10 

39086 Alkalinity, dissolved (mg/L as CaCO3) 61 12 3 7 11 8 

00410 Acid-neutralizing capacity, field 

(mg/L as CaCO3)

61 13 4 8 12 9 

00945 Sulfate, dissolved (mg/L as SO4) 32 3 0.8 1.5 2.9 1.8 

Appendix 1. Summary of descriptive statistics for selected surface-water sites in the J.B. Converse Lake watershed, Mobile Count

October 1990–June 1998—Continued

[NWIS, National Water Information System; ft3/s, cubic feet per second; μS/cm at 25 °C, microsiemens per centimeter at 25 degrees Celsius; mm, millimeter; mg/L, 

per 100 milliliters; --, missing data; <, less than; *, estimated; μg/L, microgram per liter; MBAS, methylene blue activated substances; nm, nanometer; cm-1, per cent

dissolved organic carbon; m, meter]


$VVHVVPHQWRI:DWHU4XDOLW\&RQGLWLRQVLQWKH-%&RQYHUVH/DNH:DWHUVKHG0RELOH&RXQW\$ODEDPD¥

Crooked Creek near Fairview, 02479980 (site CRO)

1:,6

3$5$

0(7(5

&2'(

:$7(548$/,7<&2167,78(17 6$03/( 6,=(

'(6&5,37,9(67$7,67,&6 3(5&(17

0$;,080 0,1,080 0($1   

0

00940 Chloride, dissolved (mg/L as Cl) 42 7.5 0.1 4.2 6.3 4.5 00950 Fluoride, dissolved (mg/L as F) 32 <0.1 <0.1 -- <0.1 <0.1 71870 Bromide, dissolved (mg/L as Br) 15 <0.05 <0.05 -- <0.05 <0.05 00955 Silica, dissolved (mg/L as SiO2) 32 7.3 1.5 5.8 7.0 6.6 

70300 Total dissolved solids, residue at 180 °C 

(mg/L)

32 86 12 29.6 61.3 33.8 

70301 Total dissolved solids (mg/L) 31 28 20 24.0 28.0 26.0 80154 Suspended sediment concentration (mg/L) 14 71 1 11.4 71.0 11.8 00615 Nitrite, total (mg/L as N) 48 0.100 <0.010 0.006* 0.010 <0.010 00613 Nitrite, dissolved (mg/L as N) 33 0.020 <0.010 -- <0.010 <0.010 00620 Nitrate, total (mg/L as N) 10 0.43 0.16 0.30 0.43 0.35 00630 Nitrite plus nitrate, total (mg/L as N) 48 0.50 0.10 0.36 0.50 0.40 00631 Nitrite plus nitrate, dissolved (mg/L as N) 48 0.52 0.02 0.37 0.50 0.41 00610 Ammonia, total (mg/L as N) 47 0.05 0.01 0.02 0.04 0.03 00608 Ammonia, dissolved (mg/L as N) 32 0.07 0.01 0.02 0.06 0.03 00605 Organic nitrogen, total (mg/L as N) 31 2.3 0.17 0.37 1.29 0.40 00600 Nitrogen, total (mg/L as N) 33 2.6 0.51 0.75 1.40 0.76 00625 Ammonia plus organic nitrogen, total 

(mg/L as N)

48 2.3 <0.20 0.31* 0.50 0.33 

00665 Phosphorus, total (mg/L as P) 48 0.18 <0.01 0.03* 0.05 0.03 00666 Phosphorus, dissolved (mg/L as P) 47 0.050 <0.010 0.016* 0.040 0.020 00671 Phosphorus, ortho (mg/L as P) 47 0.030 <0.010 0.009* 0.020 0.010 01020 Boron, dissolved (μg/L as B) 32 34 <10 14* 31 13 <

01045 Iron, total (μg/L as Fe) 32 4,900 320 828 2,495 980 7

01046 Iron, dissolved (μg/L as Fe) 32 680 60 272 622 370 2

01055 Manganese, total (μg/L as Mn) 32 100 20 34 94 40 

01056 Manganese, dissolved (μg/L as Mn) 32 53 9 21 52 26 

Appendix 1. Summary of descriptive statistics for selected surface-water sites in the J.B. Converse Lake watershed, Mobile Count

October 1990–June 1998—Continued

[NWIS, National Water Information System; ft3/s, cubic feet per second; μS/cm at 25 °C, microsiemens per centimeter at 25 degrees Celsius; mm, millimeter; mg/L, 

per 100 milliliters; --, missing data; <, less than; *, estimated; μg/L, microgram per liter; MBAS, methylene blue activated substances; nm, nanometer; cm-1, per cent

dissolved organic carbon; m, meter]
$

SSHQGL[HV

Crooked Creek near Fairview, 02479980 (site CRO)

1:,6

3$5$

0(7(5

&2'(

:$7(548$/,7<&2167,78(17 6$03/( 6,=(

'(6&5,37,9(67$7,67,&6 3(5&(17

0$;,080 0,1,080 0($1   

0

00680 Organic carbon, total (mg/L as C) 20 8.2 <0.1 3.6* 6.9 5.2 00681 Organic carbon, dissolved (mg/L as C) 21 8.1 0.10 3.3 8.0 4.7 38260 Detergents as MBAS (mg/L) 20 0.4 <0.1 0.1* 0.2 0.1 32240 Tannin and lignin (mg/L) 21 1 0.1 0.6 1 0.8 

Ultraviolet absorbance at 254 nm 

(cm-1 as TOC)

17 0.268 0.092 0.176 -- 0.238 

Ultraviolet absorbance at 254 nm 

(cm-1 as DOC)

18 0.256 0.065 0.139 -- 0.183 

Trihalomethane-formation potential 

(μg/L)

5 732 171 373 -- 439 2

Specific absorbance (mg/L as DOC per cm-1

of DOC)

18 0.133 0.018 0.060 -- 0.087 

Appendix 1. Summary of descriptive statistics for selected surface-water sites in the J.B. Converse Lake watershed, Mobile Count

October 1990–June 1998—Continued

[NWIS, National Water Information System; ft3/s, cubic feet per second; μS/cm at 25 °C, microsiemens per centimeter at 25 degrees Celsius; mm, millimeter; mg/L, 

per 100 milliliters; --, missing data; <, less than; *, estimated; μg/L, microgram per liter; MBAS, methylene blue activated substances; nm, nanometer; cm-1, per cent

dissolved organic carbon; m, meter]


$VVHVVPHQWRI:DWHU4XDOLW\&RQGLWLRQVLQWKH-%&RQYHUVH/DNH:DWHUVKHG0RELOH&RXQW\$ODEDPD¥

Crooked Creek at mouth near Wilmer, 02479985 (site LCRO)

1:,6

3$5$

0(7(5

&2'(

:$7(548$/,7<&2167,78(17 6$03/( 6,=(

'(6&5,37,9(67$7,67,&6 3(5&(17

0$;,080 0,1,080 0($1   

0

00078 Transparency (m) 15 4.2 0.8 2.3 4.2 3.1 00095 Specific conductance (μS/cm at 25 °C) 123 36 23 27 35 28 

00400 Field pH, whole water (standard unit) 102 7 5 6.2 6.6 6.4 00020 Air temperature (°C) 19 32.7 9.7 22.9 32.7 30.4 

00010 Water temperature (°C) 123 32.1 11.7 21.5 31.0 29.2 

00025 Air pressure (mm of Hg) 28 767 755 762 767 764 700300 Dissolved oxygen (mg/L) 123 10.5 1.1 7.8 10.4 9.1 00301 Dissolved oxygen (percent of saturation) 28 109 70 93 109 96 31625 Fecal coliform (col/100 mL) 20 180 <1 31* 120 26 31673 Fecal streptococcus (col/100 mL) 20 58 <1 14* 54 10 31633 Escherichia coli (col/100 mL) 19 170 <1 31* 170 42 

00900 Hardness, total (mg/L as CaCO3) 8 7 67 7 7 

00904 Noncarbonate hardness, dissolved 

(mg/L as CaCO3)

8 4 23 4 4 

00915 Calcium, dissolved (mg/L as Ca) 8 1.8 1.4 1.7 1.8 1.8 00925 Magnesium, dissolved (mg/L as Mg) 8 0.7 0.6 0.7 0.7 0.7 00930 Sodium, dissolved (mg/L as Na) 8 2.4 1.6 1.9 2.4 2.1 00935 Potassium, dissolved (mg/L as K) 8 0.8 0.5 0.6 0.8 0.7 00452 Carbonate, dissolved (mg/L as CO3) 21 0 -- -- -- -- 

00453 Bicarbonate, dissolved (mg/L as HCO3) 21 8 4 5.5 7.9 6.5 

39086 Alkalinity, dissolved (mg/L as CaCO3) 21 6 3 4.6 6.0 5.0 

00410 Acid-neutralizing capacity, field 

(mg/L as CaCO3)

21 7 4 6 7 7 

00945 Sulfate, dissolved (mg/L as SO4) 8 2.0 <0.2 1.5* 2.0 1.8 

Appendix 1. Summary of descriptive statistics for selected surface-water sites in the J.B. Converse Lake watershed, Mobile Count

October 1990–June 1998—Continued

[NWIS, National Water Information System; ft3/s, cubic feet per second; μS/cm at 25 °C, microsiemens per centimeter at 25 degrees Celsius; mm, millimeter; mg/L, 

per 100 milliliters; --, missing data; <, less than; *, estimated; μg/L, microgram per liter; MBAS, methylene blue activated substances; nm, nanometer; cm-1, per cent

dissolved organic carbon; m, meter]
$

SSHQGL[HV

Crooked Creek at mouth near Wilmer, 02479985 (site LCRO)

1:,6

3$5$

0(7(5

&2'(

:$7(548$/,7<&2167,78(17 6$03/( 6,=(

'(6&5,37,9(67$7,67,&6 3(5&(17

0$;,080 0,1,080 0($1   

0

00940 Chloride, dissolved (mg/L as Cl) 8 4 2.9 3.6 4.0 3.8 00950 Fluoride, dissolved (mg/L as F) 8 <0.1 <0.1 -- <0.1 <0.1 71870 Bromide, dissolved (mg/L as Br)00955 Silica, dissolved (mg/L as SiO2) 8 4 2.5 3.2 4.0 3.7 70300 Total dissolved solids, residue at 180 °C 

(mg/L)

8 30 10 21.8 30.0 29.0 

70301 Total dissolved solids (mg/L) 7 18 15 16.3 18.0 17.0 80154 Suspended sediment concentration (mg/L)00615 Nitrite, total (mg/L as N) 7 <0.01 <0.01 -- <0.01 <0.01 00613 Nitrite, dissolved (mg/L as N) 8 <0.01 <0.01 -- <0.01 <0.01 00630 Nitrite plus nitrate, total (mg/L as N) 7 0.2 <0.1 0.1* 0.2 0.2 00631 Nitrite plus nitrate, dissolved (mg/L as N) 8 0.20 <0.02 0.12* 0.20 0.16 00610 Ammonia, total (mg/L as N) 7 0.04 0.02 0.03 0.04 0.03 00608 Ammonia, dissolved (mg/L as N) 1 <0.01 -- -- -- -- 00605 Organic nitrogen, total (mg/L as N) 4 0.38 0.19 -- -- -- 00600 Nitrogen, total (mg/L as N) 2 0.50 0.48 -- -- -- 00625 Ammonia plus organic nitrogen, total 

(mg/L as N)

7 0.40 <0.20 -- 0.40 0.36 

00665 Phosphorus, total (mg/L as P) 7 0.04 <0.02 -- 0.04 0.03 00666 Phosphorus, dissolved (mg/L as P) 8 0.04 <0.02 -- 0.04 <0.02 00671 Phosphorus, ortho (mg/L as P) 8 <0.01 <0.01 -- <0.01 <0.01 01020 Boron, dissolved (μg/L as B) 7 10 8 9.0 10 10 

01045 Iron, total (μg/L as Fe) 8 660 210 365 660 460 3

01046 Iron, dissolved (μg/L as Fe) 8 310 110 183 310 258 1

01055 Manganese, total (μg/L as Mn) 8 54 8 26 54 43 

01056 Manganese, dissolved (μg/L as Mn) 8 20 2 9.9 20 16 

Appendix 1. Summary of descriptive statistics for selected surface-water sites in the J.B. Converse Lake watershed, Mobile Count

October 1990–June 1998—Continued

[NWIS, National Water Information System; ft3/s, cubic feet per second; μS/cm at 25 °C, microsiemens per centimeter at 25 degrees Celsius; mm, millimeter; mg/L, 

per 100 milliliters; --, missing data; <, less than; *, estimated; μg/L, microgram per liter; MBAS, methylene blue activated substances; nm, nanometer; cm-1, per cent

dissolved organic carbon; m, meter]


$VVHVVPHQWRI:DWHU4XDOLW\&RQGLWLRQVLQWKH-%&RQYHUVH/DNH:DWHUVKHG0RELOH&RXQW\$ODEDPD¥

Crooked Creek at mouth near Wilmer, 02479985 (site LCRO)

1:,6

3$5$

0(7(5

&2'(

:$7(548$/,7<&2167,78(17 6$03/( 6,=(

'(6&5,37,9(67$7,67,&6 3(5&(17

0$;,080 0,1,080 0($1   

0

00680 Organic carbon, total (mg/L as C) 20 16 1.9 5.2 16.0 5.8 00681 Organic carbon, dissolved (mg/L as C) 19 12 1.8 4.4 -- 4.9 38260 Detergents as MBAS (mg/L) 19 0.3 <0.1 0.1* 0.3 0.1 32240 Tannin and lignin (mg/L) 20 1.1 0.3 0.6 1.1 0.8 

Ultraviolet absorbance at 254 nm 

(cm-1 as TOC)

