EPA 903/9--78-U08
ASSESS:iFN1 OF 19/7
'lA.lTP QUALITY CO'IDII IONS
IN THL UPPLR POTOMAC ESTUARY
July 197H
Leo J. Clark
and
Stephen f. Ruesch
-------
EPA 903/9-78-008
TABLE OF CONTENTS
Chapter Page
List of Figures ii
List of Tables iii
I. INTRODUCTION 1
II. DESCRIPTION OF MONITORING PROGRAM 5
III. FINDINGS AND CONCLUSIONS 13
A. General 13
B. Dissolved Oxygen 15
C. Algae 37
D. Nutrients 46
E. BOD 48
F. Estuary loadings 49
G. Herbicides 52
IV. FUTURE STUDY NEEDS 55
V. APPENDIX 56
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LIST OF FIGURES
Number Page
1 Secchi Disk vs. Chlorophyll a_ 14
2 DO Profile - September 8, 1977 16
3 Potomac Estuary DO Data: Rosier Bluff 23
Swan Creek (Drogue Study)
August 16, 1977
4 Potomac Estuary DO Data: Rosier Bluff 24
Piscataway Creek (Drogue Study)
August 30, 1977
5 Diurnal Transect Data: Potomac Estuary 26
at Hains Point - August 8-9, 1977
6 Diurnal DO Data - Hains Point 27
7 Diurnal Transect Data: Potomac Estuary 29
at Woodrow Wilson Bridge
August 9-10, 1977
8 Diurnal DO Data - Woodrow Wilson Bridge 30
9 Diurnal Transect Data: Potomac Estuary 32
at Fort Washington - August 10-11, 1977
10 Diurnal DO Data - Fort Washington 33
11 Chlorophyll a_, BOD, and DO Time Plots 39
12 Nitrogen - Chlorophyll Relationship 43
13 Phosphorus - Chlorophyll Relationship 44
A-l DO Isopleth: Potomac Estuary - 1977 56
A-2 Chlorophyll a_ Isopleth: Potomac Estuary 57
1977
A-3 NH3 Isopleth: Potomac Estuary - 1977 58
A-4 N02 + N03 Isopleth: Potomac Estuary - 1977 59
A-5 TP04 Isopleth: Potomac Estuary - 1977 60
A-6 Pi Isopleth: Potomac Estuary - 1977 61
A-7 BOD5 Isopleth: Potomac Estuary - 1977 62
ii
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LIST OF TABLES
Number Page
1 1977 Potomac Estuary Sampling Stations 6
2 Potomac Slack Water Runs 7
3 1977 Potomac Productivity Study 18
4 Analysis of Diurnal DO Variability - 20
August 16, 1977
5 Oxygen Production - Respiration Balance 21
6 Comparison of. Surface and Bottom DO - 28
Hains Point
7 Comparison of Surface and Bottom DO - 31
Woodrow Wilson Bridge
8 Comparison of Surface and Bottom DO - 34
Ft. Washington
9 Analysis of Diurnal DO Data 36
10 Relationship between Organic N&P and 41
Chlorophyll a_
11 Relationship between Inorganic N&P and 42
Chlorophyll a_
12 Summary of Sewage Treatment Plant 50
Effluent Data
A-l Summary of 1977 Potomac Estuary Data 63
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Chapter 1
INTRODUCTION
The water quality problems of the Potomac in the Wash-
ington area have been recognized since the days of President
Lincoln. Most of the difficulties at that time manifested them-
selves as sewage related odors which were abundant on warm summer
evenings. It was not until the 1930's that treatment facilities
were constructed to alleviate the obvious odor problems and less
obvious potential health hazards. Since that time, there has been
a continual race between .expanding population and construction of
treatment works in order to adequately treat the increased waste-
loads. Needless to say, treatment facilities still lag behind
current and anticipated needs in the Washington Metropolitan Area.
A major objective of the Water Quality Act and its
amendments is to "maintain the physical, chemical and biological
integrity of the Nation's waters". In the 1950's and 60's, changes
in growth of aquatic plants in the Potomac were documented. These
biological perturbations were indicative of more basic changes
taking place in the physical and chemical environment supporting
these aquatic plants. Such biological changes serve as barometers
pointing to ecological imbalance within the supporting environ-
ment, in this case the Potomac Estuary.
Extensive field studies in the Potomac Estuary were
conducted by EPA from 1966 to 1970. These studies pointed out -
the two major water quality problems existing during that period.
1
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These were an oxygen deficit brought about by discharge of organic
wastes and excessive eutrophication brought about by overenrich-
ment of the estuary with nutrients, particularly nitrogen and
phosphorus. These studies resulted in the publication of Technical
Report 35, which documented the scientific efforts carried out up
to that time by EPA's Annapolis Field Office (AFO).
Now, nearly a decade later, these problems are receiving
increased attention from regional planners, as attempts to find
a solution have grown more complex. The water quality problems
of the Potomac Estuary must be considered along with other local
environmental issues, such as: water supply needs incorporating
a low flow policy, pressure to rerate treatment capacity at Blue
Plains, land treatment alternatives, and other legitimate concerns.
that must somehow be orchestrated into an overall regional
management plan, which is at the same time rational, cost-effective,
and meets the needs of the public.
