- -. 

EVE 

215 

198 

Report SFRC-83/06 

Mowry Canal (C-103): 

Water Quality and 

Discharge into Biscayne 

Bay, Florida, 1975- 1981 

Everglades National Park, South Florida Research Center, PO. Box 279, Homestead, Florida 33030 

-. 
Mowr y Canal (C- 103): Water Quality and Discharge 

into Biscayne Bay, Florida, 1975-1981 

Report SFRC-83/06 

Daniel J. Scheidt and Mark D. Flora 

National Park Service 

South Florida Research Center 

Everglades National Park 

Homestead, Florida 33030 

October 1983 
Scheidt, Daniel J., and Mark D. Flora. 1983. Mowry Canal (C-103): Water Quality 

and Discharge into Biscayne Bay, Florida, 1975-1 98 1. South Florida Research 

Center Report SFRC-83/06. 41 p. 
TABLE OF CONTENTS 

LIST OF TABLES .................. ii 

LIST OF FIGURES .................. iii 

INTRODUCTION ................... 1 

BasinDescription .... Rainfall . Discharge Analysis 

METHODS AND ANALYSIS . . 

Water Quality Evaluation . Physical Parameters ... Nutrients ...... Nitrogen ..... Phosphorus .... Bacteria ...... Heavy Metals and Pesticides . 

SUMMARY AND CONCLUSIONS . 

ACKNOWLEDGEMENTS ... 

LITERATURE CITED .... 
LIST OF TABLES 

Table 

1. 

2. 

Page 

Land use in the Mowry Canal (C-103) Basin . 6 

Mean, standard deviation and range of selected physical 

parameters in the Mowry Canal during period of study .. 14 

Mean, standard deviation and range of nutrients in the 

Mowry Canal during period of study ......... 23 

Bacteriological counts and Fc/Fs ratio for DERM stations 

exceeding total coliform standard of 1000 MPNI100 ml 

or fecal coliform standard of 200 MPN/100 ml . 33 

Heavy metal concentrations (water column) in Mowr y 

Canal at S-20F (USGS 02290725) .......... 35 

Total heavy metal concentrations in bottom material in 

Mowry Canal at S-20F (USGS 02290725) ........ 36 

Pesticides in bottom material at USGf station 02290725. All 

concentrations are reported as ug kg- . 37 

Common agricultural pesticides utilized in Dade County, 

Florida (1980-198 1) .............. 38 
LIST OF FIGURES 

Figure 

1. 

Page 

Major canals and canal basin delineations for southeastern 

Dade County, Florida ............ 

Annual discharge from Mowry Canal, Snapper Creek Canal, 

and Black Creek Canal fgr water-years 1975-1980. .... 

The Mowry Canal (C- 103) Basin ......... 

Monthly discharge from the Mowry Canal and monthly rainfall 

within the Mowry Canal Basin .......... 

Mean monthly rainfall at Homestead Experimental Station for 

water-years 1975-198 1 ............ 

Mean monthly discharge at Mowry Canal (USGS 02290725) for 

water-years 1975-1981 ............ 

Annual rainfall at Homestead Experimental Station and annual 

discharge (USGS 02290725) from Mowry Canal (water-years 

1975-1981) ............... 

Relationship between mean monthly rainfall at Homestead 

Experimental Station and mean monthly discharge from Mowry 

Canal (USGS 02290725) ............ 

Relationship between mean monthly rainfall at Homestead 

Experimental Station and mean monthly discharge from Mowry 

Canal (USGS 02290725) one month later ....... 

Water tempeature at DERM Mowry can& stations 38-41 

(1980-1981) ............... 

Dissolved oxygen concentration at DERM Mowry Canal 

sampling stations 38-41 (1980-1981) ........ 

Specific conductance at DERM Mowry Canal 

sampling stations 38-41 (1980-1981) ........ 

Specific conductance at DERM Mowry Canal 

sampling stations 38 and 39 (1980-1981) ....... 

Concentrations of alkalinity at USGS Mowry Canal 

station 02290725 (1 975-1 980) .......... 

pH value at USGS Mowry Canal station 02290725 (1975-1980) . 
Secchi disc transparency at DERM Mowry Canal sampling 

stations 38-41 (1980-1981) . . . . . . . . . . . . . 21 

Nitrite + nitrate nitrogen at DERM Mowry Canal sampling 

stations 38-41 (1 980-1 98 1) . . . . . . . . . . . . . 24 

Nitrate nitrogen at selected Dade County DERM Canal Monitoring 

Program stations (1 980- 198 1) . . . . . . . . . . . . 25 

Ammonia nitrogen at USCS Mowry Canal station 02290725 

(1 975- 1980) . . . . . . . . . . . . . . . . . 27 

Nitrite + nitrate nitrogen at USCS Mowry Canal station 02290725 

(1 975- 1980) . . . . . . . . . . . . . . . . . 27 

Organic nitrogen at USCS Mowry Canal station 0229072'5 

(1975-1980) . . . . . . . . . . . . . . . . . 28 

Total nitrogen at USCS Mowry Canal station 02290725 

(1975-1980) . . . . . . . . . . . . . . . . . 28 

Total phosphorus at USCS Mowry Canal station 02290725 

(1975-1980) . . . . . . . . . . . . . . . . . 30 

Total coli form bacteria at DERM Mowr y Canal sampling 

stations 38-41(1980-1981) . . . . . . . . . . . . . 31 

Fecal coliform bacteria at DERM Mowr y Canal sampling 

stations 38-41 (1980-1981) . . . . . . . . . . . . . 32 
INTRODUCTION 

The Mowry Canal (C-103) is located on the lower east coast of Florida approximately 25 miles south of Miami. Because of its location, it plays an important role 

in both flood protection and the salt water intrusion control network of southern 

Dade County (Fig. 1). 

The Mowry Canal is of special interest to Biscayne National Park because its 

annual discharge is generally the greatest of the three major water management 

canals that discharge into southern Biscayne Bay (Fig. 2). Mean annual discharges 

for water-years 1975-1980 (Oct 1 - Sep 30) were recorded as 162,234 acre-feet for 

the Mowry Canal, 137,731 acre-feet for the Snapper Creek Canal (C-2), and 

106,584 acre-feet for the Black Creek Canal (c-1) (WY 1978 is omitted since 

discharge data for that year are not available for the Black Creek Canal). 

Typically, the combined discharge from these three canals was greater than 

400,000 acre-feet per year during the period of this study. 