18 0.280 0.096 0.168 -- 0.184 

Ultraviolet absorbance at 254 nm 

(cm-1 as DOC)

18 0.263 0.085 0.151 -- 0.166 

Specific absorbance (mg/L as DOC per cm-1

of DOC)

17 0.092 0.011 0.044 -- 0.057 

Appendix 1. Summary of descriptive statistics for selected surface-water sites in the J.B. Converse Lake watershed, Mobile Count

October 1990–June 1998—Continued

[NWIS, National Water Information System; ft3/s, cubic feet per second; μS/cm at 25 °C, microsiemens per centimeter at 25 degrees Celsius; mm, millimeter; mg/L, 

per 100 milliliters; --, missing data; <, less than; *, estimated; μg/L, microgram per liter; MBAS, methylene blue activated substances; nm, nanometer; cm-1, per cent

dissolved organic carbon; m, meter]
$

SSHQGL[HV

Hamilton Creek at Snow Road near Semmes, 02480002 (site HAM)

1:,6

3$5$

0(7(5

&2'(

:$7(548$/,7<&2167,78(17 6$03/( 6,=(

'(6&5,37,9(67$7,67,&6 3(5&(17

0$;,080 0,1,080 0($1   

0

00061 Discharge, instantaneous (ft3/s) 78 371 11 29 60 23 00095 Specific conductance (μS/cm at 25 °C) 79 42 21 34 41 36 

00400 Field pH, whole water (standard unit) 61 6.6 5.3 6.1 6.5 6.2 00020 Air temperature (°C) 59 34.2 -1.2 21.2 34.0 27.8 

00010 Water temperature (°C) 80 24.2 10.1 18.4 24.0 22.0 

00025 Air pressure (mm of Hg) 63 768 750 760 766 762 700300 Dissolved oxygen (mg/L) 61 9.9 5.2 7.8 9.7 8.7 00301 Dissolved oxygen (percent of saturation) 60 98 60 83 96 86 31625 Fecal coliform (col/100 mL) 57 5,200 26 316 1,100 255 131673 Fecal streptococcus (col/100 mL) 61 19,000 12 1,006 2,380 655 331633 Escherichia coli (col/100 mL) 20 5,800 46 594 5,570 433 200900 Hardness, total (mg/L as CaCO3) 31 9 5 7 9 8 

00904 Noncarbonate hardness, dissolved 

(mg/L as CaCO3)

31 4 1 2 4 3 

00915 Calcium, dissolved (mg/L as Ca) 31 2.5 0.9 1.5 2.3 1.7 00925 Magnesium, dissolved (mg/L as Mg) 31 0.9 0.7 0.8 0.9 0.8 00930 Sodium, dissolved (mg/L as Na) 31 3.7 2.0 3.1 3.7 3.3 00935 Potassium, dissolved (mg/L as K) 31 0.8 0.3 0.5 0.7 0.7 00452 Carbonate, dissolved (mg/L as CO3) 61 0 -- -- -- -- 

00453 Bicarbonate, dissolved (mg/L as HCO3) 61 11 1 6 9 6 

39086 Alkalinity, dissolved (mg/L as CaCO3) 61 9 1 5 8 5 

00410 Acid-neutralizing capacity, field 

(mg/L as CaCO3)

60 10 2 6 9 7 

00945 Sulfate, dissolved (mg/L as SO4) 31 2.4 0.6 1.1 2.2 1.3 

Appendix 1. Summary of descriptive statistics for selected surface-water sites in the J.B. Converse Lake watershed, Mobile Count

October 1990–June 1998—Continued

[NWIS, National Water Information System; ft3/s, cubic feet per second; μS/cm at 25 °C, microsiemens per centimeter at 25 degrees Celsius; mm, millimeter; mg/L, 

per 100 milliliters; --, missing data; <, less than; *, estimated; μg/L, microgram per liter; MBAS, methylene blue activated substances; nm, nanometer; cm-1, per cent

dissolved organic carbon; m, meter]


$VVHVVPHQWRI:DWHU4XDOLW\&RQGLWLRQVLQWKH-%&RQYHUVH/DNH:DWHUVKHG0RELOH&RXQW\$ODEDPD¥

Hamilton Creek at Snow Road near Semmes, 02480002 (site HAM)

1:,6

3$5$

0(7(5

&2'(

:$7(548$/,7<&2167,78(17 6$03/( 6,=(

'(6&5,37,9(67$7,67,&6 3(5&(17

0$;,080 0,1,080 0($1   

0

00940 Chloride, dissolved (mg/L as Cl) 40 7.3 2.3 4.9 6.6 5.1 00950 Fluoride, dissolved (mg/L as F) 30 <0.1 <0.1 -- <0.1 <0.1 71870 Bromide, dissolved (mg/L as Br) 14 0.07 <0.05 -- 0.07 <0.05 00955 Silica, dissolved (mg/L as SiO2) 31 8.5 5.6 6.6 7.8 7.1 

70300 Total dissolved solids, residue at 180 °C 

(mg/L)

31 96.0 12.0 28.6 62.4 34.0 

70301 Total dissolved solids (mg/L) 31 27.0 22.0 23.8 26.4 25.0 80154 Suspended sediment concentration (mg/L) 15 48.0 1.0 18.7 48.0 28.0 00615 Nitrite, total (mg/L as N) 46 0.030 <0.010 0.005* 0.010 <0.010 00613 Nitrite, dissolved (mg/L as N) 31 0.010 <0.010 -- 0.010 <0.010 00620 Nitrate, total (mg/L as N) 9 0.58 0.07 0.39 0.58 0.53 00630 Nitrite plus nitrate, total (mg/L as N) 47 0.60 0.10 0.51 0.60 0.60 00631 Nitrite plus nitrate, dissolved (mg/L as N) 47 0.63 0.07 0.50 0.62 0.57 00610 Ammonia, total (mg/L as N) 46 0.05 0.01 0.02 0.04 0.03 00608 Ammonia, dissolved (mg/L as N) 31 0.06 0.01 0.02 0.06 0.03 00605 Organic nitrogen, total (mg/L as N) 27 0.59 0.18 0.29 0.57 0.35 00600 Nitrogen, total (mg/L as N) 27 1.2 0.56 0.79 1.1 0.86 00625 Ammonia plus organic nitrogen, total 

(mg/L as N)

47 0.6 <0.20 0.24* 0.53 0.28 

00665 Phosphorus, total (mg/L as P) 47 0.11 <0.010 0.021* 0.060 0.030 00666 Phosphorus, dissolved (mg/L as P) 46 0.050 <0.010 0.013* 0.040 0.020 00671 Phosphorus, ortho (mg/L as P) 45 0.02 <0.01 0.009* 0.01 0.01 01020 Boron, dissolved (μg/L as B) 31 27 <10 12* 27 11 <

01045 Iron, total (μg/L as Fe) 31 1,100 270 580 1,040 810 5

01046 Iron, dissolved (μg/L as Fe) 31 600 50 234 516 310 2

01055 Manganese, total (μg/L as Mn) 31 47 10 27 42 33 

01056 Manganese, dissolved (μg/L as Mn) 31 35 10 24 33 29 

Appendix 1. Summary of descriptive statistics for selected surface-water sites in the J.B. Converse Lake watershed, Mobile Count

October 1990–June 1998—Continued

[NWIS, National Water Information System; ft3/s, cubic feet per second; μS/cm at 25 °C, microsiemens per centimeter at 25 degrees Celsius; mm, millimeter; mg/L, 

per 100 milliliters; --, missing data; <, less than; *, estimated; μg/L, microgram per liter; MBAS, methylene blue activated substances; nm, nanometer; cm-1, per cent

dissolved organic carbon; m, meter]
$

SSHQGL[HV

Hamilton Creek at Snow Road near Semmes, 02480002 (site HAM)

1:,6

3$5$

0(7(5

&2'(

:$7(548$/,7<&2167,78(17 6$03/( 6,=(

'(6&5,37,9(67$7,67,&6 3(5&(17

0$;,080 0,1,080 0($1   

0

00680 Organic carbon, total (mg/L as C) 20 12 1.1 4.2 11.8 5.7 00681 Organic carbon, dissolved (mg/L as C) 20 7.3 1 3.6 7.3 5.2 38260 Detergents as MBAS (mg/L) 18 0.7 <0.1 0.1* 0.7 0.1 32240 Tannin and lignin (mg/L) 20 2.4 0.3 0.8 2.4 0.9 

Ultraviolet absorbance at 254 nm 

(cm-1 as TOC)

18 0.406 0.111 0.205 -- 0.241 

Ultraviolet absorbance at 254 nm 

(cm-1 as DOC)

19 0.354 0.068 0.162 -- 0.194 

Trihalomethane-formation potential 

(μg/L)

5 1,066 223 448 -- 379 3

Specific absorbance (mg/L as DOC per cm-1

of DOC)

18 0.156 0.020 0.064 -- 0.089 

Appendix 1. Summary of descriptive statistics for selected surface-water sites in the J.B. Converse Lake watershed, Mobile Count

October 1990–June 1998—Continued

[NWIS, National Water Information System; ft3/s, cubic feet per second; μS/cm at 25 °C, microsiemens per centimeter at 25 degrees Celsius; mm, millimeter; mg/L, 

per 100 milliliters; --, missing data; <, less than; *, estimated; μg/L, microgram per liter; MBAS, methylene blue activated substances; nm, nanometer; cm-1, per cent

dissolved organic carbon; m, meter]


$VVHVVPHQWRI:DWHU4XDOLW\&RQGLWLRQVLQWKH-%&RQYHUVH/DNH:DWHUVKHG0RELOH&RXQW\$ODEDPD¥

Hamilton Creek (Big Creek Lake intake) near Semmes, 02480004 (site LHAM

1:,6

3$5$

0(7(5

&2'(

:$7(548$/,7<&2167,78(17 6$03/( 6,=(

'(6&5,37,9(67$7,67,&6 3(5&(17

0$;,080 0,1,080 0($1   

0

00078 Transparency (m) 20 3.55 0.88 2.22 3.54 2.68 00095 Specific conductance (μS/cm at 25 °C) 165 41 21 26 34 27 

00400 Field pH, whole water (standard unit) 140 6.9 5.4 6.2 6.7 6.4 00020 Air temperature (°C) 41 35.2 9.0 22.6 35.0 28.9 

00010 Water temperature (°C) 164 32.2 11.9 21.7 31.1 28.7 

00025 Air pressure (mm of Hg) 54 770 748 762 768 764 700300 Dissolved oxygen (mg/L) 163 10.7 0.1 7.6 10.4 9.1 00301 Dissolved oxygen (percent of saturation) 53 108 66 92 106 97 31625 Fecal coliform (col/100 mL) 42 220 <1 23* 110 18 31673 Fecal streptococcus (col/100 mL) 44 170 <1 12* 43 11 31633 Escherichia coli (col/100 mL) 20 180 <1 28* 170 15 

00900 Hardness, total (mg/L as CaCO3) 17 7 5 6 7 7 

00904 Noncarbonate hardness, dissolved 

(mg/L as CaCO3)

17 5 1 2 5 3 

00915 Calcium, dissolved (mg/L as Ca) 17 1.7 1.0 1.4 1.7 1.6 00925 Magnesium, dissolved (mg/L as Mg) 17 0.7 0.6 0.7 0.7 0.7 00930 Sodium, dissolved (mg/L as Na) 17 2.3 1.6 2.1 2.3 2.2 00935 Potassium, dissolved (mg/L as K) 17 0.9 0.5 0.7 0.9 0.8 00452 Carbonate, dissolved (mg/L as CO3) 46 0 -- -- -- -- 

00453 Bicarbonate, dissolved (mg/L as HCO3) 46 12 2 4.7 7.7 5 

39086 Alkalinity, dissolved (mg/L as CaCO3) 46 10 1 3.9 6 4 

00410 Acid-neutralizing capacity, field 

(mg/L as CaCO3)

47 11 2 4.8 7 5 

00945 Sulfate, dissolved (mg/L as SO4) 17 2 <0.2 1.6* 2.0 1.8 

Appendix 1. Summary of descriptive statistics for selected surface-water sites in the J.B. Converse Lake watershed, Mobile Coun

October 1990–June 1998—Continued

[NWIS, National Water Information System; ft3/s, cubic feet per second; μS/cm at 25 °C, microsiemens per centimeter at 25 degrees Celsius; mm, millimeter; mg/L, 

per 100 milliliters; --, missing data; <, less than; *, estimated; μg/L, microgram per liter; MBAS, methylene blue activated substances; nm, nanometer; cm-1, per cent

dissolved organic carbon; m, meter]
$

SSHQGL[HV

Hamilton Creek (Big Creek Lake intake) near Semmes, 02480004 (site LHAM

1:,6

3$5$

0(7(5

&2'(

:$7(548$/,7<&2167,78(17 6$03/( 6,=(

'(6&5,37,9(67$7,67,&6 3(5&(17

0$;,080 0,1,080 0($1   

0

00940 Chloride, dissolved (mg/L as Cl) 21 4 2.9 3.5 4.0 3.7 00950 Fluoride, dissolved (mg/L as F) 17 <0.1 <0.1 -- <0.1 <0.1 71870 Bromide, dissolved (mg/L as Br) 8 <0.05 <0.05 -- <0.05 <0.05 00955 Silica, dissolved (mg/L as SiO2) 17 4.3 2.0 3.1 4.3 3.6 70300 Total dissolved solids, residue at 180 °C 

(mg/L)