It is within this framework of competing uses of the
Potomac and conflicting needs of the public that EPA designed a
two-year water quality study to update the available data base
and provide current information on the status of the Potomac
Estuary. Our studies will not answer the many questions raised
by the various constituencies served by the Potomac, but they will
provide factual documentatipn on the river's health and an indica-
tion of the water quality trends evolving. Such information is
basic to the decision maker in formulating the available options
from which a workable decision can be made. It is this foundation
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of scientific reality that we are attempting to investigate and
document.
This report is intended to present the information
gained from the first half of the current two-year study effort.
The field phase was performed during the summer of 1977 and the
findings and conclusions herein evolved during the data interpreta-
tion and analysis phase that followed. Tabulations of the raw
data along with numerous graphs depicting this data are contained
throughout the text and in the Appendix. The ongoing usage of this
data within the context of mathematical modeling and for updating
portions of Technical Report 35 will be documented at a later time.
The specific objectives associated with this intensive
study of the Potomac Estuary's water quality are as follows:
Principal Objective
Provide the first phase of an updated technical data
base that will be necessary to address the denitrification deferral
issue at Blue Plains.
Secondary Objectives
1. Provide data for updating the verification and
improving the predictive reliability of AFO's
existing mathematical model of the Potomac
Estuary.
2. Determine the response of the Potomac Estuary
to the upgraded treatment currently in existence
at Blue Plains.
3. Provide a basis for establishing water quality
trends with particular emphasis on a comparison
3
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with data collected during the critical period
of 1965 - 1970.
4. Define current point source nutrient and oxygen
demanding loads entering the Potomac Estuary
along with those being contributed from the
Upper Basin.
5. Monitor the impact of a storm event in the WMA
on the widespread quality characteristics (as
opposed to high frequency monitoring for local-
ized effects) of the Estuary.
6. Determine the magnitude of selected herbicides
entering the Estuary from upstream and signifi-
cant point sources, and their extent in the
Estuary itself.
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Chapter II
DESCRIPTION OF MONITORING PROGRAM
This intensive monitoring program, conducted during
the period of July 18 to September 8, was comprised of three
distinct but interrelated phases: (Each of these phases will be
discussed below.)
A. Ambient Water Quality Monitoring
During six different weeks of the study period, two
boat runs, each following a slack water tide condition, were made
from the Route 301 Bridge (river mile 67.4) to Chain Bridge (river
mile 0.0). The stations sampled enroute, along with their river
miles and station number, are presented in Table 1. Because of
time constraints, these stations were sampled only within the
main channel and near the surface (i.e. no transect type data was
obtained). Shown in Table 2 are the approximate starting and
ending times for each run, and the significant rainfall events
that occurred during the study period. As can be seen, about an
equal number of low water and high water slack conditions were
sampled.
The following is a list of parameters that were analyzed
in conjunction with the ambient monitoring. All of these parameters
were measured routinely at every sampling location (with the
exception of herbicides, which were done only twice), as well as
ultimate (20 day) BOD and phytoplankton counts, which were done
on a selective basis.
5
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TABLE 1
1977 POTOMAC ESTUARY SAMPLING STATIONS
Station
Number
P-8
P-4
1
1-A
2
3
4
5
5-A
6
7
8
8-A
9
10
10-B
11
12
13
14
15
15-A
16
Name
Chain Bridge
Above Windy Run (opposite Georgetown
Reservoir
Key Bridge
Memorial Bridge
14th Street Bridge
Hains Point
Bellevue
Woodrow Wilson Bridge
Rosier Bluff
Opposite Broad Creek
Fort Washington (Piscataway)
Dogue Creek - Marshall Hall
Opposite Gunston Cove
Chapman Point - Hallowing Point
Indian Head
Deep Point - Freestone Point
Possum Point
Sandy Point
Smith Point
Maryland Point
Opposite Nanjemoy Creek
Mathias Point
Route 301 Bridge
RMI*
0
1.90
3.35
4.85
5.90
7.60
10.00
12.10
13.60
15.20
18.35
22.30
24.30
26.90
30.60
34.00
38.00
42.50
45.80
52.40
58.55
62.80
67.40
*Miles below Chain Bridge
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TABLE 2
POTOMAC SLACK WATER RUNS
JULY - SEPTEMBER, 1977
Date
7/17
7/18
7/20
7/21
7/25
7/27
8/01
8/03
8/05
8/14
8/22
8/24
8/29
8/30
8/31
9/06
9/08
Tide
LWS
LWS
HWS
LWS
LWS
HWS
HWS
HWS
*
HWS
HWS
LWS
Start
Time
1125
1245
1100
0855
1145
0830
1035
1130
1055
0910
1245
0930
End
Time
1700
1710
1505
1410
1610
1301
1540
1535
1512
1313
1700
1335
Remarks
Rain - .24"
Rain - .59"
Rain - .30"
Rain - 1.08"
Rain - .33"
Rain - 1.20"
Rain - 1.23". Fish kill
between Broad Creek and
Piscataway Creek
Rain - .40"
Fish kill between Broad
Creek and Piscataway
Creek
*Missed LWS
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Nitrogen Series
TKN
NHo
NOJ + N03
Phosphorus Series
Total P0d (filtered and unfiltered)
Inorganid PO, (filtered and unfiltered)
Carbon Series
Total C
Total Organic C
Biological
Chlorophyll a.