The objectives of this report are to assess the water quality of the Mowry Canal 

and to quantify its freshwater discharge into Biscayne Bay. This study provides 

necessary groundwork for future studies designed to assess the impact of freshwater discharge on the marine habitat of the Biscayne Bay portion of Biscayne 

National Park. 

To accomplish the above mentioned objectives this study analyzed available water 

quality data from county and federal networks for the period 1974-1981. Trends in 

water quality parameters are further related to 1980 Mowry Canal basin land use 

data provided by the Metropolitan Dade County Planning Department. The 

relationship between rainfall in the Mowry Canal basin and discharge from this 

canal to Biscayne Bay is also discussed. 

Basin Description 

The Mowry Canal is located in southern Dade County near Homestead, Florida. Its 

major branch, C-103, extends approximately 18.6 miles from the L-31N canal east 

and south to Biscayne Bay where it discharges just north of Convoy Point (Fig. 3). 

C-103s is a 2.3 mile section extending south from C-103 between Homestead and 

Florida City. A second extension, C-103N, extends 6.2 miles north and west from 

the main branch. 

The 27.1 mile Mowry Canal system drains a 49.3 square mile basin, roughly bounded 

on the west by the L-31N Canal, on the east by SW 137th Avenue and Homestead 

Air Force Base, on the north by SW 200th Street, and on the south by SW 328th 

Street. 

Agriculture accounts for 51.5 percent of land use in the Mowry Canal basin, with 

22.3 percent of the basin in vegetables or row and field crops, 20.2 percent of the 

basin in groves, 2.3 percent occupied by plant nurseries, and other agricultural uses 

accounting for 6.7 percent of the basin land use. Residential uses contribute 

14.9 percent of basin land use, of which 11.7 percent is single family housing with 

3.2 percent representing other residential uses. Seventeen point seven percent of 
Figure 1. Major canals and canal basin delineations for southeastern Dade 

County, Florida. 
- Mowry Conol uSGS 02

.. --- Snopper Creek Conol 

. . . . . . . . . Block Creek Conol US

WATER YEAR 

Figure 2. Annual discharge from Mowry Canal, Snapper Creek Canal, and Black Cree

years 1975-1980. 
C

C-103 MONITORING STATIONS: 

0 DADE COUNTY DERM 

USGS 02290725 

@ HOMESTEAD EXPERIMENTAL STATION 

( 

SOUTH FLORIDA WATER M/NAGEMENT 

DISTRICT- CANAL CONTROL STRUCTURES 0 I 

c?:? e.:d C-I03 BASIN LIMITS I 

Figure 3. The Mowry Canal (C-103) Basin. 
the basin is undeveloped; transportation, communication, and utilities together 

account for 9.1 percent; and the remaining 6.8 percent of the basin land use is 

divided among parks and open space, inland water, and commercial, industrial, and 

institutional uses (Table 1). 

The South Florida Water Management District operates five control structures in 

the Mowry Canal system. Control structures 20 F, 166,167, and 179 are reinforcedconcrete, U-shaped spillways provided with vertical gates installed on crests of 

trapezoidal weirs. These structures are operated by automatic controls with 

opening and closing determined by headwater elevation. All are located on the 

major branch of C-103, except S-166 which is located on C-103N (Fig. 3). Their 

function is to maintain water level control in C-103 and C-103N. Control 

structure 196 is a gated concrete culvert near the western end of C-103 which is 

operated manually. It controls water flow to the east when required. S-20F, 

located near the Mowry Canal mouth, helps to maintain salinity control for the 

system. 

Rainfall - Discharge Analysis 

Monthly rainfall in the Mowry Canal basin is represented by rainfall at the 

Homestead Experiment Station (NOAA 1975-1981) (Fig. 4). Monthly rainfall for 

water-years 1975-1981 ranges from a low of 0.12 inches in April of 1975 to a high 

of 27.3 inches (associated with Tropical Storm Dennis) in August 1981. Mean 

monthly rainfall for the period of study (Fig. 5a) indicates that August is the 

wettest month with a seven-year monthly mean of 12.4 inches, followed by 

September, May, and June with means of 11.6 inches, 8.9 inches, and 8.6 inches, 

respectively. The driest month was March, with a seven-year monthly mean of 

only 1.2 inches, followed by January, December, and November with means of 1.4 

inches, 1.9 inches, and 2.6 inches, respectively. Annual rainfall measurements 

range from a low of 49.6 inches in water-year 1975 to 81.0 inches in water-year 

1981 (Fig. 6). 

Discharge data were collected at a United States Geological Survey (uSGS) 

continuous monitoring station, USGS 02290725, located near the Mowry Canal 

mouth. Monthly discharge (Fig. 4) from water-year 1975 through water-year 1981 

ranged from zero, occurring 10 times, to 54,650 acre-feet, associated with Tropical 

Storm Dennis in August of 1981. September was the month with the greatest mean 

monthly discharge (29,882 acre-feet), followed by August, October, and June with 

seven-year mean monthly discharges of 26,278 acre-feet, 21,855 acre-feet, and 

19,929 acre-feet, respectively (Fig. 5b). The lowest mean monthly discharge 

occurred in April with a seven-year monthly mean of 4,042 acre-feet, followed by 

March, February, and January with means of 4,875 acre-feet, 7,434 acre-feet, and 

8,403 acre-feet, respectively. Annual discharge ranged from a minimum of 131,792 

acre-feet in water-year 1975 to a maximum of 243,250 acre-feet in water-year 

1978 (Fig. 6). 

A positive relationship between rainfall and discharge is suggested by monthly, 

mean monthly, and annual measurements. Correlation coefficients were computed 

by the least-squares method to determine the strength of the relationship between 

rainfall within the Mowry Canal basin and discharge from the Mowry Canal. 

Analysis between mean monthly rainfall at Homestead Experimental Station and 
Table 1. Land use in the Mowry Canal (C-103) Basin. 