17 32 10 20 32 25 

70301 Total dissolved solids (mg/L) 15 18 14 16 18 17 80154 Suspended sediment concentration (mg/L)00615 Nitrite, total (mg/L as N) 31 0.01 <0.01 -- 0.01 <0.01 00613 Nitrite, dissolved (mg/L as N) 18 <0.01 <0.01 -- <0.01 <0.01 00620 Nitrate, total (mg/L as N) 3 0.13 0.12 -- -- -- 00630 Nitrite plus nitrate, total (mg/L as N) 27 0.2 <0.1 0.1* 0.2 0.2 00631 Nitrite plus nitrate, dissolved (mg/L as N) 33 0.2 <0.02 0.087* 0.19 0.15 00610 Ammonia, total (mg/L as N) 30 0.05 0.01 0.022 0.05 0.03 00608 Ammonia, dissolved (mg/L as N) 25 0.061 0.01 0.021 0.061 0.025 00605 Organic nitrogen, total (mg/L as N) 23 0.92 0.16 0.34 0.84 0.43 00600 Nitrogen, total (mg/L as N) 20 0.65 0.31 0.43 0.65 0.47 00625 Ammonia plus organic nitrogen, total 

(mg/L as N)

31 0.93 <0.20 0.33* 0.53 0.38 

00665 Phosphorus, total (mg/L as P) 30 0.04 <0.01 0.02* 0.04 0.02 00666 Phosphorus, dissolved (mg/L as P) 31 0.04 <0.01 0.01* 0.03 0.02 00671 Phosphorus, ortho (mg/L as P) 32 0.02 <0.01 0.007* 0.01 0.01 01020 Boron, dissolved (μg/L as B) 15 28 <20 13* *28 *17 

01045 Iron, total (μg/L as Fe) 17 1,400 180 398 1,400 440 3

01046 Iron, dissolved (μg/L as Fe) 17 660 40 200 660 250 1

01055 Manganese, total (μg/L as Mn) 17 340 <10 40* *340 33 *

01056 Manganese, dissolved (μg/L as Mn) 17 340 <10 26.4* *340 *10 

Appendix 1. Summary of descriptive statistics for selected surface-water sites in the J.B. Converse Lake watershed, Mobile Count

October 1990–June 1998—Continued

[NWIS, National Water Information System; ft3/s, cubic feet per second; μS/cm at 25 °C, microsiemens per centimeter at 25 degrees Celsius; mm, millimeter; mg/L, 

per 100 milliliters; --, missing data; <, less than; *, estimated; μg/L, microgram per liter; MBAS, methylene blue activated substances; nm, nanometer; cm-1, per cent

dissolved organic carbon; m, meter]


$VVHVVPHQWRI:DWHU4XDOLW\&RQGLWLRQVLQWKH-%&RQYHUVH/DNH:DWHUVKHG0RELOH&RXQW\$ODEDPD¥

Hamilton Creek (Big Creek Lake intake) near Semmes, 02480004 (site LHAM

1:,6

3$5$

0(7(5

&2'(

:$7(548$/,7<&2167,78(17 6$03/( 6,=(

'(6&5,37,9(67$7,67,&6 3(5&(17

0$;,080 0,1,080 0($1   

0

00680 Organic carbon, total (mg/L as C) 20 8.3 2 4.4 -- 5.3 00681 Organic carbon, dissolved (mg/L as C) 21 7.8 0.1 4.038 7.68 5.1 38260 Detergents as MBAS (mg/L) 20 0.4 <0.1 0.097* *0.400 <0.1 32240 Tannin and lignin (mg/L) 21 0.9 0.1 0.548 0.89 0.65 70953 Chlorophyll a, phytoplankton (μg/L) 17 9.7 -- 2.6* *9.7 *3.5 

70954 Chlorophyll b, phytoplankton (μg/L) 15 -- -- -- -- -- 

Ultraviolet absorbance at 254 nm 

(cm-1 as TOC)

18 0.241 0.099 0.162 -- 0.188 

Ultraviolet absorbance at 254 nm 

(cm-1 as DOC)

18 0.215 0.086 0.145 -- 0.174 

Trihalomethane-formation potential 

(μg/L)

5 729 293 438 -- 548 3

Specific absorbance (mg/L as DOC per cm-1

of DOC)

18 0.0870 0.0164 0.0421 -- 0.0551 

Appendix 1. Summary of descriptive statistics for selected surface-water sites in the J.B. Converse Lake watershed, Mobile Count

October 1990–June 1998—Continued

[NWIS, National Water Information System; ft3/s, cubic feet per second; μS/cm at 25 °C, microsiemens per centimeter at 25 degrees Celsius; mm, millimeter; mg/L, 

per 100 milliliters; --, missing data; <, less than; *, estimated; μg/L, microgram per liter; MBAS, methylene blue activated substances; nm, nanometer; cm-1, per cent

dissolved organic carbon; m, meter]
$SSHQGL[HV 

Appendix 2. Monthly mean load tables for selected surface-water sites in the J.B. Converse Lake watershed, 

Mobile County, Alabama, 1990–98

[kg/d, kilograms per day]

Big Creek at County Road 63 near Wilmer, 02479945 (site BIG)

Total nitrogen

0RQWK

'DLO\PHDQ

FRQVWLWXHQW

GLVFKDUJH

NJG

6WDQGDUG

HUURU

NJG

6WDQGDUG

HUURURI

SUHGLFWLRQ

NJG

0RQWK

'DLO\PHDQ

FRQVWLWXHQW

GLVFKDUJH

NJG

6WDQGDUG

HUURU

NJG

6WDQGDUG

HUURURI

SUHGLFWLRQ

NJG

:DWHU\HDU :DWHU\HDU

October 50.4 3.67 4.01 October 52.3 2.62 3.10

November 63.0 3.91 4.70 November 93.8 4.69 6.46

December 83.5 4.76 6.01 December 74.6 3.62 4.44

January 318 34.9 38.1 January 187 12.5 14.9

February 168 9.70 12.0 February 254 25.1 27.9

March 187 13.8 16.5 March 102 4.73 5.92

April 140 8.45 10.4 April 55.9 3.08 3.57

May 667 144 148 May 49.3 2.89 3.30

June 191 13.0 14.7 June 55.8 3.06 3.59

July 205 14.9 16.9 July 49.4 2.83 3.28

August 96.4 6.10 6.89 August 92.7 5.76 7.21

September 85.5 4.83 5.70 September 52.4 2.81 3.37

:DWHU\HDU :DWHU\HDU

October 37.7 2.61 2.88 October 73.3 5.28 6.59

November 215 20.3 22.7 November 80.5 5.39 6.42

December 181 16.0 18.3 December 85.4 5.62 6.54

January 174 16.3 18.7 January 91.1 5.82 6.92

February 127 6.97 8.39 February 68.5 4.06 4.80

March 173 11.0 12.8 March 94.1 5.40 6.62

April 118 6.18 7.61 April 86.2 4.64 5.86

May 242 49.0 52.8 May 47.4 2.79 3.29

June 143 10.0 11.8 June 58.5 3.24 3.94

July 99.5 6.33 7.24 July 178 15.2 17.0

August 105 7.15 8.14 August 51.3 3.21 3.70

September 76.4 4.92 5.68 September 38.8 2.91 3.17

:DWHU\HDU :DWHU\HDU

October 60.5 4.15 4.77 October 126 14.9 17.1

November 43.5 3.20 3.52 November 130 11.8 13.5

December 80.0 6.50 7.91 December 214 45.3 48.4

January 86.2 5.95 7.02 January 164 15.2 16.9

February 93.1 6.17 7.57 February 161 14.2 16.0

March 123 8.93 10.7 March 190 17.7 19.6

April 154 13.3 15.4 April 191 14.7 19.6

May 197 22.7 25.1 May 75.2 5.03 5.63

June 80.4 4.64 5.89 June 91.7 6.56 7.48

July 94.4 6.41 7.79 July 119 9.79 10.8

August 122 10.6 12.5 August 92.2 8.15 8.85

September 47.2 3.50 3.90 September 63.6 6.02 6.39

:DWHU\HDU :DWHU\HDU

October 49.1 4.99 5.23 October 110 15.6 16.4

November 56.1 5.87 6.17 November 170 26.3 27.8

December 69.6 7.25 7.76 December 138 20.4 21.1

January 109 11.1 11.8 January 257 40.6 41.9

February 122 12.1 13.1 February 155 23.1 23.8

March 95.6 9.39 10.2 March 192 30.0 31.3

April 83.7 8.31 9.00 April 115 17.9 18.4

May 80.2 8.31 9.00 May 71.8 11.9 12.1

June 182 20.7 22.0 June 65.4 11.3 11.6

July 206 25.4 26.7 July 107 19.4 19.8

August 103 13.3 13.8 August 86.4 16.3 16.7

September 58.6 8.03 8.26 September 722 364 372
 $VVHVVPHQWRI:DWHU4XDOLW\&RQGLWLRQVLQWKH-%&RQYHUVH/DNH:DWHUVKHG0RELOH&RXQW\$ODEDPD¥

Appendix 2. Monthly mean load tables for selected surface-water sites in the J.B. Converse Lake watershed, 

Mobile County, Alabama, 1990–98—Continued

[kg/d, kilograms per day]

Big Creek at County Road 63 near Wilmer, 02479945 (site BIG)

Total Kjeldahl nitrogen

0RQWK

'DLO\PHDQ

FRQVWLWXHQW

GLVFKDUJH

NJG

6WDQGDUG

HUURU

NJG

6WDQGDUG

HUURURI

SUHGLFWLRQ

NJG

0RQWK

'DLO\PHDQ

FRQVWLWXHQW

GLVFKDUJH

NJG

6WDQGDUG

HUURU

NJG

6WDQGDUG

HUURURI

SUHGLFWLRQ

NJG

:DWHU\HDU :DWHU\HDU

October 14.7 1.50 1.68 October 17.3 1.21 1.46

November 23.0 2.00 2.82 November 48.8 4.18 6.31

December 36.3 3.07 4.51 December 29.9 2.13 2.75

January 252 50.4 55.1 January 127 14.8 17.8

February 103 9.57 12.4 February 208 36.6 40.9

March 134 18.8 23.0 March 54.6 3.53 4.75

April 96.4 9.10 12.1 April 23.2 1.87 2.19

May 857 332 344 May 20.2 1.73 2.00

June 143 13.9 16.3 June 25.0 1.96 2.38

July 164 17.9 21.2 July 20.5 1.61 1.97

August 49.0 4.52 5.21 August 60.7 6.01 8.24

September 40.2 3.42 4.19 September 20.6 1.46 1.95

:DWHU\HDU :DWHU\HDU

October 11.2 0.994 1.14 October 39.3 4.72 6.78

November 166 26.2 29.7 November 38.9 3.87 5.21

December 129 21.0 24.8 December 40.5 3.86 4.86

January 127 23.2 27.1 January 46.9 4.48 5.80

February 73.1 5.77 7.25 February 29.8 2.46 3.11

March 124 12.4 14.7 March 53.8 4.71 6.19

April 76.3 5.86 7.72 April 51.1 4.18 5.69

May 302 119 129 May 20.5 1.66 2.15

June 116 12.8 15.7 June 28.7 2.27 3.09

July 60.5 5.56 6.63 July 151 20.6 23.6

August 64.1 6.39 7.64 August 21.4 1.74 2.25

September 37.3 3.42 4.27 September 12.1 1.11 1.27

:DWHU\HDU :DWHU\HDU

October 25.0 2.30 2.94 October 88.7 19.1 22.8

November 13.2 1.17 1.37 November 72.4 10.4 12.9

December 41.8 5.85 7.94 December 174 68.9 74.0

January 42.2 4.26 5.50 January 93.4 13.9 16.0

February 49.0 5.15 6.95 February 93.6 13.6 15.9

March 78.1 10.2 12.6 March 127 19.8 22.3

April 117 18.9 22.2 April 125 15.4 17.9

May 178 37.7 41.9 May 32.1 2.46 3.03

June 45.9 4.14 5.96 June 45.9 3.97 5.18

July 57.2 6.11 8.28 July 65.0 6.67 8.03

August 86.3 13.2 16.6 August 41.5 4.10 4.97

September 15.1 1.23 1.48 September 20.7 1.89 2.19

:DWHU\HDU :DWHU\HDU

October 12.9 1.18 1.34 October 42.5 6.12 7.09

November 15.4 1.46 1.69 November 76.7 14.9 16.9

December 22.5 2.21 2.81 December 48.9 6.98 7.85

January 42.8 4.43 5.35 January 117 22.3 23.9

February 52.1 5.45 6.63 February 56.7 8.12 8.86

March 39.5 4.17 5.36 March 87.4 16.9 18.7

April 34.6 3.49 4.41 April 40.2 6.02 6.44

May 34.2 3.70 4.73 May 20.7 3.34 3.55

June 105 14.2 16.1 June 17.9 3.02 3.20

July 119 17.5 19.5 July 37.1 4.67 7.03

August 40.1 5.07 5.69 August 25.7 4.67 5.04

September 15.4 1.88 2.06 September 612 492 504
$SSHQGL[HV 

Appendix 2. Monthly mean load tables for selected surface-water sites in the J.B. Converse Lake watershed, 

Mobile County, Alabama, 1990–98—Continued

[kg/d, kilograms per day]

Big Creek at County Road 63 near Wilmer, 02479945 (site BIG)