Phytoplankton Counts & Identification
Physical
Temperature
Turbidity
Secchi Disc
Other Chemicals
PH
BOD,
BOD°ultimate
DO
Salinity
Selected Herbicides
Atrazine
Simazine
B. STP Effluent Monitoring
A 24 hour composite effluent sample was obtained from
each of the major wastewater treatment plants (collected by plant
operators) in the WMA during the same days that the slack water
boat runs were being performed. These samples were preserved on
ice and returned to the AFO laboratory for analyses. The
8
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parameters that were analyzed included the nitrogen, phosphorus, and
carbon series (as contained in the aforementioned parameter list)
along with BOD5 and BODult on a once-per-week basis. In addition,
herbicide analyses were completed on one occasion. The following
is a list of the facilities that were sampled during this study:
Arlington Fairfax Co. - Pohick Creek
Alexandria Fairfax Co. - Dogue Creek
Blue Plains Fairfax Co. - Hunting Creek
Piscataway Fairfax Co. - Westgate Creek
At the time these STP samples were collected, AFO
personnel obtained a representative flow measurement in order that
mass loading rates could be computed.
C. Special Studies
Several special studies were incorporated in this monitor-
ing program to address the eutrophication state of the Potomac and
its relationship to the prevailing DO values that were being
measured. Much of the design and methodology employed in these
special studies was for the purpose of better defining various
model inputs, as required by its representation of the DO budget.
Practically all of these studies were performed before, in the
Potomac, with a high degree of success.
1. Algal Elemental Composition Analysis
Concentrated samples of the algal cells were collected
at different times, and at different locations in order to determine
the relative quantities of carbon, nitrogen, and phosphorus actually
contained within the cellular material. This information would
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have value in ascertaining the nutritional requirements of the algae,
and in interpreting whether or not a nutrient limited situation existed.
2. Bioassay Experiments
Dr. George Fitzgerald, University of Wisconsin, developed
several algal bioassay procedures for demonstrating whether the
environment has supplied limited or surplus quantities of nutrients.
These tests rely on in-situ algae but can be performed in a labora-
tory by measuring surplus phosphorus uptake, the enzyme alkaline
phosphatase, and the ammonia absorption potential under dark condi-
tions. The algal elemental composition analysis and Dr. Fitzgerald's
bioassay experiments are very complementary in assessing the impact
of nutrients on algal growth.
3. Light and Dark Bottle Studies
Both clear and opaque bottles were submerged at two
different depths (in and below the euphotic zone) and at several
different locations within the algal bloom for a period of 4-6
hours. The differences in the oxygen content of the bottles
can be used to estimate the effects of algal photosynthesis and
respiration. If one knows the ambient chlorophyll concentrations,
these P and R rates can be expressed very conveniently on a per ug
chlorophyll basis.
4. Benthic Oxygen Demand Studies
AFO had previously designed and utilized a benthfc
respirometer that could be applied in estuarine environments, so long
as the water depths did not exceed 15-20 feet. This respirometer
was "planted" at several locations in the Potomac Estuary for
10
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at least one hour, and periodic DO readings within the
chamber were obtained. The magnitude of the DO variations as a
function of time constitutes an indication of the benthic oxygen
demand rate. One inherent assumption of this procedure is that
the benthic rate proceeds much quicker than the rate of bacterial
respiration within the water column.
5. Long Term BOD/Nitrification Rate Study
Since the characteristics of the treated wastewater
being discharged to the Potomac Estuary have changed significantly
during the past few years (particularly in the case of Blue Plains),
it was believed that previous estimates of both the carbonaceous
and nitrogenous oxidation rates may no longer be valid; therefore,
long term (i.e. 20 days) incubated bottle tests in the laboratory
were performed on a weekly basis using river samples, STP effluent
samples, and samples of the water entering the estuary at Chain
Bridge. An adequate number of DO measurements were obtained from
both inhibited and noninhibited samples to distinguish the individual
reaction rates and ultimate BOD values.
6. Diurnal Transect Sampling
Three stations were selected for cross-sectional (transect)
sampling at hourly intervals, for a total period of 24 hours. Data
of this nature is invaluable for assessing the impact of algae on
DO concentrations throughout the water column. However, since
this diurnal sampling was conducted at a fixed point, the tidal
effects had to be accounted for.
7. Drogue Studies
In order to obtain additional data related to a semi-
11
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diurnal DO cycle, but without having to consider the troublesome
tidal effects, two special studies were performed wherein a
floating drogue identifying a parcel of water was followed. Hourly
surface sampling was conducted while following the drogue with
samples being analyzed for DO and Chlorophyll.