Land Use 

Agriculture 

Row and field crops, vegetables 

Groves 

Pland nursery 

Other. agriculture 

Undeveloped 

Residential 

Single family 

Other residential 

Transportation, communication, and 

utilities 

Inland water 

Commercial and industrial 

Parks and open space , 

Institutional 

Total 

Percent of Canal Basin Acreage 

Compiled from 1980 land use information provided by the Metropolitan Dade County Planning 

Department. 
3 - Monthly Discharge of Mowry Canal (C-103) at USGS 02290725 

Figure 4. Monthly discharge from the Mowry Canal and monthly rainfall within the 

Basin. 
Figure 5a. Mean monthly rainfall at Homestead Experimental Station from 

water years 1975-198 1. 

r JFMAMJJASOND 

1% 

Figure 5b. Mean monthly discharge at Mowry Canal (USGS 02290725) from 

water years 1975-1981. 
RAINFALL 

DISCHARGE 

1300 

WATER YEAR 

Figure 6. Annual rainfall at Homestead Experimental Station and annual discharge (USGS 02290725) from Mowry Canal (water years 1975-198 1). 
,mean monthly discharge at USGS 02290725 (Fig. 7a) gave a correlation coefficient 

of 0.72, which is significant (p(.005). A better fit is obtained if mean monthly 

discharge is lagged one month after mean monthly rainfall (Fig. 7b). This analysis 

results in a correlation coefficient of 0.89, which is also significant (p<.0005). The 

stronger relationship between rainfall and runoff with a lag time is likely the result 

of water management detention practices within the Dade County canal system. 

METHODS AND ANALYSIS 

Water Quality Evaluation 

Mowry Canal water quality data for various physical parameters, nutrients, bacteria, metals, and pesticides were analyzed. Data were available from two 

sources. The United States Geological Survey had conducted extensive water 

quality sampling at a location near the Mowry Canal mouth (USGS 02290725) 

(Fig. 3). From October 1975 to July 1980 over 105 parameters, including physical 

parameters, ions, nutrients, metals, pesticides, and sediments were analyzed with 

irregular frequency. Those parameters of interest to this study include pH value, 

specific conductance, dissolved oxygen, alkalinity, ammonia nitrogen, nitrate + nitrite nitrogen, total nitrogen, total organic nitrogen, and total phosphorus. Water 

samples were taken at depths of 0.5 foot or 1.0 foot below the water surface. 

Analyses of these water samples were accomplished by the USGS according to 

analytical methods published in Methods for Determination of Inorganic Substances 

in Water and Fluvial Sediments (USGS1979)and~;thods -- for the Analysis 

of Water - and Wastewater (APHA 1979). The results of these analyses were 

provided to the National Park Service for analysis in the form of a WATSTORE 

data retrieval. 

The Metropolitan Dade County Department of Environmental Resources Management (DERM) has also conducted extensive water quality sampling in the Mowry 

Canal system. Four sampling stations are located in this canal system as a part of 

their Canal Monitoring Program. This sampling program is designed to present an 

overview of water quality for the county's major surface water systems via 

monthly sampling and analysis of general physical and chemical parameters 

(Labowski 1982). Samples taken at station 41 (Fig. 3), located in the western reach 

of C-103, are intended to represent background conditions. Samples from station 

40, located on C-103N, and station 39, located just downstream from the junction 

of C-103N and C-103, are intended to be representative of mid-canal conditions. 

Samples from station 38, located about two miles upstream from the Mowry Canal 

mouth, are intended to be representative of the quality of inland water discharged 

to Biscayne Bay. 

From January 1980 through December 1981 Dade County DERM sampled monthly 

nine general physical and chemical parameters. The parameters of interest to this 

study include water temperature, dissolved oxygen, conductivity, Secchi disc 

transparency, nitrite + nitrate nitrogen, total colif orm bacteria, fecal coliform 

bacteria, and fecal streptococcus bacteria. All samples were taken at mid-depth in 

the water column. Over the 24-month period this corresponds to an average 

sampling depth of 5.9 feet at station 38, 5.0 feet at station 39, 3.5 feet at station 

40, and 3.5 feet at station 41. Bacteriological analyses were performed by the 
01 I I I I I I I I I I I I I 

0 12345678910111213 

Tt MONTHLY RAINFALL (INCHES) 

Figure 7a. Relationship between mean monthly rainfall at Homestead 

Experimental Station and mean monthly discharge from Mowry Canal 

(USGS 02290725). 

X MONTHLY RAINFALL (INCHES) 

Figure7b. Relationship between mean monthly rainfall at Homestead 

Experimental Station and mean discharge from Mowry Canal (USGS 

02290725) one month later. 

C 
,State of Florida Department of Health and Rehabilitative Services laboratory, 

employing standard methodology to determine most probable number (MPN) per 

100 milliliters (APHA 1979). Chemical analyses for nutrients were performed in 

the DERM laboratory with an autoanalyzer within the maximum allowable storage 

time established by the USEPA and using methods that recommended in Standard 

Methods (APHA 1979). The results of these analyses were provided to the National 

Park Service by Dade County DERM in the form of a computer printout. 

Two different statistical analyses were performed on these data. A one-way 

analysis of variance (ANOVA) was performed in order to determine whether site 

means could have been obtained from populations with the same parametric mean. 

Stated differently, is there variance among sites in addition to the within-site 

variance? Parameters evaluated included: temperature, dissolved oxygen, conductivity, secchi disc transparency, and nitrite + nitrate nitrogen. Calculations were 

performed by a standard Statistical Package for the Social Sciences (SPSS) 

computer program. When the ANOVA resulted in rejection of the null hypothesis 

(therefore, site does affect parameter concentration), the Student-Newman-Keuls 

multiple range test was applied in order to determine between which sampling 

stations the significant difference existed (Zar 1974; Sokal and Rohlf 1969). The 

second statistical analysis performed was a two-way ANOVA with site and date 

being the two main effects. Calculations were performed by an SPSS computer 

package program. 

ANOVA assumes independent observations which are random samples from normally distributed populations with equal variances. In the present situation the 

assumption of independence is violated, as is typically the case in the monitoring of 

a water quality parameter over time. The random sampling assumption is also 

violated with respect to both site and date, since sampling is performed at regular 

time intervals at sites which were not randomly selected. Since no replications 

were performed, the two-way ANOVA requires the additional assumption of no 

interaction between main effects. 

In all cases where the ANOVA resulted in rejection of the null hypothesis, the 

probability of rejecting the null hypothesis when it should not be was very low 

(always less than 0.001). Moreover, in all cases the conclusions reached by the oneway ANOVA and the two-way ANOVA were identical, and the significance levels 

were very close. It is felt that although the randomness and independence 

assumptions are violated, the conclusions reached are valid. The results of these 

statistical analyses are presented here for descriptive purposes. The significance 

levels reported are those for the one-way ANOVA. 

Physical Parameters 

Physical parameters, such as water temperature, dissolved oxygen, specific conductance, pH value, alkalinity, and Secchi disc transparency, are commonly 

determined on water samples in order to partially define the water quality 

character of a freshwater system and determine its suitability for aquatic life. 