Total inorganic nitrogen

0RQWK

'DLO\PHDQ

FRQVWLWXHQW

GLVFKDUJH

NJG

6WDQGDUG

HUURU

NJG

6WDQGDUG

HUURURI

SUHGLFWLRQ

NJG

0RQWK

'DLO\PHDQ

FRQVWLWXHQW

GLVFKDUJH

NJG

6WDQGDUG

HUURU

NJG

6WDQGDUG

HUURURI

SUHGLFWLRQ

NJG

:DWHU\HDU :DWHU\HDU

October 51.4 13.3 14.9 October 41.7 7.32 9.17

November 57.2 13.4 15.6 November 52.2 8.85 11.6

December 66.0 14.3 17.0 December 52.4 9.39 11.7

January 115 32.0 36.1 January 77.5 15.3 18.8

February 92.7 18.6 23.0 February 86.6 21.3 24.8

March 90.3 18.7 22.7 March 60.0 10.1 13.0

April 74.3 15.3 18.6 April 44.1 8.96 10.8

May 118 45.8 48.5 May 38.4 8.24 9.68

June 71.5 16.8 19.5 June 36.6 7.17 8.72

July 66.9 16.3 18.8 July 32.7 6.61 7.91

August 48.1 11.0 12.8 August 37.8 6.92 8.71

September 46.3 9.29 11.2 September 32.6 5.81 7.31

:DWHU\HDU :DWHU\HDU

October 31.1 7.01 8.13 October 31.6 6.52 7.89

November 58.9 15.4 17.7 November 35.5 7.71 9.16

December 58.9 13.7 16.0 December 39.3 8.60 10.1

January 60.3 13.3 15.8 January 42.2 8.96 10.7

February 57.8 11.0 13.7 February 38.8 8.03 9.73

March 63.0 12.7 15.4 March 42.0 8.27 10.1

April 49.6 8.86 11.2 April 37.7 7.27 9.00

May 47.7 11.9 13.8 May 28.1 6.38 7.42

June 42.8 8.86 10.8 June 27.7 5.53 6.70

July 35.4 7.66 9.02 July 38.4 9.79 11.2

August 34.7 7.94 9.23 August 24.4 4.96 5.94

September 31.4 6.70 7.95 September 22.9 5.25 6.10

:DWHU\HDU :DWHU\HDU

October    October   

November    November   

December    December   

January    January   

February    February   

March    March   

April    April   

May    May   

June    June   

July    July   

August    August   

September    September   

:DWHU\HDU :DWHU\HDU

October    October   

November    November   

December    December   

January    January   

February    February   

March    March   

April    April   

May    May   

June    June   

July    July   

August    August   

September    September   
 $VVHVVPHQWRI:DWHU4XDOLW\&RQGLWLRQVLQWKH-%&RQYHUVH/DNH:DWHUVKHG0RELOH&RXQW\$ODEDPD¥

Appendix 2. Monthly mean load tables for selected surface-water sites in the J.B. Converse Lake watershed, 

Mobile County, Alabama, 1990–98—Continued

[kg/d, kilograms per day]

Big Creek at County Road 63 near Wilmer, 02479945 (site BIG)

Total phosphorus

0RQWK

'DLO\PHDQ

FRQVWLWXHQW

GLVFKDUJH

NJG

6WDQGDUG

HUURU

NJG

6WDQGDUG

HUURURI

SUHGLFWLRQ

NJG

0RQWK

'DLO\PHDQ

FRQVWLWXHQW

GLVFKDUJH

NJG

6WDQGDUG

HUURU

NJG

6WDQGDUG

HUURURI

SUHGLFWLRQ

NJG

:DWHU\HDU :DWHU\HDU

October 0.975 0.260 0.314 October 1.24 .290 .358

November 1.54 .384 .563 November 3.12 .825 1.23

December 2.38 .603 .889 December 2.39 .537 .714

January 10.9 3.88 4.79 January 7.22 2.03 2.68

February 5.23 1.37 1.86 February 9.41 2.86 3.78

March 5.50 1.53 2.17 March 3.11 .689 .925

April 3.56 .937 1.30 April 1.27 .349 .415

May 17.0 7.91 9.24 May .983 .276 .325

June 4.72 1.45 1.72 June 1.15 .291 .365

July 5.23 1.81 2.15 July .997 .245 .313

August 2.29 .060 .732 August 2.55 .762 1.06

September 2.19 .550 .709 September 1.32 .290 .404

:DWHU\HDU :DWHU\HDU

October 0.896 0.212 0.265 October 2.67 .741 1.20

November 9.05 3.44 4.17 November 3.20 .782 1.15

December 7.79 2.50 3.31 December 3.62 .828 1.17

January 7.36 2.13 3.03 January 3.85 .847 1.26

February 4.99 1.06 1.47 February 2.56 .552 .782

March 6.49 1.52 2.04 March 3.53 .739 1.13

April 3.82 .825 1.16 April 2.86 .615 .930

May 7.32 3.09 4.40 May 1.20 .290 .396

June 4.35 1.31 1.71 June 1.54 .358 .509

July 2.87 .740 .937 July 6.03 2.24 2.69

August 3.27 .911 1.14 August 1.38 .324 .439

September 2.43 .590 .791 September 1.00 .238 .298

:DWHU\HDU :DWHU\HDU

October 2.15 0.524 0.727 October 5.22 2.29 3.07

November 1.48 .349 .449 November 6.10 2.19 2.79

December 3.51 .981 1.58 December 10.3 4.95 6.69

January 3.84 .920 1.35 January 8.22 2.67 3.39

February 3.97 .925 1.45 February 7.57 2.26 3.01

March 5.03 1.25 1.87 March 8.15 2.51 3.20

April 5.83 1.68 2.37 April 7.59 2.29 2.85

May 7.08 2.55 3.33 May 2.33 .615 .758

June 2.45 .642 .939 June 2.90 .845 1.08

July 3.03 .948 1.28 July 4.02 1.39 1.66

August 4.23 1.61 2.11 August 3.12 1.01 1.21

September 1.40 .355 .443 September 2.12 .620 .740

:DWHU\HDU :DWHU\HDU

October 1.63 0.469 0.546 October 4.66 1.92 2.30

November 2.16 .630 .753 November 8.08 3.65 4.39

December 3.02 .897 1.15 December 6.65 2.50 2.90

January 5.13 1.57 1.94 January 12.9 5.38 6.11

February 5.48 1.64 2.06 February 6.99 2.41 2.81

March 3.77 1.08 1.44 March 8.03 2.96 3.61

April 2.87 .834 1.10 April 4.06 1.34 1.56

May 2.51 .769 1.01 May 2.05 .694 .801

June 6.35 2.50 2.89 June 1.72 .601 .693

July 7.33 3.19 3.59 July 3.32 1.30 1.49

August 3.49 1.26 1.45 August 2.66 1.04 1.21

September 1.82 .594 .683 September 22.5 19.6 23.3
$SSHQGL[HV 

Appendix 2. Monthly mean load tables for selected surface-water sites in the J.B. Converse Lake watershed, 

Mobile County, Alabama, 1990–98—Continued

[kg/d, kilograms per day]

Juniper Creek at Glenwood Road near Fairview, 02479948 (site JUN)

Total nitrogen

0RQWK

'DLO\PHDQ

FRQVWLWXHQW

GLVFKDUJH

NJG

6WDQGDUG

HUURU

NJG

6WDQGDUG

HUURURI

SUHGLFWLRQ

NJG

0RQWK

'DLO\PHDQ

FRQVWLWXHQW

GLVFKDUJH

NJG

6WDQGDUG

HUURU

NJG

6WDQGDUG

HUURURI

SUHGLFWLRQ

NJG

:DWHU\HDU :DWHU\HDU

October 19.1 3.20 3.28 October 22.4 2.00 2.18

November 20.6 2.66 2.81 November 25.8 2.62 2.87

December 22.8 2.28 2.49 December 23.4 2.36 2.54

January 47.0 6.14 6.50 January 36.4 4.10 4.39

February 32.0 2.22 2.65 February 49.9 7.10 7.45

March 39.4 3.01 3.46 March 38.1 3.48 3.80

April 36.7 2.72 3.16 April 27.3 2.42 2.64

May 72.8 11.3 11.7 May 21.3 2.18 2.33

June 49.2 4.17 4.62 June 24.7 2.36 2.59

July 43.0 3.91 4.27 July 24.8 2.76 2.94

August 28.4 2.56 2.80 August 21.3 2.58 2.73

September 26.8 2.38 2.62 September 18.6 2.52 2.62

Juniper Creek at Glenwood Road near Fairview, 02479948 (site JUN)

Total Kjeldahl nitrogen

0RQWK

'DLO\PHDQ

FRQVWLWXHQW

GLVFKDUJH

NJG

6WDQGDUG

HUURU

NJG

6WDQGDUG

HUURURI

SUHGLFWLRQ

NJG

0RQWK

'DLO\PHDQ

FRQVWLWXHQW

GLVFKDUJH

NJG

6WDQGDUG

HUURU

NJG

6WDQGDUG

HUURURI

SUHGLFWLRQ

NJG

:DWHU\HDU :DWHU\HDU

October 6.54 1.62 1.74 October 6.61 1.40 1.53

November 7.45 1.57 1.86 November 8.87 2.08 2.43

December 8.47 1.58 1.91 December 6.84 1.41 1.57

January 22.4 6.82 7.38 January 14.6 3.23 3.69

February 14.2 2.38 3.00 February 21.9 5.89 6.48

March 19.2 4.20 4.78 March 15.3 2.67 3.10

April 18.5 3.57 4.26 April 9.23 1.71 1.93

May 44.4 14.6 15.3 May 6.52 1.36 1.50

June 27.0 5.85 6.46 June 8.62 1.84 2.13

July 21.6 4.90 5.40 July 8.11 2.08 2.25

August 10.7 2.31 2.54 August 6.28 1.73 1.86

September 9.50 2.02 2.27 September 4.72 1.46 1.54
 $VVHVVPHQWRI:DWHU4XDOLW\&RQGLWLRQVLQWKH-%&RQYHUVH/DNH:DWHUVKHG0RELOH&RXQW\$ODEDPD¥

Appendix 2. Monthly mean load tables for selected surface-water sites in the J.B. Converse Lake watershed, 

Mobile County, Alabama, 1990–98—Continued

[kg/d, kilograms per day]

Juniper Creek at Glenwood Road near Fairview, 02479948 (site JUN)

Total inorganic nitrogen

0RQWK

'DLO\PHDQ

FRQVWLWXHQW

GLVFKDUJH

NJG

6WDQGDUG

HUURU

NJG

6WDQGDUG

HUURURI

SUHGLFWLRQ

NJG

0RQWK

'DLO\PHDQ

FRQVWLWXHQW

GLVFKDUJH

NJG

6WDQGDUG

HUURU

NJG

6WDQGDUG

HUURURI

SUHGLFWLRQ

NJG

:DWHU\HDU :DWHU\HDU

October 9.70 0.665 0.711 October 16.0 0.912 1.00

November 10.9 .626 .689 November 17.0 1.01 1.11

December 12.5 .657 .733 December 17.1 .983 1.08

January 18.5 1.39 1.48 January 20.4 1.13 1.25

February 16.8 .817 .939 February 23.5 1.62 1.74

March 19.2 .970 1.09 March 20.5 1.02 1.15

April 19.1 1.03 1.15 April 17.1 .896 1.00

May 26.5 2.75 2.83 May 14.4 .863 .940

June 21.7 1.34 1.45 June 13.9 .784 .866

July 20.2 1.30 1.40 July 12.8 .830 .894

August 17.1 1.04 1.13 August 11.2 .777 .830

September 16.8 .971 1.07 September 9.98 .802 .843

Juniper Creek at Glenwood Road near Fairview, 02479948 (site JUN)

Total phosphorus

0RQWK

'DLO\PHDQ

FRQVWLWXHQW

GLVFKDUJH

NJG

6WDQGDUG

HUURU

NJG

6WDQGDUG

HUURURI

SUHGLFWLRQ

NJG

0RQWK

'DLO\PHDQ

FRQVWLWXHQW

GLVFKDUJH

NJG

6WDQGDUG

HUURU

NJG

6WDQGDUG

HUURURI

SUHGLFWLRQ

NJG

:DWHU\HDU :DWHU\HDU

October 0.220 0.134 0.155 October 1.31 0.585 0.713

November .053 .284 .489 November 3.91 2.84 3.95

December .770 .384 .622 December 2.00 .970 1.24

January 13.1 14.7 18.4 January 6.56 4.65 6.12

February 1.33 .657 1.15 February 19.5 21.9 28.3

March 3.00 2.21 3.59 March 2.42 1.21 1.65

April 1.12 .600 .902 April .640 .339 .398

May 9.67 9.88 11.7 May .313 .179 .209

June 1.60 .934 1.13 June .586 .304 .451

July 1.56 .932 1.13 July .628 .344 .426

August .950 .481 .615 August .670 .390 .492

September 1.40 .719 .926 September .696 .438 .506
$SSHQGL[HV 

Appendix 2. Monthly mean load tables for selected surface-water sites in the J.B. Converse Lake watershed, 

Mobile County, Alabama, 1990–98—Continued

[kg/d, kilograms per day]

Collins Creek at Glenwood Road near Fairview, 02479950 (site COL)

Total nitrogen

0RQWK

'DLO\PHDQ

FRQVWLWXHQW

GLVFKDUJH

NJG

6WDQGDUG

HUURU

NJG

6WDQGDUG

HUURURI

SUHGLFWLRQ

NJG

0RQWK

'DLO\PHDQ

FRQVWLWXHQW

GLVFKDUJH

NJG

6WDQGDUG

HUURU

NJG

6WDQGDUG

HUURURI

SUHGLFWLRQ

NJG

:DWHU\HDU :DWHU\HDU

October 10.0 1.25 1.30 October 12.8 1.10 1.18

November 11.1 1.16 1.22 November 15.0 1.24 1.36

December 15.1 1.67 1.76 December 12.6 1.09 1.17

January 41.1 7.13 7.48 January 18.2 1.65 1.80

February 19.5 1.39 1.62 February 35.2 5.83 6.14

March 19.0 1.23 1.47 March 17.5 1.41 1.54

April 19.1 1.20 1.41 April 12.2 .91 1.00

May 55.6 11.4 11.8 May 10.0 1.09 1.14

June 28.4 1.84 2.09 June 14.2 1.20 1.31

July 25.7 1.74 1.96 July 12.6 1.24 1.32

August 17.4 1.21 1.34 August 9.95 1.00 1.06

September 15.7 1.14 1.26 September 9.51 1.18 1.22

Collins Creek at Glenwood Road near Fairview, 02479950 (site COL)