It should be noted that separate reports, documenting
the special laboratory studies relating to algae and oxidation
rates, have been prepared and published by AFO.*
*Algal Nutrient Studies in the Potomac Estuary, Joseph Lee Slayton
& E. R. Trovato
Carbonaceous and Nitrogenous Demand Studies in the Potomac Estuary,
Joseph Lee Slayton & E. R. Trovato
12
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Chapter III
FINDINGS AND CONCLUSIONS
A. General
1. The 1977 Potomac Estuary Intensive Survey was conducted
during an extremely critical period (July 18 - September 8), as
evidenced by ambient flows and temperatures. River flows after
water supply withdrawals averaged about 1500 cfs, with the range
extending from 940 to 3600 cfs. Water temperatures averaged about
27.6°C. The maximum water temperatures (30-31°C) were as high as
any ever documented in the Estuary.
2. The water clarity of the Potomac Estuary was quite
low, as usual, particularly in the middle reach, which supports
the major algal blooms. Typical Secchi Disk readings were about
20-24 inches. Minimum values (during large algal blooms) ranged
between 7-12 inches, whereas the maximum readings in the extreme
upper reach (above Hains Point) ranged between 30-35 inches. (See
Figure 1.) Turbidity levels followed a similar pattern with respect
to water clarity.
3. An effort was made to identify rapid temporal changes
in the water quality of the Estuary based on the data collected
during slack water runs, and to relate changes to the occurrence
of storm events. No consistent pattern between these significant
changes (of which there were several for DO, BOD, and TPO^) and
preceeding climatological conditions could be discerned. Even
Secchi Disk and turbidity readings could not be closely associated
13
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Figure 1
SECCHI DISK VS. CHLOROPHYLL a
POTOMAC ESTUARY — PISCATAWAY CR. TO POSSUM PT.
(1977 DATA)
38 r
0 20 40 60 30 100 120 140 160 180 200 220 240 260 280
Chlorophyll a.— fig/1
14
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with particular storm events. This is not intended to imply that
storm water and/or combined sewer overflows do not adversely affect
the Estuary, but that these effects may be masked by the various
"in-stream" reactions and transport processes taking place, or
possibly, that the sampling did not occur at the most opportune
time.
4. Numerous regression/correlation analyses were per-
formed using data (see Table A-l) for each of the major para-
meters monitored during this study. Those which yielded statistically
significant results are shown below:
Y (dependent) X (independent) r
a) BOD5 TKN .73
b) Chloro BOD5 .58
c) Chloro TP04 .62
d) Chloro pH .66
e) Pi TP04 .76
f) NH3 TKN .68
g) N02 + N03 TKN .58
h) Secchi Disk Chloro .54
i) BOD5 TP04 .55
j) Secchi Disk Turbidity .51
B. Dissolved Oxygen
1. Minimum DO concentrations measured during the twelve
slack water runs varied between 2-3 mg/1. (See Figure A-1.) These
low DO levels normally occurred in the immediate vicinity of the Blue
Plains STP. The most critical DO profile was observed on September 8.
(See Figure 2) -,,-
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Figure 2
DO PROFILE
POTOMAC ESTUARY
SEPT. 8, 1977
5 -
4 -
3 -
1 -
Temp = 27°C
Flow = 1100 cfs
10
20 30 40
Miles Below Chain Br.
50
60
70
16
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2. Based upon a statistical analysis of intensive type
data collected in the Potomac Estuary during 1965, 1968, 1969,
and 1970, as well as the 1977 data, it can be concluded that DO
concentrations in the critical reach downstream of Blue Plains
have, in fact, improved with time. While difficult to quantitate
because of data anomalies and limitations, it appears that on the
average, DO levels have increased by about 1.0-2.0 mg/1. All of
this data was collected at surface stations having similar algal
bloom intensities, and was taken during low flow and high tempera-
ture conditions, making the data as comparable as possible.
3. A series of light and dark bottle DO analyses were
performed at depths of 1 foot and 6 feet between Broad Creek and
Indian Head. (See Table 3.) The purpose of this special study
was to estimate representative rates of algal photosynthesis and
respiration. Although a considerable amount of variability occurred,
the data was averaged and the following rates resulted:
P - 0.0140 mg 02/ug Chloro/hr
R - 0.0015*mg 02/ug Chloro/hr
*It was estimated that about 25% of this total respira-
tion rate was attributable to bacterial respiration, producing a
net algal respiration rate of 0.0011 mg 02/ug Chloro/hr.
These rates, it should be noted, compared quite well
with the original values presented in Technical Report 35 and used
in the Dynamic Estuary Model (P = 0.012 and R = 0.0008 mg 02/ug
Chloro/hr) along with a euphotic depth of 2.0 feet.
17
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1977 POTOMAC PRODUCTIVITY STUDY
Station
9 - Hallowing Point
IDA - Buoy 5
below Indian Hd.
7 - Piscatawav
8 - Doque Creek
00 8A - Gunston Cove
6 - Broad Creek
Initial
Chloro a_ DO
Date (yg/1) (mg/1)
8/08
8/08
8/10
8/11
8/11
8/16
31.5
169.5
69.0
52.5
165.0
61.5
10.59
16.27
5.00
6.61
11.66
2.98
(3 mg/1 02 demand * . 2/day rate *l/6 day
Total DO depletion = 0.4 mg/1
.'.Algal respiration = 75%, Bacterial respiration = 253
Assume further that of the total 0.0015 respiration, 0.0011 is actually
due to the algae with the remainder (0.0004) being of bacterial origin.