Water temperature, dissolved oxygen, and pH value are particularly important in 

assessing the ability of an aquatic habitat to support diverse aquatic communities. 

High water temperatures, low dissolved oxygen concentrations, low pH value, or 
abnormally extreme fluctuations in any of these parameters have been shown to 

cause decreased species diversity, signaling an unhealthy aquatic environment. 

Specific conductance is a measure of the resistance of a solution to electrical 

current and, therefore, an indicator of the ionic content of water. Previously, this 

parameter has been shown to be an early indicator of changes in water management practice and water quality in non-urban areas of southern Florida (Flora and 

Rosendahl 1981). Large fluctuations in specific conductance that cannot be 

accounted for by seasonal variability may indicate movements of agriculturally 

influenced water through the southern Florida system and a need for expanded 

water quality monitoring. 

Alkalinity is a measure of the buffering capacity of a water ,system to resist wide 

scale variations in pH value. This capacity is especially important in areas where 

acid precipitation presents a major threat to aquatic resources. 

Secchi disc transparency is defined as the mean depth where a weighted white disc 

of standard diameter (20 cm) disappears when viewed from the shaded side of a 

vessel, and that point -where it reappears upon raising it after it has been lowered 

beyond visability (Wetzel 1975). As such, it is an indicator of water clarity and is 

influenced directly and indirectly by many factors, including algal productivity, 

turbidity, water color, and visual acuity of the observer. 

Monthly mid-depth water temperature measurements from January 1980 through 

December 1981 were available for the four DERM stations located in the Mowry 

Can$ system (vg. 8). Water temperature over this two year period ranged from 

16.0 C to 31.5 C and displayed a seasonal trend. Lowest water temperatures 

generally occurred in December or January, and highest water temperatures 

usually were recorded in June or July. 

Monthly water ternperatures did not display significant (p;+ 0.75) variability among 

the four stations and were similar to those 'occurring in other canal systems 

throughout Dade County. No point source thermal discharges are known to occur 

in the Mowry Canal system, and the water temperatures are within the tolerances 

of fish species commonly found in southern waters. 

Dissolved oxygen data from the four DERM stations and the USGS station at the 

mouth of the Mowry Canal are presented in Table 2 and Figure 9. Dissolved oxygen 

concentrations in natural systems have been described by a number of mathematical models generally based upon the equation of continuity and the conservation of mass (Waite and Freeman 1977). One common dissolved oxygen model 

states that dissolved oxygen concentration in an open channel flow system depends 

upon the initial concentration of dissolved oxygen, the rate of atmospheric 

reaeration, the biochemical oxygen demand, and plant photosynthesis and 

respiration. 

In the Mowry Canal system, low dissolved oxygen concentrations were found to 

occur at the westernmost station, DERM station 41 (p4.0.0001). Pissolved oxygen 

concentrations at this station ranged from 1.0 mg 1- to 6.8 mg 1- with a mean of 
Table 2. Mean, standard deviation and range of selected physical parameters in the Mowry 

Canal during period of study. 

Dissolved oxygen (mg cl) 

Station Period of record n x SD Min Max 

DERM 38 

DERM 39 

DERM 40 

DERM 41 

USGS 02290725 

DERM 38 

DERM 39 

DERM 40 

DERM 41 

USGS 02290725 

USGS 02990725 

USGS 02990725 

DERM 38 

DERM 39 

DERM 40 

DERM 41 

Specific conductance (urnhos cm-') 

pH (units) . 

1975-1980 30 7.4 - 

Alkalinity (mg 1-I as CaC03) 

Secchi disc transparency (m) 
1211~"1~11~11111111111111 

JFMAMJ JASOND J F M A M J J A S O N D 

1980 1981 

Figure 8. Water temperature (OC) at sampling depth at DERM Mowry Canal 

stations 38-41 (1980-1981). 

32- - DERM 

30 - 

*--a DERM 

" 0 28- 

V 0 

y 26- 

3 

p 20 \o 

E 

w 18 

I16- 

14 

12 

- 

- 

li""""lllllllllllll 

JFMAMJJASONDJFMAMJ JASOND 

1980 1981 
, ?.4 mg I-' (Table 2). These concentrations fell below Dade County's 4.0 mg 1- 

minimum dissolved oxygen standard for 16 of the 20 samples taken from January 

1980 through December 198 1. 

The cause of the low dissolved oxygen concentration at station 41 and also at the 

westernmost stations of the C-4, C-I, and C-102 canals is not fully understood. 

However, all these canals begin at a junction with the L-31N canal, where it is 

speculated that low dissolved oxygen concentrations are due to the inflow of poorly 

oxygenated groundwater into the relatively deep L-31N canal. 

As the canal water flows eastward it reaerates. Dissolved oxygel concentration? 

at DERM stations 38 trld 40 were siyilar with meanf of 5.7 mg 1- land 5.4 mg 1- 

and ranges of 2.8 mg 1 to 8.1 mg 1 and 3.5 mg 1- to 10.8 mg I- , respectively. 

Dissolved oxygen concentrations at these stations generally met Dade County's 

mimimum standard except for brief periods occurring between September and 

December (Fig. 9). 

DERM station 39, located just past the junction of C-103 and C-103N, displayed 

significantly high difsolved oxygen concentrations (p <0.0001) with a mean concentration of 8.0 mg I- . No reason is presently known for these high concentrations. 

Dissolved oxygen concentrations at the U2GS station from 1975-1980 were also 

found to be higher with a mean of 6.4 mg I- . 

Specific conductance data from the USGS station and the four Dade County DERM 

stations are presented in Table 2 and Figures 10 and 11. Overall characteristics 

show stations 39, 401and 41 to be similar with mean ppecific conductance ranging 

from 581 umhos cm- at station 39 to 661 umhos cm- at-?tation 41 with individupl 

readings predominantly falling between 400 umhos cm and 800 umhos cm- . Station 38 differs signiycantly (p (0.001) from this with a mean specific fonductance of 959 umhos cm- , ranging from 575 umhos cm- to 3200 umhos cm- . The consistantly higher specific conductances observed at station 38 (Fig. 11) were 

due to its proximity to Biscayne Bay and the occasional backflow of brackish 

water. Over the 1980- 198 1 county sampling period, the highest conductivity 

reading observed at station 38 occurred during a four month period (summer of 

1981) of zero discharge from Mowry Canal. Pre-1980 conductivity data from the 

USGS sampling station near the mouth of F-103 also reflect thelslight intrusion of 

saltwater, rangpg from 575 umhos cm- to 1580 umhos cm- with a mean of 

843 umhos cm . Dade County DERM data shows that elevated conductivity 

readings are also observed at the sampling sites nearest Biscayne Bay in other 

county canals. (DERM, unpublished Canal Monitoring Program data.) 