Total Kjeldahl nitrogen

0RQWK

'DLO\PHDQ

FRQVWLWXHQW

GLVFKDUJH

NJG

6WDQGDUG

HUURU

NJG

6WDQGDUG

HUURURI

SUHGLFWLRQ

NJG

0RQWK

'DLO\PHDQ

FRQVWLWXHQW

GLVFKDUJH

NJG

6WDQGDUG

HUURU

NJG

6WDQGDUG

HUURURI

SUHGLFWLRQ

NJG

:DWHU\HDU :DWHU\HDU

October 5.02 0.736 0.780 October 6.29 0.773 0.836

November 5.43 .663 .738 November 7.57 .890 1.01

December 7.75 .930 1.03 December 5.83 .687 .749

January 34.6 13.0 13.5 January 10.1 1.27 1.46

February 11.7 1.21 1.54 February 28.6 9.40 9.97

March 12.1 1.29 1.60 March 10.4 1.12 1.28

April 12.6 1.23 1.49 April 7.00 .718 .804

May 59.8 24.0 24.8 May 5.95 .783 .842

June 21.2 2.35 2.63 June 9.48 1.39 1.50

July 18.6 2.11 2.35 July 8.11 1.38 1.45

August 10.5 1.14 1.26 August 5.85 1.00 1.04

September 8.77 .953 1.07 September 5.23 1.09 1.12
 $VVHVVPHQWRI:DWHU4XDOLW\&RQGLWLRQVLQWKH-%&RQYHUVH/DNH:DWHUVKHG0RELOH&RXQW\$ODEDPD¥

Appendix 2. Monthly mean load tables for selected surface-water sites in the J.B. Converse Lake watershed, 

Mobile County, Alabama, 1990–98—Continued

[kg/d, kilograms per day]

Collins Creek at Glenwood Road near Fairview, 02479950 (site COL)

Total inorganic nitrogen

0RQWK

'DLO\PHDQ

FRQVWLWXHQW

GLVFKDUJH

NJG

6WDQGDUG

HUURU

NJG

6WDQGDUG

HUURURI

SUHGLFWLRQ

NJG

0RQWK

'DLO\PHDQ

FRQVWLWXHQW

GLVFKDUJH

NJG

6WDQGDUG

HUURU

NJG

6WDQGDUG

HUURURI

SUHGLFWLRQ

NJG

:DWHU\HDU :DWHU\HDU

October 3.88 0.326 0.349 October 5.23 0.392 0.425

November 4.41 .315 .348 November 6.05 .426 .471

December 6.09 .424 .468 December 5.52 .391 .429

January 7.97 .596 .649 January 6.68 .447 .498

February 6.34 .370 .428 February 7.89 .635 .689

March 5.54 .335 .381 March 6.24 .408 .454

April 5.41 .341 .387 April 4.32 .267 .302

May 8.08 .670 .718 May 3.19 .244 .265

June 7.40 .516 .569 June 4.66 .378 .409

July 7.21 .512 .562 July 4.43 .413 .438

August 6.09 .418 .460 August 3.68 .331 .353

September 5.80 .394 .438 September 3.93 .455 .473

Collins Creek at Glenwood Road near Fairview, 02479950 (site COL)

Total phosphorus

0RQWK

'DLO\PHDQ

FRQVWLWXHQW

GLVFKDUJH

NJG

6WDQGDUG

HUURU

NJG

6WDQGDUG

HUURURI

SUHGLFWLRQ

NJG

0RQWK

'DLO\PHDQ

FRQVWLWXHQW

GLVFKDUJH

NJG

6WDQGDUG

HUURU

NJG

6WDQGDUG

HUURURI

SUHGLFWLRQ

NJG

:DWHU\HDU :DWHU\HDU

October 0.248 0.092 0.099 October 0.515 0.159 0.175

November .344 .107 .121 November .789 .232 .270

December .589 .176 .200 December .712 .208 .232

January 1.37 .623 .671 January 1.25 .388 .452

February .820 .206 .263 February 2.04 .811 .891

March .744 .203 .256 March 1.08 .306 .351

April .636 .163 .200 April .610 .156 .179

May 1.47 .540 .597 May .419 .127 .141

June .865 .253 .286 June .629 .214 .236

July .778 .234 .263 July .547 .211 .226

August .523 .150 .167 August .463 .171 .184

September .542 .153 .173 September .503 .240 .251
$SSHQGL[HV 

Appendix 2. Monthly mean load tables for selected 

surface-water sites in the J.B. Converse Lake watershed, 

Mobile County, Alabama, 1990–98—Continued

[kg/d, kilograms per day]

Long Branch near Wilmer, 02479955 

(site LON)

Total nitrogen

0RQWK

'DLO\PHDQ

FRQVWLWXHQW

GLVFKDUJH

NJG

6WDQGDUG

HUURU

NJG

6WDQGDUG

HUURURI

SUHGLFWLRQ

NJG

:DWHU\HDU

October 1.51 0.487 0.499

November 5.35 1.01 1.06

December 9.61 2.24 2.32

January 34.8 37.1 37.3

February 19.6 3.35 3.61

March 12.9 6.25 6.41

April 13.6 2.13 2.31

May 19.9 7.82 8.16

June 22.0 2.40 2.77

July 19.6 3.23 3.47

August 13.2 2.25 2.40

September 6.41 1.52 1.58

Long Branch near Wilmer, 02479955 

(site LON)

Total Kjeldahl nitrogen

0RQWK

'DLO\PHDQ

FRQVWLWXHQW

GLVFKDUJH

NJG

6WDQGDUG

HUURU

NJG

6WDQGDUG

HUURURI

SUHGLFWLRQ

NJG

:DWHU\HDU

October 1.59 0.558 0.591

November 1.87 .520 .571

December 2.09 .608 .660

January 11.56 6.07 6.32

February 6.18 1.61 1.84

March 6.16 1.54 1.81

April 6.18 1.57 1.85

May 19.78 9.36 9.75

June 9.87 2.64 2.92

July 10.34 2.85 3.21

August 7.34 2.20 2.39

September 5.72 2.57 2.67
 $VVHVVPHQWRI:DWHU4XDOLW\&RQGLWLRQVLQWKH-%&RQYHUVH/DNH:DWHUVKHG0RELOH&RXQW\$ODEDPD¥

Appendix 2. Monthly mean load tables for selected 

surface-water sites in the J.B. Converse Lake watershed, 

Mobile County, Alabama, 1990–98—Continued

[kg/d, kilograms per day]

Long Branch near Wilmer, 02479955 

(site LON)

Total inorganic nitrogen

0RQWK

'DLO\PHDQ

FRQVWLWXHQW

GLVFKDUJH

NJG

6WDQGDUG

HUURU

NJG

6WDQGDUG

HUURURI

SUHGLFWLRQ

NJG

:DWHU\HDU

October 2.58 0.282 0.299

November 3.68 .323 .354

December 5.15 .486 .525

January 37.0 7.08 7.37

February 17.0 1.45 1.65

March 15.9 1.34 1.58

April 11.6 .956 1.10

May 30.0 4.95 5.16

June 9.84 .861 .947

July 8.53 .789 .883

August 5.37 .536 .578

September 4.75 .720 .744

Long Branch near Wilmer, 02479955 (site LON)

Total phosphorus

0RQWK

'DLO\PHDQ

FRQVWLWXHQW

GLVFKDUJH

NJG

6WDQGDUG

HUURU

NJG

6WDQGDUG

HUURURI

SUHGLFWLRQ

NJG

:DWHU\HDU

October 0.058 0.051 0.052

November .116 .168 .072

December .148 .068 .074

January .223 .118 .127

February .234 .093 .104

March .214 .078 .089

April .202 .075 .086

May .306 .172 .182

June .308 .125 .139

July .343 .127 .143

August .361 .158 .173

September .313 .220 .228
$SSHQGL[HV 

Appendix 2. Monthly mean load tables for selected 

surface-water sites in the J.B. Converse Lake watershed, 

Mobile County, Alabama, 1990–98—Continued

[kg/d, kilograms per day]

Boggy Branch near Wilmer, 02479960 

(site BOG)

Total nitrogen

0RQWK

'DLO\PHDQ

FRQVWLWXHQW

GLVFKDUJH

NJG

6WDQGDUG

HUURU

NJG

6WDQGDUG

HUURURI

SUHGLFWLRQ

NJG

:DWHU\HDU

October 2.28 0.386 0.441

November 6.24 3.65 3.93

December 6.90 2.50 2.73

January -128 301 303

February 8.42 2.33 3.15

March -2.90 23.0 23.9

April 25.5 11.3 11.7

May -77.2 201 204

June 22.0 6.17 6.61

July -4.91 28.0 29.0

August 6.05 .798 .914

September 2.95 .915 .951

Boggy Branch near Wilmer, 02479960 

(site BOG)

Total Kjeldahl nitrogen

0RQWK

'DLO\PHDQ

FRQVWLWXHQW

GLVFKDUJH

NJG

6WDQGDUG

HUURU

NJG

6WDQGDUG

HUURURI

SUHGLFWLRQ

NJG

:DWHU\HDU

October 1.96 0.401 0.466

November 3.29 1.12 1.37

December 3.30 .765 .917

January 22.6 9.54 10.1

February 9.67 1.97 2.32

March 13.0 2.55 3.00

April 20.3 4.02 4.64

May 60.5 17.9 18.8

June 16.3 2.89 3.35

July 22.4 6.40 7.15

August 4.57 .808 .896

September 1.72 .453 .487
 $VVHVVPHQWRI:DWHU4XDOLW\&RQGLWLRQVLQWKH-%&RQYHUVH/DNH:DWHUVKHG0RELOH&RXQW\$ODEDPD¥

Appendix 2. Monthly mean load tables for selected 

surface-water sites in the J.B. Converse Lake watershed, 

Mobile County, Alabama, 1990–98—Continued

[kg/d, kilograms per day]

Boggy Branch near Wilmer, 02479960 

(site BOG)

Total inorganic nitrogen

0RQWK

'DLO\PHDQ

FRQVWLWXHQW

GLVFKDUJH

NJG

6WDQGDUG

HUURU

NJG

6WDQGDUG

HUURURI

SUHGLFWLRQ

NJG

:DWHU\HDU

October 0.573 0.093 0.109

November 1.41 .361 .442

December 1.91 .341 .406

January 12.9 4.34 4.56

February 4.51 .713 .834

March 4.76 .773 .912

April 4.54 .698 .802

May 10.8 2.54 2.68

June 2.93 .414 .477

July 4.58 1.01 1.12

August 1.68 .244 .269

September 1.20 .259 .280

Boggy Branch near Wilmer, 02479960 

(site BOG)

Total phosphorus

0RQWK

'DLO\PHDQ

FRQVWLWXHQW

GLVFKDUJH

NJG

6WDQGDUG

HUURU

NJG

6WDQGDUG

HUURURI

SUHGLFWLRQ

NJG

:DWHU\HDU

October 0.124 0.023 0.025

November .139 .021 .023

December .165 .024 .027

January .230 .052 .054

February .232 .034 .037

March .243 .034 .038

April .250 .038 .042

May .290 .068 .070

June .239 .037 .041

July .239 .037 .040

August .215 .036 .039

September .196 .052 .053
$SSHQGL[HV 

Appendix 2. Monthly mean load tables for selected surface-water sites in the J.B. Converse Lake watershed, 

Mobile County, Alabama, 1990–98—Continued

[kg/d, kilograms per day]

Crooked Creek near Fairview, 02479980 (site CRO)

Total nitrogen

0RQWK

'DLO\PHDQ

FRQVWLWXHQW

GLVFKDUJH

NJG

6WDQGDUG

HUURU

NJG

6WDQGDUG

HUURURI

SUHGLFWLRQ

NJG

0RQWK

'DLO\PHDQ

FRQVWLWXHQW

GLVFKDUJH

NJG

6WDQGDUG

HUURU

NJG

6WDQGDUG

HUURURI

SUHGLFWLRQ

NJG

:DWHU\HDU :DWHU\HDU

October 15.0 1.64 1.81 October 18.8 1.49 1.76

November 19.3 1.94 2.31 November 30.2 3.18 3.91

December 26.8 3.08 3.65 December 20.9 1.70 2.01

January 80.2 27.4 28.1 January 42.4 6.87 7.66

February 38.4 4.62 5.35 February 51.8 10.3 11.1

March 40.4 5.71 6.40 March 31.6 2.51 3.22

April 46.2 6.01 6.77 April 18.0 1.46 1.72

May 90.1 20.2 21.0 May 18.8 1.50 1.95

June 40.9 4.41 4.98 June 25.9 2.13 2.68

July 45.9 5.38 6.08 July 19.4 1.63 1.94

August 30.0 2.93 3.33 August 18.2 1.55 1.84

September 23.7 2.03 2.41 September 20.1 1.81 2.31

:DWHU\HDU :DWHU\HDU

October 14.7 1.41 1.59 October 23.9 3.33 4.05

November 42.9 5.76 6.54 November 19.4 2.15 2.39

December 37.4 6.04 6.87 December 19.2 2.15 2.38

January 42.9 12.9 13.5 January 28.1 3.96 4.65

February 29.7 2.77 3.23 February 15.6 1.68 1.87

March 51.0 7.98 8.84 March 22.7 2.06 2.49

April 32.8 2.76 3.29 April 21.6 1.82 2.26

May 51.6 13.0 13.8 May 16.2 1.51 1.75

June 36.8 3.58 4.18 June 30.4 5.29 6.25

July 35.2 3.68 1.46 July 54.1 8.89 9.91

August 29.5 3.13 3.50 August 21.6 2.18 2.50

September 30.9 3.57 3.97 September 15.4 1.75 1.92

:DWHU\HDU :DWHU\HDU

October 20.7 2.39 2.73 October 49.1 12.4 13.3

November 15.6 1.91 2.14 November 38.8 6.54 7.34

December 22.7 3.40 4.04 December 49.5 23.5 24.0

January 29.4 4.07 4.71 January 42.9 7.11 7.82

February 19.5 2.06 2.36 February 38.6 5.64 6.39

March 32.4 4.12 4.87 March 42.3 6.77 7.55

April 37.6 4.91 5.78 April 50.8 7.41 8.29

May 63.8 27.4 28.1 May 24.0 1.97 2.31

June 32.5 3.05 3.85 June 25.2 2.12 2.54

July 27.5 2.87 3.06 July 35.7 3.73 4.30

August 55.3 13.3 14.3 August 42.3 5.18 5.84

September 22.1 2.46 2.72 September 28.1 3.35 3.73

:DWHU\HDU :DWHU\HDU

October 20.4 2.50 2.71 October 39.7 7.84 8.50

November 17.3 2.27 2.43 November 58.6 17.2 17.9

December 29.8 4.64 5.21 December 37.7 6.82 7.31

January 33.3 4.91 5.47 January 95.6 34.3 34.9

February 35.9 4.71 5.32 February 45.6 7.76 8.27

March 32.1 4.73 5.35 March 55.5 18.4 18.9

April 25.4 2.69 3.23 April 37.3 5.55 6.00

May 42.5 10.9 11.6 May 26.8 3.90 4.24

June 75.0 18.5 19.4 June 22.6 3.47 3.73

July 137 50.1 50.9 July 47.3 9.22 9.79

August 54.4 7.79 8.32 August 30.3 5.33 5.65

September 30.4 4.18 4.46 September 80.9 43.8 44.3
 $VVHVVPHQWRI:DWHU4XDOLW\&RQGLWLRQVLQWKH-%&RQYHUVH/DNH:DWHUVKHG0RELOH&RXQW\$ODEDPD¥