Depth
(ft)
surf
6
surf
6
1
1
6
6
1
1
6
6
1
1
6
6
1
1
6
6
Time
(hr)
4
4
4
4
4
6
4
6
6
4
6
4
6
4
6
4
3
6
3
6
DO
Light
ADO
Light - Initial
Dark
(mg/1 )
16.66
11.79
18.94
11.19
6.10
8.26
5.49
9.13
6.50
10.28
6.55
11.51
10.83
16.40
10.43
11.60
5.31
8.71
2.90
2.73
10.61
9.85
14.18
14.93
4.45
4.44
4.90
4.81
6.08
6.20
6.12
13.18
7.58
11.60
11.01
11.66
2.69
2.54
2.62
2.44
terial respiration
Initial - Dark P
(man)
6.07
(mg 02/y
0.0480
0.74
2.67 2.09 0.0040
1.34
1.10 0.55] 0.0040
3.26 0.56 P 0.0080
0.10 £
0.1 9j
0.53]
3.67 0.41 IP 0.0175
0.49IS
4.08
4.74 0.061P 0.0072
0.65J&
0
2.33 0.2
5.73 0.4
0.3
0.5
Use
9] 0.0126
4o 0.0155
6 '->
4
0.0140
R
gChloro/hr.) P/R
R-1
0 . 00580
0.00300 2:1
0.00200
0. 002001 § 4:1
0.00135)^
0.000361. 15:1
0. 00046 |§
'o
-Cs.
0.00168). 10:1
0.00195 §
0.00155]^;
— 1
Cu
0.00410 11:1 ^
0.00010 <*>
0.00065 oo
0
0. 00160] b 10:1
o.ooizols
0.00190 m
0.00150J
0.00150* 9.3:1 '
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4. The oxygen production rate observed on August 16
between 0600 hours and 1200 hours was +0.0020 mg 02/ug Chloro/hr.
(See item 7) The results of a light/dark bottle study performed
during this time period within the same reach of the Potomac
Estuary was used for comparison purposes. Assuming a water depth
of 15 feet and a euphotic zone of 2.0 feet, the P and R rates (0.014
and 0.0015 mg 02/ug Chloro/hr) translate to a net oxygen production
rate of +0.0004 mg 02/ug Chloro/hr. Assuming a water depth of
25 feet and a euphotic zone of 6.0 feet, the same P and R rates
translate to a net oxygen production rate of +0.0019 mg 02/ug
Chloro hr, which compares very favorably with the observed produc-
tion rate. (See Table 4)
5. An oxygen balance was developed utilizing the average
P and R rates obtained from the light and dark bottle studies. If
a euphotic zone of 2.0 feet is assumed, a zero net production of
oxygen is expected to occur when the water depth is about 13 feet.
Greater water depths will produce a net depletion of oxygen, whereas,
lesser water depths will produce a net addition of oxygen. The
actual quantities of oxygen added or consumed will, however, be
a function of the chlorophyll level. If a euphotic zone of 4.0
feet is assumed, and if it is further assumed that the same P rate
applies, there will be a net production of oxygen even when the
water depths are 25 feet. (See Table 5)
6. Seven measurements of the sediment oxygen demand
rate were made using a specially designed benthic respirometer.
The results are presented below:
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Table 4
ANALYSIS OF DIURNAL DO VARIABILITY
POTOMAC ESTUARY - AUGUST 16. 1977
(BROAD CREEK AREA)
Observed Increase in DO;
Time = 0600 - 1200 + .0020 mg°2/ug ch1oro/hr
Time = 1200 - 1700 + .0075 2/vg chloro/hr
Estimated Increase in DO Based on P&R Data:
Productivity Results (8/16/77)
P = 0.014 mg 02/wg chloro/hr
R = 0.0015 mg 0 chloro/hr
Assumptions #1 (used in Model)
Water Depth « 15 ft
Euphotic Zone = 2 ft
.014 * jf - .0015 = +.0004 mg °2/wg chloro/hr
Assumptions #2
Water Depth = 25 ft
Euphotic Zone = 6 ft
.014 * - -0015 = .0019 mg °2/Mg chloro/hr
20
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TABLE 5
OXYGEN PRODUCTION-RESPIRATION BALANCE
P =
Depth
(ft.)
5
10
15
20
25
5
10
15
20
25
5
10
15
20
25
POTOMAC
CHLORO A
0.014 MG 02/W9 CHLORO/HR.
ESTUARY
= 100 yg/1
R = 0.0011 MG
Increase in 02 Over Decrease in 02 Over
Water Column Due to Water Column Due to
Photosynthesis for Respiration for
12 Hours /Day 24 Hours /Day
Euphotic Zone
6.72
3.36
2.24
1.68
1.34
Euphotic Zone
10.08
5.04
3.36
2.52
2.02
Euphotic Zone
13.44
6.72
4.48
3.36
2.68
= 2.0'
2.64
2.64
2.64
2.64
2.64
= 3.0'
2.64
2.64
2.64
2.64
2.64
= 4.0'
2.64
2.64
2.64
2.64
2.64
02/vtq CHLORO/HR.