Alkalinity and pH value data are available only from the USGS monitoring station 

from 1975-1980 (Fig. 12a and 12b, Table 2). pH value determinations all fal! 

within a range of 7.0 to 8.1 and have a mean of 7.4. Mean alvlinity is 200 mg 1- 

with a relatively narrow range of 166 mg 1- to 233 mg 1- . These pH value 

measurements and alkalinity concentrations are common throughout southern 

Florida and result from close contact with a predominantly calcium carbonate 

lithology. 

Secchi disc transparency data are available from the four DERM stations (Table 2, 

Fig. 13). Secchi disc depths at stations 38, 39, and 40 were all similar, ranging 
12 - X-5.4 mg/~ DERM 40 

10 - 

8 - 

6 - 

- 2- -

- 2- 

\ \ 

CT CT 

5 0-11111111111"111111111 -0 E IIIIIIIIII

z JFMAMJJASONDJFMAMJJASONO z JFMAMJJASON

W 1980 1981 1980 

W 

? a 

> 

X X 

0 0 

Figure 9. Dissolved oxygen concentration (mg I-') at DERM Mowry Canal sampling station

1 Note: Spaded areas indicate those times when dissolved oxygen concentra

4.0 mg 1- Dade County standard. 

0 0 

W 

3 l2 

% 

l0- 0 

8 

6- 

2- 

0 I'lI'lI1llIII1lIrII1lI 0 IIII'I1'II

JFMAMJJASONDJFMAMJJASOND JFMAMJJASOND 

1980 1981 1980 

- 3-3.4 mg/1 DERM 4 1 

- 

W* 

3 12- 

z 

5 10- 0 

'is 5.7 mg/~ 
DERM 40 

2Or P = 645 P~~OS cmDERM 41 

P = 661 pmhos cm-I 

n = 23 

DERM 

K = 581 

20[ n=23 

DERM 38 

i( = 959pmhos cr

n= 23 

Figure 10. Specific conductance distribution (4 mhos cm-' ) at DERM Mowry Canal s

38-41 (1980-1981). 
Y 

W 

0 

Z 2 200 

0 

3 

0 

Z 

O 0 IOC 

0 - 

Lr, 

G 

W 

a. 

m 

- DERM 38 

--- DERM 39 

llllllllIlllll11~I1I1I11 

J FMAMJ JASON0 JFMAMJJASOND 

Figure 11. Specific conductance distribution (4mhos cm-l) at DERM Mowry 

Canal sarnpling stations 38 and 39 (1980-1981). 
ALKALINITY (mg/ l as CoC03) 

Figure 12a. Alkalinity distribution (mg 1-I as CaC03) at USGS Mowry Canal 

station 02290725 (1975-1980). . 

I' I - I sc4,,,4 

rc'rc'r-'rc'F;, 

pH (UNITS) 

Figure 12b. pH distribution at USGS Mowry Canal station 02290725 (1975-1980). 

from 0.9 to 3.8 m. Mean secchi disc depths were 2.1 m at station 38, 2.5 m at 

station 39, and 2.1 m at station 40. Secchi disc transparency at station 41 was 

significantly (p <0.0001) lower with a mean of 1.1 m, and ranging from only 0.1 m 

to 1.8 m. The reason for the reduced transparency at station 41 is not known, 

although reduced transparency is also found in other county canals at DERM 

sampling stations near L-31N. (DERM, unpublished Canal Monitoring Program 

data.) 

Nutrients 

Nitrogen 

Nitrogen occurs in freshwater systems in several forms: dissolved molecular N 2' ammonia (NH3), nitrite (NO -), nitrate (NO3-), and numerous organic forms. 

Sources of this nitrogen inclu3e precipitation, nitrogen fixation both in the water 

and sediments, and inputs from surface and groundwater drainage. Nitrogen loss 

may occur by effluent outflow from the system, reduction of NO3- to N2 by 

bacterial dentrifitation with return of N2 to the atmosphere, or permanent loss of 

inorganic or organic nitrogen compounds to the sediments. The nitrogen cycle in 

freshwater systems is essentially microbial. Bacterial oxidation and reduction of 

nitrogen compounds are coupled with photosynthetic assimilation and utilization by 

algae and aquatic plants (Wetzel 1975). 

Nitrite and nitrate nitrogen data are available for the four DERM stations and the 

USCS station in* the Mowry Canal (Table 3). Nitrite plus nitrate nitrogen 

concentrations at the westernmost DFRM station 41 were significantly low 

(p(0.0001) with a mean of 0.09 mg 1- (Fig. 14). These levels of NO +NO 

nitrogen are similar to those reported for Conservation Area 3A (Millar 19d) and 

the Shark River Slough of Everglades National Park (Flora and Rosendahl 1982) 

where rapid uptake by biological communities generally keeps nutrient levels low. 

Low N02+N03 nitrogen concentrations are also reported by Dade County DERM 

for the westernmost stations in the C- 1, C- 102, and C- 11 1 canals (Fig. 15). 

In contrast, N02+N03 nitrogen concentrations at DERM station 40, focated in 

C-103N, were s~gnificantly high (p (0.0001) with a mean of 4.25 mg I- . Nitrate 

concentrations at this DERM station were the highest reported at any of the 47 

stations monitored by the Dade County Canal Monitoring Progra~ (Fig. 15). Thesle 

high N02+N0 nitrogen concentrations (ranging from 1.05 mg 1- to 8.30 mg 1' ) 

indicate a ma&edly degraded water quality at this site, and are probably related to 

land use which is a combination of residential and agricultural. They may result 

from the application of fertilizers which contain nitrogen in the form of either 

ammonia or nitrate. 

Orth (1976) found high levels of nitrate in the top portion of groundwater sampled 

from wells in thelMowry Canal basin. He found nitrate nitrogen concentrations 

averaging 3 mg 1- or less in groundwater under t~pical agricultural areas over a 

two year period, with concentrations over 10 mg I- occurring in some wells from 

time to time. Major factors influencing nitrate levels appeared to be generous 

application of fertilizers, maintenance of fallow land, and leaching due to excess 
Table 3. Mean, standard deviation and range of nutrients in the Mowry Canal during period 

of study. 