Appendix 2. Monthly mean load tables for selected surface-water sites in the J.B. Converse Lake watershed, 

Mobile County, Alabama, 1990–98—Continued

[kg/d, kilograms per day]

Crooked Creek near Fairview, 02479980 (site CRO)

Total Kjeldahl nitrogen

0RQWK

'DLO\PHDQ

FRQVWLWXHQW

GLVFKDUJH

NJG

6WDQGDUG

HUURU

NJG

6WDQGDUG

HUURURI

SUHGLFWLRQ

NJG

0RQWK

'DLO\PHDQ

FRQVWLWXHQW

GLVFKDUJH

NJG

6WDQGDUG

HUURU

NJG

6WDQGDUG

HUURURI

SUHGLFWLRQ

NJG

:DWHU\HDU :DWHU\HDU

October 5.72 1.11 1.23 October 6.58 .870 1.07

November 7.77 1.39 1.83 November 12.7 2.86 3.73

December 12.6 2.91 3.63 December 6.95 .940 1.66

January 57.5 42.7 43.8 January 22.7 9.26 10.4

February 23.3 6.29 4.52 February 33.5 16.4 17.7

March 28.3 9.24 10.5 March 17.4 2.90 3.99

April 38.0 10.2 11.7 April 8.76 1.19 1.46

May 92.9 45.5 47.5 May 10.8 1.47 2.23

June 29.1 5.41 6.43 June 15.3 2.24 3.07

July 33.2 7.14 8.50 July 9.34 1.32 1.66

August 15.3 2.51 2.97 August 7.67 1.07 1.36

September 10.0 1.45 1.82 September 7.31 1.22 1.77

:DWHU\HDU :DWHU\HDU

October 4.47 0.669 0.796 October 9.09 2.83 3.73

November 17.7 4.79 5.64 November 5.24 .879 1.04

December 16.1 6.91 7.95 December 5.18 .883 1.04

January 17.9 12.6 13.2 January 11.3 4.09 5.01

February 11.7 1.85 2.27 February 4.80 .778 .917

March 33.2 12.9 14.2 March 9.08 1.38 1.83

April 16.9 2.53 3.17 April 9.70 1.39 1.91

May 37.7 24.4 25.9 May 6.95 1.07 1.31

June 20.5 3.53 4.35 June 20.4 9.14 11.0

July 17.7 3.17 3.74 July 35.6 13.5 15.3

August 12.2 2.11 2.47 August 8.02 1.26 1.59

September 11.2 2.10 2.46 September 4.50 .763 .880

:DWHU\HDU :DWHU\HDU

October 6.02 1.06 1.38 October 22.0 16.6 14.7

November 3.91 .692 .876 November 13.3 5.02 5.93

December 7.52 2.47 3.19 December 14.6 11.2 11.7

January 10.9 3.17 3.89 January 16.0 5.84 6.57

February 6.05 .982 1.25 February 15.1 5.16 6.01

March 15.4 4.66 5.64 March 21.3 8.74 9.80

April 21.4 6.81 8.10 April 27.8 10.3 11.6

May 40.7 29.6 30.7 May 9.62 1.37 1.67

June 17.0 3.36 4.61 June 10.4 1.46 1.87

July 11.1 1.73 2.11 July 15.2 2.51 3.13

August 30.7 19.3 20.8 August 17.4 3.51 4.38

September September 8.34 1.36 1.71

:DWHU\HDU :DWHU\HDU

October 4.90 0.790 0.925 October 13.3 5.43 6.19

November 3.76 .662 .756 November 21.4 13.3 13.9

December 8.97 2.66 3.23 December 11.0 3.69 4.19

January 10.9 3.16 3.75 January 37.9 24.5 25.1

February 13.07 3.14 3.77 February 16.3 4.92 5.46

March 14.0 4.47 5.22 March 23.3 15.5 16.0

April 10.8 2.14 2.82 April 16.1 4.18 4.73

May 27.1 16.0 17.2 May 11.2 2.74 3.17

June 49.5 26.3 27.7 June 8.88 2.19 2.51

July 85.0 58.8 59.9 July 22.4 7.57 8.37

August 21.5 4.44 5.04 August 10.5 2.72 3.09

September 8.60 1.56 1.78 September 27.2 18.6 19.2
$SSHQGL[HV 

Appendix 2. Monthly mean load tables for selected surface-water sites in the J.B. Converse Lake watershed, 

Mobile County, Alabama, 1990–98—Continued

[kg/d, kilograms per day]

Crooked Creek near Fairview, 02479980 (site CRO)

Total inorganic nitrogen

0RQWK

'DLO\PHDQ

FRQVWLWXHQW

GLVFKDUJH

NJG

6WDQGDUG

HUURU

NJG

6WDQGDUG

HUURURI

SUHGLFWLRQ

NJG

0RQWK

'DLO\PHDQ

FRQVWLWXHQW

GLVFKDUJH

NJG

6WDQGDUG

HUURU

NJG

6WDQGDUG

HUURURI

SUHGLFWLRQ

NJG

:DWHU\HDU :DWHU\HDU

October 10.9 1.97 2.20 October 10.4 1.24 1.56

November 12.3 1.95 2.28 November 13.0 1.83 2.27

December 14.9 2.45 2.89 December 11.5 1.39 1.74

January 28.1 11.6 11.9 January 17.0 3.26 3.73

February 20.3 3.46 4.06 February 19.9 4.67 5.17

March 21.0 3.85 4.41 March 15.9 1.91 2.45

April 22.5 4.14 4.75 April 11.8 1.51 1.86

May 32.5 9.89 10.4 May 11.2 1.59 1.92

June 19.1 2.99 3.40 June 12.6 1.61 2.03

July 18.9 3.10 3.60 July 10.2 1.39 1.68

August 14.0 1.99 2.36 August 9.34 1.26 1.52

September 11.8 1.50 1.85 September 9.19 1.21 1.51

:DWHU\HDU :DWHU\HDU

October 8.09 1.01 1.32 October 8.90 1.44 1.73

November 13.9 2.55 2.93 November 8.58 1.23 1.46

December 13.1 2.36 2.74 December 8.93 1.29 1.53

January 13.9 2.70 3.02 January 11.1 1.79 2.14

February 13.6 1.92 2.32 February 8.92 1.26 1.51

March 18.2 3.69 4.17 March 10.9 1.42 1.76

April 14.6 1.95 2.38 April 10.6 1.40 1.74

May 16.1 3.30 3.69 May 8.93 1.38 1.61

June 13.9 2.05 2.44 June 10.7 2.11 2.46

July 12.8 1.95 2.28 July 14.6 3.05 3.45

August 10.9 1.64 1.92 August 8.79 1.24 1.48

September 10.7 1.72 1.99 September 7.27 1.13 1.31

:DWHU\HDU :DWHU\HDU

October 8.16 1.19 1.42 October 11.9 3.01 3.31

November 7.31 1.14 1.33 November 11.2 2.13 2.45

December 8.79 1.48 1.76 December 11.5 3.07 3.30

January 10.9 1.87 2.20 January 13.7 2.74 3.10

February 9.57 1.34 1.63 February 13.7 2.34 2.74

March 12.5 1.98 2.38 March 14.8 2.76 3.17

April 13.6 2.29 2.72 April 16.8 3.04 3.50

May 15.3 5.16 5.46 May 11.1 1.46 1.77

June 11.9 1.64 2.04 June 10.7 1.42 1.74

July 10.4 1.45 1.74 July 12.1 1.66 2.02

August 13.2 3.00 3.33 August 12.7 1.95 2.31

September 8.58 1.20 1.43 September 9.96 1.39 1.68

:DWHU\HDU :DWHU\HDU

October 8.54 1.19 1.42 October 12.5 2.61 2.92

November 8.14 1.20 1.41 November 15.8 5.22 5.52

December 10.9 1.88 2.20 December 13.9 2.91 3.22

January 12.6 2.20 2.55 January 25.2 10.9 11.2

February 14.2 2.37 2.80 February 18.2 4.03 4.43

March 13.4 2.42 2.81 March 19.0 5.78 6.07

April 12.0 1.87 2.23 April 16.8 3.50 3.87

May 14.2 4.17 4.49 May 13.5 2.88 3.16

June 20.3 6.36 6.75 June 11.8 2.69 2.92

July 27.4 12.1 12.3 July 16.6 4.13 4.47

August 16.2 2.93 3.30 August 12.6 2.83 3.08

September September 17.5 6.94 7.19
 $VVHVVPHQWRI:DWHU4XDOLW\&RQGLWLRQVLQWKH-%&RQYHUVH/DNH:DWHUVKHG0RELOH&RXQW\$ODEDPD¥

Appendix 2. Monthly mean load tables for selected surface-water sites in the J.B. Converse Lake watershed, 

Mobile County, Alabama, 1990–98—Continued

[kg/d, kilograms per day]

Crooked Creek near Fairview, 02479980 (site CRO)

Total phosphorus

0RQWK

'DLO\PHDQ

FRQVWLWXHQW

GLVFKDUJH

NJG

6WDQGDUG

HUURU

NJG

6WDQGDUG

HUURURI

SUHGLFWLRQ

NJG

0RQWK

'DLO\PHDQ

FRQVWLWXHQW

GLVFKDUJH

NJG

6WDQGDUG

HUURU

NJG

6WDQGDUG

HUURURI

SUHGLFWLRQ

NJG

:DWHU\HDU :DWHU\HDU

October 0.323 0.078 0.092 October .407 .088 .106

November .585 .148 .212 November 1.17 .410 .563

December 1.26 .426 .565 December .656 .132 .167

January 10.6 7.22 8.01 January 3.20 1.52 1.94

February 2.74 .974 1.29 February 5.04 2.56 3.16

March 3.29 1.30 1.69 March 1.88 .485 .717

April 3.32 1.16 1.43 April .677 .144 .177

May 8.42 4.36 4.95 May .702 .144 .236

June 4.68 .454 .558 June .915 .201 .294

July 1.84 .595 .731 July .462 .101 .129

August .769 .183 .223 August .380 .081 .106

September .544 .123 .157 September .479 .110 .177

:DWHU\HDU :DWHU\HDU

October 0.284 0.061 0.075 October .839 .329 .534

November 1.81 .710 .880 November .471 .093 .123

December 2.27 1.13 1.56 December .569 .110 .146

January 6.40 4.95 6.45 January 1.76 .710 1.10

February 1.41 .275 .377 February .553 .111 .141

March 4.37 1.83 2.28 March 1.07 .119 .317

April 1.58 .304 .418 April .934 .169 .273

May 5.75 3.66 4.90 May .511 .109 .143

June 1.34 .296 .400 June 1.74 .779 1.22

July 1.06 .229 .299 July 2.77 1.22 1.54

August .707 .143 .186 August .478 .094 .134

September .738 .159 .208 September .275 .062 .074

:DWHU\HDU :DWHU\HDU

October 0.481 0.102 0.157 October 2.72 1.65 2.06

November .388 .080 .127 November 1.73 .797 1.08

December 1.01 .385 .615 December 11.0 10.5 12.7

January 1.72 .620 .877 January 2.83 1.23 1.54

February .801 .155 .230 February 2.77 1.13 1.56

March 2.30 .811 1.20 March 3.63 1.56 2.12

April 2.68 .964 1.37 April 4.11 1.71 2.31

May 14.2 11.6 14.1 May .869 .187 .231

June 1.40 .378 .606 June .814 .174 .232

July .739 .149 .198 July 1.16 .288 .370

August 3.55 2.22 2.91 August 1.39 .423 .548

September .454 .096 .121 September .693 .172 .228

:DWHU\HDU :DWHU\HDU

October 0.444 0.108 0.127 October 1.77 .870 1.14

November .414 .105 .123 November 4.39 2.80 3.25

December 1.43 .559 .751 December 2.05 .888 1.13

January 2.01 .787 1.02 January 13.1 9.19 10.2

February 2.31 .772 .989 February 3.25 1.24 1.47

March 2.37 .875 1.18 March 9.51 6.64 8.13

April 1.41 .381 .568 April 2.35 .733 .909

May 3.93 2.07 2.69 May 1.26 .346 .454

June 5.80 3.00 3.47 June .838 .226 .302

July 14.2 10.1 11.1 July 2.23 .884 1.07

August 1.86 .586 .672 August .948 .292 .369

September .758 .201 .233 September 20.6 22.0 24.8
$SSHQGL[HV 

Appendix 2. Monthly mean load tables for selected surface-water sites in the J.B. Converse Lake watershed, 