Net
(mq/1/day)
4.08
0.72
-0.40
-0.96
-1.30
7.44
2.40
0.72
-0.12
-0.62
10.80
4.08
1.84
0.72
0.04
21
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Station
Key Bridge -
VA Shore
Mains Point
Bellevue -
VA Side
% mile below Wood-
row Wilson Bridge
MD Side
Rosier Bluff -
MD Shore
Fort Washington -
Mid River
Dogue Creek -
MD Side
Rate
(gr/nr/day)
3.5
2.1
3.6
3.1
Remarks
1.4
1.5
5.3
Unrepresentative - main channel
of river (almost entire width)
contained a hard bottom.
Representative.
Soft, muddy bottom - probably
representative.
Soft bottom but unrepresentative
- bottom was hard along MD side
of shipping channel from Woodrow
Wilson Bridge to near Goose
Island.
Hard bottom with clay and
gravel - representative.
Soft bottom - representative.
Soft bottom - representative.
7. Two attempts were made to track and monitor a discrete
parcel of water in the Upper Potomac Estuary between Rosier Bluff
and Piscataway Creek over a semi-diurnal period extending from
0600 hours to about 1700 hours. A floating drogue was used for
this purpose. During both occasions (August 16 and 30), tidal
conditions, weather conditions, flows, and water temperatures were
very similar.
On August 16, the DO concentration (surface) was 1.5
mg/1 at 0600 hours and increased to about 5.5 mg/1 by 1700 hours.
(See Figure 3.) The ambient chlorophyll concentration was 80
ug/1. Computed net rates of oxygen production were 0.0020 mg 02/
ug Chloro/hr between 0600 and 1200 hours and 0.0075 mg 0£/ug Chloro/
hr between 1200 and 1700 hours.
22
-------
POTOMAC ESTUARY DO DATA
ROSIER BLUFF - SWAN CREEK (DROGUE STUDY)
AUGUST 16, 1977
Chloroji
Temp = 29 - 30°C
CO
t
Fog
&
Haze
Partly Sunny
&
Hazy
Mostly Sunny
&
Hot
Flooding Tide
co Ebbing Tide
A DO w 4 Mg/1
.0020 MgO2/pgChloro/Hr .0075 Mg O2/ji 9 Chloro/Hr
VQ
c
fD
'2 I 234 5 6 7 6 9 JO II 12 I 234567 8 9 10 II 12
NOON
HOURS
{ 1 f 1 f I I I
1 1 I
• 1 ' 1 ' ! 1
i i
-------
12
POTOMAC ESTUARY DO DATA
ROSIER BLUFF — PISCATAWAY CREEK (DROGUE STUDY)
AUGUST 30, 1977
Chloro_a zs 135jig/l
Temp = 28°C
Mostly
Cloudy
Sonny & Hot (Calm)
ro
-F*
10
Flooding Tide
Ebbing Tide
O>
A DO » 8 Mg/1
.0049 Mg O2/fl9 Chtoro/Hr
12 I 23456789
10 II 12 I
NOON
HOURS
234567 8 0 IO II 12
-------
On August 30, the DO concentration (surface) varied
from 3.0 mg/1 at 0600 hours, to 11 mg/1 at 1700 hours. (See
Figure 4.) This variation translated to a net oxygen production
rate of 0.0049 mg 02/ug Chloro/hr. The ambient chlorophyll con-
centration was 135 ug/1, and the weather was again mostly sunny
and hot.
8. Diurnal (24 hour) transect sampling was performed at
three stations during the week of August 8. These stations were
Mains Point, Woodrow Wilson Bridge, and Fort Washington. The
comments relating to the observed data at each station, followed
by a general conclusions statement, based upon a detailed interpre-
tation of this data, are given below:
a) Hains Point data (surface and transect mean) showed
a classical diurnal DO pattern. (See Figures 5 and 6 and Table 6.)
The total variability of the surface data was about 4.5 mg/1 (2.5
- 7.0 mg/1), whereas the transect mean data experienced a total
variability of about 3 mg/1 (3.5 - 6.5 mg/1). Variations at the
bottom were about the same as the surface, but not in phase. The
mean bottom DO was 3.9 mg/1. The average chlorophyll level was
65 ug/1.
b) Neither the mean transect data, nor the bottom
data collected at the Woodrow Wilson Bridge demonstrated a classical
diurnal DO pattern, although both showed substantial variability
(2-7 mg/1 and 1 - 4 mg/1, respectively). (See Figures 7 and 8
and Table 7.) The surface data, on the other hand, did demonstrate
such a pattern, with DO concentrations varying from about 8 mg/1
25
-------
Figure 5
DIURNAL TRANSECT DATA
POTOMAC ESTUARY @ HAINS PT.
AUGUST 8-9, 1977
I Transect
Rang*
, Transact
Mean
A Mid Channel, Surface
12 1 2 3 4 5 6 7 8 9 10 II 12 I 2 3 4 5 6 7 8 9 10 II 12
26
-------
r\>
§
Opposing Tidal *
Diurnal Effects
Daylight
DIURNAL DO DATA
HAINS PT.
Tidal & Diurnal
Effects in Hsrmony
Surfew
Bottom
Darkness
Daylight
6 7 8 9 10 11 12 T3 14 15 16 17 18 19 20 21 22 23 24 1 2 34
Flood | Ebb | Flood
6 7 8 9 10 11 12
I 'Ebb
o>
i i i r i r i • i » » ; i i »
! I
1 !