NO2 + NO3 - Nitrogen (mg I-') - Station Period of record n x SD Min Max 

DERM 38 1980-1981 20 1.13 0.41 0.33 2.01 

DERM 39 1980-1981 19 1.69 0.90 0.05 3.80 

DERM 40 1980-1981 20 4.25 1.80 1.05 8.30 

DERM 41 1980-198 1 19 0.09 0.08 0.03 0.40 

USGS 02290725 1975-1980 28 0.87 0.31 0.18 1.30 

NH3 - Nitrogen (mg I-') 

USGS 02290725 1975- 1980 32 0.05 0.06 0.02 0.30 

Total Organic Nitrogen (mg 1-l) 

USGS 02290725 1975- 1980 32 0.30 0.17 0.12 0.76 

USGS 02290725 

USGS 02290725 

Total Nitrogen (rng I-') 

1975- 1980 28 1.24 

Total Phosphorus (mg 1-I) 
ji= 4.25 mg/l DERM 40 

n 

- 

Si=0.09 mg/l DERM 41 I 

9 

8 

2 - 

' 

1 JFMAMJJASONDJ F

- 

- x = 1.69 mg/l 

L 

I 

Figure 14. Nitrite plus nitrate concentration (mg 1-l) at DERM Mowry Canal sampli

(1980-1981)- 

- 

o'~IIIImIw . .. JFMAMJ JASONDJFMAMJ JASONC 

1980 1981 
O DADE COUNTY DERM CANAL 

MONITORING PROGRAM STATIONS 

Figure 15. Mean nitrate concentration (mg I-') at selected Dade County DERM 

Canal Monitoring Program stations (1980-1981). 
.irrigation or rain. Nitrite plus nitrate nitrogen concentrations of this magnitude 

are a concern as they degrade canal and groundwater quality and may be 

responsible for increased nitrogen loading at the outfall to Biscayne Bay, possibly 

influencing marine water quality. 

Nitrite plus nitrate nitrogen concentrations at station 39, located just below the 

junction of C-103 and C-103N, were lower than those in C-103N with a mean of 

1.69 mg 1- . This decrease is probably brought about by dilution of the highly 

enriched C-103N water with the C-103 water. A mean N02+N03 nitrogen 

concentration of 1.69 mg 1- , however, is still considered excessive and is a cause 

for concern. 

Further downstream at DERM station 38 N02+N0 nitrogen concentrations were 

lower still, with a mean of 1.13 mg 1- , agaln pro%ably a function of biological 

uptake and dilution. 

Utilizing the long term (1975-1980) data available for the USGS station at the 

mouth of the Mowry Canal (Fig. 16b), it can be seen that relatively high N02+N03 

nitrogen concentrations have occurred thrfughout the period of record at the 

discharge point of the canal (T = 0.87 mg 1- 1. The biological significance of this 

nitrogen loading is not known but warrants further study. 

Ammonia nitrogen, total organic nitrogen, and total nitrogen have been measured 

only at the USGS station near the mouth of the Mowry Canal (1975-1980). 

Figure 16a shows't~at the ammonia nitrogen concentration~~were low, ranging from 

0.02 to 0.30 mg I- with a six year meal of 0.05 mg 1- , well below the Dade 

County surface water standard of 0.5 mg 1- . 

Total orgapic nitrogen concentrations were also low, ranging from 0.12 mg 1-I to 

0.76 mg I- with a mean of 0.30 mg 1-I (Fig. 17a). Total nitrogen concentrations, 

the sum of the ammonig, nitrite, nitra e, and total organic nitrog~ concentrations, f: ranged from 0.51 mg 1- to 1.80 mg 1- with a mean of 1.24 mg 1- (Fig. 17b). 

It should be noted again that ammonia-nitrogen and total nitrogen data are only 

available for the USGS station near the Mowry Canal mouth, and the low 

concentrations reported are indicati-~e of the canal only at that point. No data are 

available for ammonia or total nitrogen concentrations elsewhere in the Mowry 

Canal system. 

Phosphorus 

No other element in freshwater systems has been as extensively studied as 

phosphorus since it is phosphorus which most commonly limits biological productivity. The chemistry of phosphorus in freshwater systems is complex, and phosphorus 

may occur in several different forms. Soluble orthophosphate is readily assimilated 

biologically. Phosphorus is also found in dissolved organic forms and suspended 

organic forms. Phosphorus may also be found trapped in sediments where it may be 

released to the water column under suitable conditions. The most important 

quantity, in view of the metabolic characteristics of a freshwater system, is the 

total phosphorus content of unfiltered water, which consists of the phosphorus 

suspended in particulate matter and dissolved phosphorus (Juday 1927). 
Figure 16a. Ammonia nitrogen concentration (mg 1-I) at USGS Mowry Canal 

station 02290725 (1 975-1 980). 

Figure 16b. Nitrite-nitrogen + nitrate-nitrogen concentration (mg 1-l) at USGS 

Mowry Canal station 02290725 (1 975-1 980). 
Figure 17a. organic nitrogen concentration (mg I-') at USGS Mowry Canal 

station 02290725 (1975-1980). 

Figure 17b. Total nitrogen concentration (rng I-') at USGS Mowry Canal station 

02290725 (1975-1980). 
Total phosphorus data in the Mowry Canal system were available only for the USGS 

sampling station near the canql mouth (Fig. 118, Table 3). Concentrations pere not 

high, ranging from 0.01 mg 1- to 0.04 mg I- pith a mean of 0.014 mg I- . These 

concentrations, generally less than 0.02 mg I- , are indicative of uncontaminated 

water and indicate that phosphorus enrichment is not a problem in the Mowry 

Canal system. Available data indicate that phosphorus concentrations throughout 

Dade County canals are typically low. 

Bacteria 

Pollution of aquatic systems by the excreta of warmblooded animals creates public 

health problems for man and animals, and potential disease problems for aquatic 

life (USEPA 1976). Most freshwater systems naturally contain microbes, which 

may or may not be pathogenic. Pathogenic bacteria in water bodies originate from 

several sources, including stormwater runoff, agricultural runoff, domestic sewage, 

and wildlife. Certain non-pathogenic organisms, such as coliform bacteria and 

fecal streptococci bacteria, are used as microbiological indicators of pathogens in 

water in order to assess the suitability of a water for aquatic life or for drinking or 

swimming. 