Mobile County, Alabama, 1990–98—Continued

[kg/d, kilograms per day]

Hamilton Creek at Snow Road near Semmes, 02480002 (site HAM)

Total nitrogen

0RQWK

'DLO\PHDQ

FRQVWLWXHQW

GLVFKDUJH

NJG

6WDQGDUG

HUURU

NJG

6WDQGDUG

HUURURI

SUHGLFWLRQ

NJG

0RQWK

'DLO\PHDQ

FRQVWLWXHQW

GLVFKDUJH

NJG

6WDQGDUG

HUURU

NJG

6WDQGDUG

HUURURI

SUHGLFWLRQ

NJG

:DWHU\HDU :DWHU\HDU

October 31.5 2.01 2.12 October 33.3 1.33 1.52

November 31.0 1.91 2.04 November 36.4 1.44 1.69

December 35.8 1.83 2.02 December 36.5 1.66 1.85

January 81.5 6.57 7.13 January 51.9 2.79 3.07

February 45.5 2.20 2.48 February 58.3 2.92 3.37

March 46.6 2.09 2.37 March 42.5 1.70 1.97

April 53.4 2.33 2.72 April 34.5 1.17 1.40

May 74.6 5.53 6.02 May 32.5 1.30 1.49

June 44.3 1.85 2.11 June 40.8 1.50 1.78

July 46.2 1.99 2.26 July 35.4 1.35 1.56

August 41.1 1.70 1.92 August 31.4 1.41 1.58

September 39.2 1.59 1.81 September 32.2 1.41 1.61

:DWHU\HDU :DWHU\HDU

October 27.7 1.46 1.58 October 31.0 1.64 1.82

November 41.8 2.18 2.44 November 32.8 1.82 1.96

December 39.3 1.99 2.25 December 31.2 1.74 1.87

January 65.0 11.5 12.0 January 34.1 1.92 2.08

February 39.5 2.10 2.30 February 27.8 1.52 1.65

March 58.5 4.09 4.53 March 36.3 1.84 2.02

April 42.7 1.94 2.18 April 35.0 1.57 1.77

May 47.6 2.47 2.80 May 28.7 1.47 1.60

June 36.3 1.48 1.70 June 48.3 4.59 4.93

July 38.6 1.77 1.97 July 38.6 1.96 2.16

August 33.0 1.51 1.67 August 28.7 1.52 1.65

September 31.0 1.49 1.65 September 26.8 1.57 1.68

:DWHU\HDU :DWHU\HDU

October 30.5 1.67 1.83 October 48.5 4.75 5.10

November 29.5 1.72 1.89 November 39.1 2.38 2.58

December 31.5 1.83 1.98 December 82.3 27.5 28.1

January 37.9 2.31 2.51 January 40.5 2.52 2.72

February 30.6 1.68 1.83 February 42.9 2.65 2.98

March 39.4 2.14 2.35 March 47.5 3.40 3.74

April 48.1 3.00 3.31 April 57.9 4.34 4.70

May 82.2 20.6 21.0 May 32.3 1.37 1.55

June 36.6 1.67 1.89 June 38.9 1.82 2.08

July 35.1 1.59 1.77 July 35.6 1.53 1.73

August 43.4 3.07 3.37 August 39.0 1.81 2.02

September 25.1 1.60 1.70 September 32.1 1.49 1.65

:DWHU\HDU :DWHU\HDU

October 28.8 1.48 1.61 October 38.4 2.23 2.45

November 27.8 1.57 1.69 November 52.9 3.83 4.14

December 33.2 1.89 2.07 December 41.0 2.88 3.02

January 31.0 1.84 1.97 January 92.4 20.0 20.4

February 34.6 1.97 2.15 February 40.6 2.91 3.08

March 34.8 1.98 2.18 March 74.8 18.8 19.2

April 31.5 1.79 1.95 April 36.5 2.66 2.80

May 41.7 3.00 3.24 May 33.3 2.53 2.63

June 52.7 3.86 4.17 June 28.9 2.59 2.68

July 94.0 19.2 19.7 July 35.9 2.76 2.88

August 37.1 1.87 2.04 August 28.3 2.52 2.60

September 35.1 1.88 2.03 September 165 99.8 100
 $VVHVVPHQWRI:DWHU4XDOLW\&RQGLWLRQVLQWKH-%&RQYHUVH/DNH:DWHUVKHG0RELOH&RXQW\$ODEDPD¥

Appendix 2. Monthly mean load tables for selected surface-water sites in the J.B. Converse Lake watershed, 

Mobile County, Alabama, 1990–98—Continued

[kg/d, kilograms per day]

Hamilton Creek at Snow Road near Semmes, 02480002 (site HAM)

Total Kjeldahl nitrogen

0RQWK

'DLO\PHDQ

FRQVWLWXHQW

GLVFKDUJH

NJG

6WDQGDUG

HUURU

NJG

6WDQGDUG

HUURURI

SUHGLFWLRQ

NJG

0RQWK

'DLO\PHDQ

FRQVWLWXHQW

GLVFKDUJH

NJG

6WDQGDUG

HUURU

NJG

6WDQGDUG

HUURURI

SUHGLFWLRQ

NJG

:DWHU\HDU :DWHU\HDU

October 8.44 1.17 1.29 October 9.51 .940 1.12

November 7.83 .994 1.19 November 11.8 1.25 1.72

December 11.1 1.28 1.74 December 10.3 1.07 1.29

January 53.9 18.4 19.8 January 22.6 3.05 3.75

February 18.0 2.11 2.80 February 30.2 5.49 6.66

March 20.1 2.38 2.98 March 16.2 1.63 2.14

April 30.6 4.53 5.61 April 10.9 .998 1.23

May 58.3 17.2 18.9 May 10.7 1.05 1.33

June 22.4 2.67 3.15 June 18.7 2.02 2.53

July 24.9 3.14 3.73 July 13.5 1.33 1.63

August 17.8 2.03 2.34 August 10.1 1.03 1.27

September 15.1 1.68 1.97 September 10.5 1.13 1.50

:DWHU\HDU :DWHU\HDU

October 6.08 0.753 0.849 October 9.07 1.25 1.70

November 16.4 2.49 3.09 November 8.35 1.06 1.20

December 13.7 1.99 2.68 December 7.01 .870 .992

January 28.5 19.3 20.3 January 9.23 1.18 1.49

February 12.5 1.45 1.76 February 5.47 .720 .810

March 32.8 9.94 11.1 March 11.1 1.30 1.59

April 17.6 2.05 2.53 April 11.3 1.24 1.50

May 26.3 5.08 6.14 May 7.77 .945 1.10

June 14.1 1.50 1.81 June 30.7 11.4 12.6

July 16.2 1.94 2.25 July 17.1 2.37 2.82

August 11.0 1.22 1.44 August 7.75 .961 1.08

September 6.80 1.01 1.18 September 6.09 .836 .926

:DWHU\HDU :DWHU\HDU

October 8.65 1.20 1.58 October 26.0 10.4 11.4

November 7.50 1.12 1.54 November 13.1 2.04 2.45

December 8.04 1.13 1.47 December 23.8 19.9 20.4

January 12.1 1.89 2.34 January 12.9 1.97 2.40

February 6.83 .837 .963 February 15.5 3.62 4.38

March 13.9 1.91 2.33 March 21.2 6.32 7.14

April 24.3 5.34 6.16 April 31.6 9.13 10.0

May 47.1 36.8 37.7 May 9.69 1.03 1.21

June 14.5 1.76 2.21 June 16.9 2.38 2.99

July 12.7 1.41 1.65 July 13.2 1.47 1.78

August 23.0 6.35 7.39 August 15.5 1.93 2.27

September 5.23 .760 .838 September 9.17 1.07 1.24

:DWHU\HDU :DWHU\HDU

October 6.51 0.819 0.922 October 13.1 2.28 2.79

November 5.51 .747 .831 November 22.0 5.57 6.20

December 8.75 1.25 1.58 December 11.6 1.98 2.15

January 6.88 .935 1.07 January 34.9 18.3 18.8

February 9.32 1.25 1.51 February 12.0 2.09 2.31

March 10.9 1.74 2.18 March 24.9 16.1 16.6

April 9.40 1.27 1.58 April 11.6 2.07 2.29

May 20.4 4.84 5.54 May 10.0 1.83 1.95

June 29.7 7.64 8.47 June 8.75 1.70 1.91

July 55.9 29.8 30.6 July 12.9 2.39 2.58

August 13.2 1.75 1.97 August 7.75 1.52 1.63

September 10.8 1.51 1.68 September 38.6 30.7 31.3
$SSHQGL[HV 

Appendix 2. Monthly mean load tables for selected surface-water sites in the J.B. Converse Lake watershed, 

Mobile County, Alabama, 1990–98—Continued

[kg/d, kilograms per day]

Hamilton Creek at Snow Road near Semmes, 02480002 (site HAM)

Total inorganic nitrogen

0RQWK

'DLO\PHDQ

FRQVWLWXHQW

GLVFKDUJH

NJG

6WDQGDUG

HUURU

NJG

6WDQGDUG

HUURURI

SUHGLFWLRQ

NJG

0RQWK

'DLO\PHDQ

FRQVWLWXHQW

GLVFKDUJH

NJG

6WDQGDUG

HUURU

NJG

6WDQGDUG

HUURURI

SUHGLFWLRQ

NJG

:DWHU\HDU :DWHU\HDU

October 19.6 0.734 0.815 October 20.8 .544 .660

November 20.0 .744 .830 November 21.9 .549 .682

December 22.4 .737 .843 December 24.5 .659 .793

January 27.8 .899 1.03 January 28.0 .843 .983

February 27.2 .854 .998 February 27.7 .781 .937

March 26.3 .792 .924 March 25.6 .645 .794

April 25.3 .766 .896 April 22.2 .563 .694

May 25.6 .873 .988 May 19.4 .572 .672

June 22.7 .690 .806 June 21.5 .579 .701

July 22.4 .697 .806 July 19.7 .523 .632

August 22.0 .675 .782 August 17.8 .501 .596

September 22.0 .650 .765 September 18.1 .501 .604

:DWHU\HDU :DWHU\HDU

October 17.7 0.547 0.633 October 18.3 .580 .670

November 22.7 .655 .779 November 22.2 .698 .808

December 23.4 .637 .765 December 22.4 .676 .787

January 24.3 .655 .790 January 23.3 .689 .809

February 25.9 .732 .883 February 20.9 .684 .790

March 25.5 .731 .864 March 24.0 .683 .809

April 24.5 .690 .824 April 22.5 .639 .761

May 22.6 .656 .772 May 18.4 .640 .722

June 20.6 .585 .697 June 18.8 .661 .748

July 20.9 .641 .744 July 20.0 .635 .732

August 19.1 .559 .656 August 17.6 .565 .648

September 18.8 .557 .656 September 17.2 .587 .665

:DWHU\HDU :DWHU\HDU

October 19.0 0.609 0.700 October 20.1 .652 .747

November 19.2 .651 .741 November 24.1 .803 .917

December 21.6 .682 .786 December 23.3 .718 .835

January 23.9 .739 .858 January 26.4 .827 .954

February 23.3 .695 .824 February 25.8 .755 .896

March 24.2 .712 .837 March 24.6 .716 .843

April 23.1 .723 .839 April 25.3 .789 .916

May 20.7 .686 .783 May 21.9 .606 .723

June 21.0 .617 .727 June 21.5 .616 .732

July 20.9 .623 .728 July 21.1 .597 .709

August 19.7 .623 .719 August 22.3 .683 .793

September 16.7 .612 .684 September 21.4 .622 .735

:DWHU\HDU :DWHU\HDU

October 21.1 0.629 0.735 October 24.2 .850 .956

November 21.8 .681 .789 November 26.4 .993 1.10

December 23.8 .737 .854 December 29.3 1.17 1.28

January 24.7 .771 .892 January 28.7 1.20 1.31

February 25.3 .780 .918 February 29.0 1.16 1.28

March 23.5 .786 .895 March 27.3 1.13 1.23

April 21.7 .787 .884 April 25.7 1.10 1.20

May 20.6 .818 .900 May 24.0 1.06 1.15

June 23.1 .788 .895 June 19.9 1.04 1.10

July 23.9 .967 1.06 July 22.8 1.04 1.12

August 23.2 .765 .872 August 20.0 1.01 1.07

September 23.6 .809 .917 September 19.3 1.08 1.14
 $VVHVVPHQWRI:DWHU4XDOLW\&RQGLWLRQVLQWKH-%&RQYHUVH/DNH:DWHUVKHG0RELOH&RXQW\$ODEDPD¥

Appendix 2. Monthly mean load tables for selected surface-water sites in the J.B. Converse Lake watershed, 

Mobile County, Alabama, 1990–98—Continued

[kg/d, kilograms per day]

Hamilton Creek at Snow Road near Semmes, 02480002 (site HAM)