-------
Table 6
COMPARISON OF SURFACE AND BOTTOM DO
Date Time
8/08 1200
1300
1400
1500
1600
1700
1800
1900
2100
2200
2300
2400
8/09 0100
0200
0300
0400
0500
0600
0700
0800
0900
1000
1100
POTOMAC ESTUARY - 1977
MAINS POINT
Surface
Chloro DO
(ug/1) Tide (mg/1)
60 f 3.6
J, 3.7
80 I 5.1
LL.
4.0
60 7.2
][ 7.1
85 7.3
.a 6.4
70 £ 6.4
50 3.8
6.5
45 f. 5.1
4.5
80 •§ 4.1
o
C 4.0
65 2.9
2.7
80 | 2.7
3.8
75 .0 4.3
* 3.9
45 4.3
T 4.5
ADO* 4.5
Avg. 4.7
Bottom
DO Depth
(mg/1 ) (feet
2.5 30
4.8
2.0
1.9
1.5
1.9
2.8
4.6
6.5
6.0
6.8
5.6
5.1
4.0
3.4
3.0
3.0
2.9
3.6
3.8
3.8
4.9
4.6 v
4.5
3.9
28
-------
Figure 7
DIURNAL TRANSECT DATA
POTOMAC ESTUARY (3WOODROW WILSON BR.
AUGUST 9-10, 1977
DO
Trannet
Range
Trantect
A Mid Channel, Surface
ADO - 5 Mg/1
12 I 2 3 4 5 6 7 8 9 10 II 12 I 2 3 4 5 6 7 a 9 10 II 12
-------
i '
Figure 8
DIURNAL DO DATA
WOODROW WILSON BR.
Tidal & Diurnal Effects
in Harmony
Opposing Tidal &
Diurnal Effects
Surface
— — — Smooth Approximation
Bottom
Daylight
Darkness
Daylight
11 12 13 14 15 16 17 18 19 20 21 22 23 24 1 2 34 5 6 78 9 10 11 12
Flood I Ebb I Flood I Ebb
30
-------
Table 7
COMPARISON OF SURFACE AND BOTTOM DO
POTOMAC
ESTUARY - 1977
WOODROW WILSON BRIDGE
Date Time
8/09 1200
1300
1400
1500
1600
1700
1800
1900
2000
2100
2200
2300
2400
8/10 0100
0200
0300
0400
0500
0600
0700
0800
0900
1000
1100
Chloro
(ug/1 )
60
80
75
130
90
80
70
95
100
90
80
45
Surface
DO
Tide (mg/1)
t 4'7
1 5.5
1 6.9
^ 7.7
9.2
5.8
'* 6.8
8.3
6.7
5 6.0
5.5
4.9
5.0
3.8
o 3.0
o
EZ 1.7
2.0
2.4
Y 2.4
j
I t
2.5
1.8
&
uu 2.8
0.8
3.7
ADO* 6.0
Avg. 4.5
31
Bottom
DO Depth
(mg/1 ) (feet)
1.9 15
1.3
1.7
3.4
1.1
3.8
3.0
2.2
3.0
6.5
2.1
1.1
2.3
2.0
2.5
2.4
2.7
4.0
3.3
2.8
2.2
1.5
1.0
1.0
2.5
2.5
-------
Figure 9
DIURNAL TRANSECT DATA
POTOMAC ESTUARY (a) FORT WASHINGTON
AUGUST 10-11, 1977
13.0 1i4 1Z7
10
8
I ei
40 r-
20
I
1.2
1.0
.8
.6
S
T
O
R
M
Mid Channel. Surface
ADO = 4 M9/1
Chloro
TPO4
Flood !
I
Ebb
Flood
Ebb
.21 Z 3 4 3 «
8/10
8 9 10 II i2 I 2 3 4 5 6 7 S 9 10 !l 12
Houn 8/11
32
-------
Figure 10
DIURNAL DO DATA
FORT WASHINGTON
Tidal ft Diurnal Effects
in Harmony
Opposing Tidal &
Diurnal Effects
Surface
~a
i
Smooth Approximation
Bottom
Daylight
Darkness
Daylight
11 12 13 14 15 16 17 18 19 20 21 22 23 24 1 2 34 5 6 7 8 9 10 11 12
Flood | Ebb | Flood | Ebb
33
-------
Date
8/10
8/11
TABLE 8
COMPARISON OF SURFACE AND BOTTOM DO
POTOMAC ESTUARY
- 1977
FORT WASHINGTON
Time
1200
1300
1400
1500
1600
1700
1800
1900
2200
2300
2400
0100
0200
0300
0400
0500
0600
0700
0800
0900
1000
1100
Chloro
(ug/1)
60
45
60
70
60
55
45
60
50
45
40
Tide
t
§
ul
' r
1 1
.a
.a
Lul
> f
l \.