Coliform bacteria are the most commonly used microbial indicators of water 

quality. The total coliform group includes species af bacteria which occur in the 

gut of warmblooded animals as well as species which occur naturally in soils. Most 

species of fecal coliform bacteria, a portion of the total coliform group, are 

restricted to the guts of warmblooded animals. The presence of fecal coliform 

bacteria indicates a degradation of water quality and a relative risk of disease 

hazard. Fecal streptococci bacteria are found in greater numbers within the 

intestines of warmblooded animals other than humans. 

Data for total coliform bacteria, fecal coliform bacteria, and fecal streptococci 

bacteria were available from the four Dade County DERM Mowry Canal sampling 

stations. Total coliform (TC) bacteria (Fig. -19) generally met Dade County's 

standard of 1000 (MPN) per 100 ml. The maximum standard was exceeded once at 

stations 39 and station 41, three times at station 38, and four times at station 40. 

The Dade County standard for fecal coliform (FC) bacteria is 200 (MPN) per 

100 ml. In general, all four Mowry Canal sites met this standard as well (Fig. 20). 

Levels exceeding the FC standard were detected one time at station 41, and two 

times at stations 38, 39, and 40. Bacteriological counts for those instances where 

either the total coliform standard or the fecal coliform standard was exceeded are 

presented in Table 4. 

The data do not indicate any clear differences in bacteriological counts among 

Mowry Canal sampling stations, and in general, bacterial contamination in this 

canal system does not appear to be a problem. Comparison of bacteriological 

counts in the Mowry Canal to bacteriological counts in other county canals 

monitored by the DERM Canal Monitoring Program reveal that bacteriological 

counts in the Mowry Canal system were the lowest of the 16 canals monitored from 

1980 to 1981. 
40- 

30 - 

. 

20 - 

MJS 

Figure 18. Total phosphorus concentration (mg 1-I) at USGS Mowry Canal 

station 02290725 (1975-1980). 
b 

JFMAMJ JASONDJFMAMJ JASON0 

3000 

. J 

- DERM 41 

3000 - 

3000 

1980 1981 1980 

Ir Figure 19. Total coliform bacteria (MPN 100 ml-l) at DERM Mowry Canal sam

(1 980-1 98 1). 

- 
12oot DERM 40 1 

JFMAMJJASONDJFMAMJJASOND 

1980 1981 

JFMAMJJASOND

1980 

Figure 20. Fecal coliform bacteria (MPN 100 rnl-l) at DERM Mowry Canal samplin

(1980-1981). 

1400 

1200 

- 1000- 

E 

800- 0 - 

\ 

600- 

r 

- DERM 41 

400 - 

200 - 

J F M A M J J A S O N D J FMAMJ JASON0 JFMAMJJASOND

1980 1981 1980 
Table 4. Bacteriological counts for DERM stations exceeding total coliform 

standard of 1000 MPN/100 ml or fecal coliform standard of 

200 MPN/100 ml. 

Total Fecal Fecal 

Coliforms Coliforms Streptococci 

(~~~1100 ml) (MPN/~OO ml) (MPN/~OO ml) 

Station 40 

March 1980 

June 1980 

December 1980 

Station 41 

June 1980 

July 1981 

Station 39 

June 1980 

November 1980 

September 1981 

Station 38 

March 1980 

August 1981 

December 198 1 

NA = Not available 
Heavy Metals and Pesticides 

A limited number of heavy metal determinations in the water column and bottom 

sediments, as well as pesticide determinations on 21 compounds in the bottom 

material, were completed by the USGS at the Mowry Canal mouth (USGS 02290725) 

on an irregular basis from 1975-1980 . The results of these samplings are presented 

in Table 5 (heavy metals in water), Table 6 (heavy metals in bottom material), and 

Table 7 (pesticides in bottom material). 

Because of the limited amount of data available for both metals and pesticides, a 

definitive analysis is not attempted. However, the presence of several metals in 

the water column and bottom materials is noted. In addition, DDT and its 

breakdown products, polychlorinated biphenyls (PCBs), chlordane, and dieldrin, 

were all detected at the Mowry Canal mouth during the period of this study. 

An important point to note is that agriculture is the predominant land use in the 

Mowry Canal basin. While many pesticides or herbicides are used for agriculture, 

mosquito control, and aquatic plant control throughout the basin, little is known 

about the amounts or the environmental fates of the metals and pesticides applied 

for these purposes. Table 8 lists some of the pesticides commonly used on crops in 

Dade County. No local studies or monitoring activities currently exist that 

quantify the runoff of these materials within the basin or their possible impact 

upon entry into Biscayne Bay. 

SUMMARY AND CONCLUSIONS 

Analysis of available discharge data indicates that from water-year 1975 to wateryear 1980 the Mowry Canal discharged an average of 162,234 acre-feet annually, 

probably more than any other canal discharging into southern Biscayne Bay. 

A significant relationship was found to exist between mean monthly rainfall at 

Homestead Experimental Station and mean monthly discharge from the Mowry 

Canal over the period of this study. A stronger relationship was found if mean 

monthly discharge was lagged one month behind mean monthly rainfall, possibly 

due to water management practices within the Dade County canal system. 

Water quality data available from the Dade County Department of Environmental 

Resources Management and the United States Geological Survey indicate that the 

water quality of the Mowry Canal appears to be relatively good. Among the four 

DERM stations in the Mowry Canal system, water temperatures did not display 

significant areal variability, and temperatures were within tolerances of native fish 

species. Dissolved oxygen concentrations at DERM station 41 werf significantly 

lower than at the other stations, generally less than the 4.0 mg 1- Dade County 

surface water standard, possibly due to the inflow of poorly oxygenated groundwater near L- 31N. Dissolved oxygen concentrations at station 39 were significantly higher than at the other stations for an unknown reason. Specific 

conductance at station 38, near Biscayne Bay, was significantly higher than more 

inland sites due to the occasional backflow of brackish water. Secchi disc 

transparencies were similar at all DERM stations with the exception of station 41, 

where clarity was significantly reduced for an unknown reason. Alkalinity 
Table 5. Heavy metal concentrations (water column) in Mowry Canal at S-20F (USGS 02290725). 