Total phosphorus

0RQWK

'DLO\PHDQ

FRQVWLWXHQW

GLVFKDUJH

NJG

6WDQGDUG

HUURU

NJG

6WDQGDUG

HUURURI

SUHGLFWLRQ

NJG

0RQWK

'DLO\PHDQ

FRQVWLWXHQW

GLVFKDUJH

NJG

6WDQGDUG

HUURU

NJG

6WDQGDUG

HUURURI

SUHGLFWLRQ

NJG

:DWHU\HDU :DWHU\HDU

October 0.637 0.176 0.206 October .744 .184 .221

November .595 .154 .207 November .972 .242 .364

December .902 .232 .352 December .823 .184 .237

January 5.766 3.41 4.08 January 2.04 .618 .822

February 1.56 .418 .611 February 2.97 1.18 1.59

March 1.78 .485 .647 March 1.45 .334 .478

April 2.91 1.05 1.36 April .931 .204 .258

May 6.56 3.66 4.59 May .941 .210 .283

June 1.99 .551 .677 June 1.72 .426 .567

July 2.23 .663 .821 July 1.18 .271 .347

August 1.51 .386 .464 August .853 .196 .258

September 1.25 .313 .384 September .899 .209 .311

:DWHU\HDU :DWHU\HDU

October 0.479 0.123 0.147 October .821 .200 .363

November 1.49 .446 .642 November .713 .160 .205

December 1.25 .368 .598 December .596 .136 .172

January 5.19 4.14 5.66 January .846 .186 .301

February 1.12 .231 .333 February .470 .117 .142

March 3.83 1.92 2.61 March 1.06 .221 .325

April 1.68 .390 .551 April 1.09 .224 .314

May 2.79 1.04 1.49 May .732 .158 .210

June 1.31 .281 .376 June 3.98 2.23 3.10

July 1.53 .342 .444 July 1.75 .447 .612

August .984 .212 .276 August .710 .161 .200

September .763 .170 .218 September .540 .134 .161

:DWHU\HDU :DWHU\HDU

October 0.821 0.199 0.345 October 3.43 2.08 2.73

November .716 .184 .348 November 1.37 .416 .575

December .765 .190 .319 December 8.92 8.77 11.1

January 1.24 .359 .537 January 1.40 .435 .604

February .638 .152 .191 February 1.89 .778 1.19

March 1.47 .389 .551 March 2.87 1.40 1.97

April 2.89 1.16 1.54 April 4.20 2.11 2.66

May 11.1 9.47 11.5 May 1.05 .252 .307

June 1.56 .377 .549 June 2.02 .623 .866

July 1.31 .290 .371 July 1.50 .378 .483

August 2.86 1.35 1.95 August 1.75 .483 .606

September .490 .130 .155 September .970 .252 .305

:DWHU\HDU :DWHU\HDU

October 0.661 0.184 0.215 October 1.63 .627 .858

November .550 .163 .188 November 3.00 1.52 1.85

December .967 .306 .431 December 1.38 .472 .539

January .734 .214 .260 January 8.67 7.02 8.46

February 1.06 .316 .410 February 1.51 .526 .624

March 1.34 .450 .644 March 7.95 6.80 8.58

April 1.14 .330 .453 April 1.54 .504 .612

May 2.84 1.28 1.65 May 1.32 .403 .463

June 4.28 2.06 2.58 June 1.18 .371 .493

July 13.0 10.3 12.2 July 1.75 .568 .664

August 1.59 .458 .537 August 1.00 .314 .374

September 1.26 .370 .430 September 33.3 39.4 44.2
Appendixes 129

Appendix 3. Methods and results for Giardia and Cryptosporidium analyses for October 1996 to May 1998[na, not applicable; —, no results for this assay; gal/min, gallons per minute; >, greater than; ICR, Information Collection Rule]

Sample 

date Sample location

Treatment 

characteristics of sample Gallons sampled Liters sampled Other conditions Volume assayed (gallons) Volume assayed (liters) Giardia lamblia cysts Giardia sp. cysts Cryp

spo

idiu

oocy

06/02/93 Pumping station Raw 250 na SC=25 125.00 473.13 0 — 0 06/02/93 U.S. Highway 98 bridge Raw 200 na na 100.00 378.50 0 — 0 06/03/93 H.E. Myers Filtration Plant Raw 210 na na 105.00 397.43 0 — 0 06/03/93 Outside spigot at Howard Johnson Hotel Filtered and 

disinfected

300 na na 150.00 567.75 0 — 0 

08/03/93 Pumping station Raw 247 na na 123.50 467.45 0 1 0 08/04/93 Outside spigot at Howard Johnson Hotel Filtered and 

disinfected

406.3 na na 203.00 768.36 0 — 0 

08/04/93 Mouth of Crooked Creek Raw 195.5 na Clogged filter 97.50 369.04 0 — 0 08/04/93 H.E. Myers Filtration Plant Raw 126 na Clogged filter 63.00 238.46 0 — 0 11/03/93 U.S. Highway 98 bridge Raw 212 na na 106.00 401.21 0 — 0 11/03/93 H.E. Myers Filtration Plant Raw 220 na na 110.00 416.35 0 — 0 11/04/93 Outside spigot at Howard Johnson Hotel Filtered and 

disinfected

225 na na 112.50 425.81 0 — 0 

11/04/93 Pumping station Raw 200 na na 100.00 378.50 0 — 0 02/02/94 Pumping station Raw 200 na na 100.00 378.50 0 — 0 02/02/94 Boat Landing—Mouth of Crooked 

Creek

Raw 210 na na 105.00 397.43 0 — 0 

02/03/94 Outside spigot at Howard Johnson Hotel Filtered and 

disinfected

260 na na 130.00 492.05 0 — 0 

02/03/94 Myers Filtration Plant Holding 

Reservoir

Raw 241 na na 120.50 456.09 0 — 0 

05/23/94 Outside spigot at Howard Johnson Hotel Filtered and 

disinfected

310 na na 154.95 586.5 0 — 0 

05/23/94 U.S. Highway 98 bridge Raw 203 na na 101.45 384 0 — 0 05/24/94 Pumping station Raw 265 na na 132.50 501.5 0 — 0 05/24/94 H.E. Myers Filtration Plant Raw 160 na Filter was 

clogging. Filter

rate = 0.75gal/

min at end.

80.05 303 0 — 0 

08/11/94 H.E. Myers Filtration Plant Raw 250 na na 124.97 473 0 — 0 08/11/94 Mouth of Crooked Creek Raw 210 na na 105.15 398 0 — 0 08/03/94 Outside spigot at Howard Johnson Hotel Filtered and 

disinfected

343 na na 171.47 649 0 — 0 

08/02/94 Pumping station Raw 201 na na 100.66 381 0 — 0 11/01/94 U.S. Highway 98 bridge Raw 160.6 na na 80.32 304 0 — 0 11/02/94 H.E. Myers Filtration Plant Raw 250.3 na na 125.23 474 0 — 0 11/02/94 Pumping station Raw 240 na na 119.95 454 0 — 0 11/03/94 Outside spigot at Howard Johnson Hotel Filtered and 

disinfected

210.3 na na 105.15 398 0 — 0 

02/27/95 H.E. Myers Filtration Plant Raw 205 na na 49.93 189 0 — 0 02/28/95 Pumping station Raw 244 na na 61.03 231 0 — 0 
130 Assessment of Water-Quality Conditions in the J.B. Converse Lake Watershed, Mobile County, Alabama, 1990–98 02/28/95 Outside spigot at Howard Johnson Hotel Filtered and disinfected 209 na na 49.93 189 0 — 0 

03/01/95 Mouth of Crooked Creek Raw 200 na na 49.93 189 0 — 0 05/22/95 H.E. Myers Filtration Plant Raw 146 na na 36.72 139 0 — 0 05/22/95 Outside spigot at Howard Johnson Hotel Filtered and disinfected 263 na na 118.36 448 0 — 0 

05/23/95 U.S. Highway 98 bridge Raw 147 na na 36.72 139 0 — 0 05/23/95 Pumping station Raw 169 na na 42.27 160 0 — 0 09/12/95 Pumping station Raw 300 na na na na — 0 0 09/13/95 U.S. Highway 98 bridge Raw >113 na Dial malfunc- tioned/could not reengage by backflushing na na — 0 0 

09/13/95 Outside spigot at Howard Johnson Hotel Filtered and disinfected ? na na na na — 0 0 09/14/95 H.E. Myers Filtration Plant Raw 146 na Filter clogged na na — 0 0 01/25/96 Outside spigot at Howard Johnson Hotel Filtered and disinfected 580 na na 115.98 439 0 — 0 

01/24/96 Pumping station Raw 371 na na 11.10 42 0 — 0 01/24/96 U.S. Highway 98 bridge Raw 288 na na 11.62 44 0 — 0 01/25/96 H.E. Myers Filtration Plant Raw 278 na na 27.74 105 0 — 1 03/14/96 Outside spigot at Howard Johnson Hotel Filtered and disinfected 231 na na 115.46 437 0 — 0 

03/13/96 Pumping station Raw 455 na na 13.74 52 0 — 0 03/13/96 H.E. Myers Filtration Plant Raw 232 na na 9.25 35 0 — 0 03/14/96 Mouth of Crooked Creek Raw 222 na na 8.98 34 0 — 0 06/06/96 Pumping station Raw 321 na na 16.12 61 6 — 0 06/06/96 U.S. Highway 98 bridge Raw 150 na na 7.40 28 6 — 1 06/07/96 Outside spigot at Howard Johnson Hotel Filtered and disinfected 200 na na 80.05 303 0 — 0 

06/07/96 H.E. Myers Filtration Plant Raw 150 na na 6.08 23 0 — 0 08/05/96 Outside spigot at Howard Johnson Hotel Filtered and disinfected 221 na na 176.75 669 0 — 0 

08/06/96 Mouth of Crooked Creek Raw 200 na na 3.96 15 0 — 0 08/06/96 Pumping station Raw 829 na na 8.19 31 0 — 0 08/07/96 Myers Filtration Plant Holding Reservoir Raw 97 na na 1.85 7 0 — 0 

10/29/96 Outside spigot at Howard Johnson Hotel Filtered and disinfected 200 na Dechlorination 16.12 61 0 — 0 

10/29/96 Myers Filtration Plant Holding 

Reservoir

Raw 140 na na 2.91 11 0 — 0 

10/31/96 Pumping station Raw 279 na na 5.55 21 0 — 0 10/30/96 U.S. Highway 98 bridge Raw 214 na na 4.23 16 0 — 0 

Appendix 3. Methods and results for Giardia and Cryptosporidium analyses for October 1996 to May 1998—Continued[na, not applicable; —, no results for this assay; gal/min, gallons per minute; >, greater than; ICR, Information Collection Rule]

Sample 

date Sample location

Treatment 

characteristics of sample Gallons sampled Liters sampled Other conditions Volume assayed (gallons) Volume assayed (liters) Giardia lamblia cysts Giardia sp. cysts Cryp

spo

idiu

oocy
Appendixes 131

01/07/97 Pumping station Raw 282 na na 14.00 53 0 — 0 01/08/97 Mouth of Crooked Creek Raw 232 na na 6.87 26 0 — 0 01/06/97 Outside spigot at Howard Johnson Hotel Filtered and 

disinfected

190 na Dechlorination 151.92 575 0 — 0 

01/07/97 Myers Filtration Plant Holding 

Reservoir

Raw 238 na na 7.13 27 0 — 0 

04/16/97 U.S. Highway 98 bridge Raw 540 Meter inoperable 4.23 16 0 — 0 04/14/97 Outside spigot at Howard Johnson Hotel Filtered and 

disinfected

202 763 Dechlorination 80.58 305 0 — 0 

04/15/97 Myers Filtration Plant Holding 

Reservoir

Raw 136 515 na 2.64 10 0 — 0 

04/15/97 Pumping station Raw 403 1523 na 7.93 30 0 — 0 07/22/97 Myers Filtration Plant Holding 

Reservoir

Raw 181 na na 3.70 14 0 — 0 

07/22/97 Outside spigot at Howard Johnson Hotel Filtered and 

disinfected

279 na Dechlorination 111.49 422 0 — 0 

07/24/97 Mouth of Crooked Creek Raw 200.2 na na 3.96 15 0 — 0 07/21/97 Pumping station Raw 306.9 na na 6.08 23 0 — 0 10/16/97 Myers Filtration Plant Holding 

Reservoir

Raw 200 757 na 11.89 45 0 — 0 

10/16/97 Outside spigot at Howard Johnson Hotel Treated 235.1 890 Dechlorination 28.27 107 0 — 0 

10/15/97 U.S. Highway 98 bridge Raw 229.1 867 na 16.12 61 0 — 0 

10/15/97 Pumping station Raw 201 761 na 12.15 46 0 — 0 

01/15/98 H.E. Myers Filtration Plant Raw 93.5 354 na 9.35 35.4 0 — 0 01/16/98 Outside spigot at Howard Johnson Hotel Treated 225 852 No dechlorination 117.04 443 0 — 0 01/16/98 Mouth of Crooked Creek Raw 200 757 na 8.01 30.3 0 — 0 01/15/98 Pumping station Raw 281 1064 na 14.06 53.2 0 — 0 05/19/98 U.S. Highway 98 bridge Raw 56 212 na na na — 0 0 05/20/98 Pumping station Raw 75.4 285 na na na — 0 0 05/20/98 Myers Filtration Plant Holding 

Reservoir

Raw 91.3 346 na na na — 0 0 

05/21/98 Myers Filtration Plant Sink Treated 392.3 1485 No dechlorination na na — 0 0 

Appendix 3. Methods and results for Giardia and Cryptosporidium analyses for October 1996 to May 1998—Continued[na, not applicable; —, no results for this assay; gal/min, gallons per minute; >, greater than; ICR, Information Collection Rule]

Sample 

date Sample location

Treatment 

characteristics of sample Gallons sampled Liters sampled Other conditions Volume assayed (gallons) Volume assayed (liters) Giardia lamblia cysts Giardia sp. cysts Cryp

spo

idiu

oocy