- - 

Total DIS TR DIS TR DIS TR DIS TR TR DIS 

01002 01040 01027 01046 01045 01049 01051 01056 01055 01067 0108

ug 1- 1 1 

ug 1- ug 1-I ug 1-l ug 1-l ug 1-I ug1- ug1-I ug1-I ug1-I ug1-I 

1 

31 Oct 75 

23 Jan 76 

26 Apr 76 

30 Nov 76 

14 Apr 77 

19 Oct 77 

04 Apr 78 

05 Mar 79 

20 Jun 79 

06 Mar 80 

22 Jul 80 

ND = Not detected 

DIS = Dissolved 

TR = Total recoverable 

Total = Total 

Data provided by USGS via WATSTORE data retrieval 
Table 6. Total heavy metal concentrations in bottom material in Mowry Canal at 

S-20F (USGS 02290725). 

23 Jan 76 5 10 10 1100 10 50 10 

14 Apr 77 4 10 10 500 20 10 10 

Data provided by USGS via WATSTORE data retrieval 
4 C 

ZG-"" 

C 

0 h 

'- 00 9R 

G" 

x4 

W Q 

> h 

r=cn 

LA m 

7 2 

'2 h 

3- % 

N 

a;? 

< & 

W(*\ 

C 

2.2 4 

55% 

Q) den 

Z kim 

a 

c 

04 

.5 h 

N- 

.! % 

a 

C 

.3 4 

.c 3 

a 

5 

-4 4 

L m 2 2 .-.( 

(d '*\ 

Z 

a\ m 4 

U- 

&% 

ooq 

I I NO 

m3nW 

N4 0 0 CIX 
Table 8. Common agricultural pesticides utilized in Dade County, Florida (1980-1981). 

Dade County Acreage 

Crop (1978-79) Commonly used pesticides 

Tomatoes 

Beans 

Potatoes 

Squash 

Sweet Corn 

Avocados 

Field Corn 

Variable 

Maneb 

Mancozeb 

Copper 

Sulfur 

Maneb 

Mancozeb 

Mancozeb 

Phorate 

Ethylene Dibromide 

Sulfur 

Methomyl 

Acephate 

Parathion 

Mancozeb 

Methomyl 

Dicofol 

Malathion 

Mancozeb 

Atrazine 

Methomyl 

Paraquat 

Zineb 

Glyphosate 

Methomyl 

Methyl Bromide 

Methamidophos 

~ethom~l 

Trif luralin 

Dimethoate 

Methimidophos 

Car bar yl 

Maneb 

Mancozeb 

Copper 

Benomyl 

Ethion 

Maneb 

Chlorpyrifos 

Aldicarb 

Simazine 

Car bophenothion 

Note: The above list has been assembled from several sources including the Florida Department 

Regulation, Dade County Cooperative Extension Service, Institute of Food and Agr

(University of Florida), and various growers and supply houses in Dade County. 
concentrations and pH value mesurements at the USGS station fell within a 

relatively narrow range, and were typical of the generally well buffered freshwaters of the region. 

Nutrient data indicates that a high nitrogen loading exists in the area of C-103N, 

as the highest nitrite plus nitrate nitrogen concentrations occurring in the Dade 

County canal system are reported here. Total phosphorus concentrations at the 

USGS station were found to be very low throughout the period of record. 

Bacteriological counts at the four DERM stations indicate that in general bacteriological contamination in the Mowry Canal system is not a problem, and counts were 

typically the lowest reported in Dade County canals. 

A number of heavy metals and pesticides have been detected in the sediments at 

the USGS station. However, a paucity of data prevents a definitive understanding 

of the situation at this time. 

ACKNOWLEDGEMENTS 

The authors would like to express their appreciation to the following individuals 

and organizations for their assistance and cooperation in completing this report. 

Bob Brown of the South Florida Water Management District provided basin 

delineations for southeastern Dade County. Jim Labowski of the Dade County 

Department of Environmental Resources Management provided information and 

data from the DERM Canal Monitoring Program. Bob Usherson of the Dade County 

Planning Department was instrumental in providing the 1980 aerial land use 

photographs from which land use within the Mowry Canal basin was determined. 

Dr. David Parkhurst of Indiana University provided helpful insight into the 

statistical analysis. Finally, we would like to express our appreciation to 

Dr. John S. Zogorski of South Dakota School of Mines, Dr. Robert Hirsch and 

Dr. David Rickert both of the USGS (Water Resources Division, Reston, Virginia), 

and the Resources Management staff of Biscay,ne National Park who reviewed this 

manuscript, and Dee Childs and Jessie Brundige who typed the manuscript. 
LITERATURE CITED 

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Flora, M. D., and P. C. Rosendahl. 1981. Specific Conductance and Ionic 

Characteristics of the Shark River Slough, Everglades National Park, Florida. 

National Park Service, South Florida Research Center Report T-615, Homestead, FL. 55 p. 

Flora, M. D., and P. C. Rosendahl. 1982. An Analysis of Surface Water Nutrient 

Concentrations in the Shark River Slough, 1972-1980. National Park Service, 

South Florida Research Center Report T-653, Homestead, FL. 40 p. 

Juday, C., E. A. Birge, G. I. Kemmerer, and R. J. Robinson. 1927. Phosphorus 

Content of Lake Waters of Northeastern Wisconsin. Trans. Wis. Acad. Sci. 

Arts Lett., 23233-248. 

Labowski, J. 1982. Metropolitan Dade County Ground and Surface Water 

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Millar, P. S. 1981. Water quality analysis in the Water Conservation Areas, 1978 

and 1979. Technical Memorandum, South Florida Water Management 

District, West Palm Beach, FL. 63 p. 

National Oceanic and Atmospheric Administration. 1974-1981. Climatological 

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Orth, P. G. 1976. Nutrient Fluctuations in Groundwater Under an Agricultural 

Area, Dade County, Florida. Soil and Crop Science Society of Florida 

Proceedings, Vol. 35, p. 117- 121. 

Sokal, R. R., and F. J. Rohlf. 1969. Biometry. W. H. Freeman and Company, San 

Francisco, CA. 776 p. 

United States Environmental Protection Agency. 1976. Quality Criteria for 

Water. USEPA, Washington D.C. 256 p. ~-~ 

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United States Geological Survey. 1979. -Methods for Determination of Inorganic 

Substances in Water and Fluvial Sediments. Techniques of Water Resources 

Investigations of the United States Geological Survey. U. S. Government 

Printing Office, Washington, D. C. 626 p. 
Waite, T. D., and N. J. Freeman. 1977. Mathematics of Environmental Processes. 

Lexington Books, Lexington, MA. 170 p. 

Wetzel, R. G. 1975. Limnology. W. B. Sanders Co., Philadelphia, PA. 743 p. 

Zar, J. H. 1974. Biostatistical Analysis. Prentice-Hall, Inc., Englewood Cliffs, 

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