•a
§
n
>'
t ,
.a
.a
Ul
&
Surface
DO
(mg/1)
6.3
5.6
7.6
8.0
7.6
7.1
8.5
8.8
5.2
5.5
5.0
5.5
5.5
6.6
3.5
6.1
5.8
7.1
4.9
5.3
4.5
3.8
Bottom
DO Depth
(mg/1 ) (feet
2.4 45
3.2
3.2
3.1
4.1
5.8
3.8
4.2
2.9 30
3.5 45
3.6
3.8
3.9
3.3
4.2
4.8
5.2
5.0
4.5
4.1
3.8
4.3
BROAD CREEK
8/30
0600
120
3.1
4.0
20
ADO*
Avg.
34
4.0
6.0
2.0
4.0
-------
in late afternoon to about 2 mg/1 just before dawn. The mean sur-
face DO was 4.5 mg/1, and the mean bottom DO was 2.5 mg/1. The
average chlorophyll level was 80 ug/1.
c) In the case of Fort Washington, a classical
diurnal DO pattern could not be discerned in the transect mean
surface, or bottom data. (See Figures 9 and 10 and Table 8.)
The former exhibited a total variability ranging between 4-8 mg/1,
and the latter a range from 2.5-5 mg/1. The variability pattern
of both the surface and bottom data were quite similar. The mean
surface DO was 6.0 mg/1, and the mean bottom DO was 4.0 mg/1. The
average chlorophyll level was 55 ug/1.
It is important to recognize that two separate phenomena
are the major factors influencing the DO concentrations described
above: tidal action, and the algal photosynthesis/respiration cycle;
moreover, these processes, at certain times, will work in harmony
(i.e. be complementary), while at other times, they will be opposing.
An attempt was made to at least discern, if not quantitate, their
individual effects. (See Table 9.) Examination of longitudinal
DO gradients at the surface during slack water runs, and a comparison
of the observed DO variability at both surface and bottom waters (in
light of what was considered to be typical tidal variations), leads
to the conclusion that at the first two stations (1) algae produce
a large diurnal cycle in surface waters which exceeds the local
tidally influenced DO variations, and (2) this diurnal cycle is
undetectable in bottom waters where the tidal influence alone
accounts for practically all of the variability. It can be inferred
35
-------
TABLE 9
ANALYSIS OF DIURNAL DO DATA
POTOMAC ESTUARY
Station
Halns Point
Transect Mttn
Surface
Bottom
Woodrow Wilson Bridge
Surface
Bottom
Fort Washington
Surface
Bottom
Chloro
(ug/1)
65
65
65
80
80
55
55
ADO
(mg/1)
3.0
4.5
4.5
6.0
2.5
4.0
2.0
Rosier Bluff -
Swan Creek
Surface
Rosier Bluff -
Piscataway Creek
Surface
Summary
80
4.0
135 8.0
60-135 4-8
Remarks
Algal Influenced.
Algal Influenced.
Tidal Influenced.
Algal Influenced.
Tidal Influenced.
Algal influenced.
Random variation.
Algal influenced.
Algal influenced.
36
-------
that the vertical mixing time is of sufficient length to either
dampen out the diurnal cycle entirely, or to transmit it out of
phase with the surface at a decreased magnitude. At the third
station, it appears that tidal action constitutes the dominating
force, with respect to diurnal DO fluctuations.
C. Algae
1. Chlorophyll levels were highly variable, both over
time and space. Maximum concentrations of about 300 ug/1 were
recorded during one week in August between Gunston Cove and Indian
Head. Average values in the critical reach (between Dogue Creek
and Deep Point), were about 150 ug/1, and minimum values were less
than 100 ug/1. (See Figure A-2.)
2. Algal mats, floating on the surface of the Potomac
Estuary, were never observed during the course of this study, as
they were during the late 1960's; however, the greenish tint was
present in the high bloom areas extending from about the Woodrow
Wilson Bridge to Sandy Point. The indigenous forms of freshwater
algae this past summer appeared to be almost microscopic in size,
and well dispersed in the water column.
3. A bloom of marine algae, which imparted a "mahogany
tide" condition, was observed during the first week of the study
in the higher saline waters near the Route 301 Bridge. Chlorophyll
levels within the bloom peaked at about 400 ug/1.
4. Phytoplankton counts and species identification were
performed. During the early phase of the survey, when chlorophyll
levels were about 100 ug/1 or less, there appeared to be some
37
-------
diversity in algal populations, as both green and blue-green
varieties were observed; however, as the study progressed, and
chlorophyll levels attained their peak values, the blue-green algae
Oscillatoria became the dominant form, almost to the complete exclu-
sion of the other forms observed earlier. This behavior could
possibly be explained by the fact that Oscillatoria grow in long
strings, making it difficult for zooplankton to feed on them.
Assuming that other forms of algae are depleted due to continual
grazing by zooplankton, Oscillatoria would no longer have to compete
for the available nutrients. This would permit them to proliferate
greatly. Actual cell counts at this time were in the range of
70,000 to 90,000 per ml. Anacystis cyanea, the dominant form of
algae inhabiting the Potomac Estuary during the 1960's, was not
present to any noticeable degree.
5. An interesting situation, which warranted special atten-
tion, occurred between August 24, and September 8, when algal levels
declined drastically (as evidenced by a chlorophyll reduction of 200
ug/1). During this time period, data collected from Dogue Creek
to Deep Point showed that BOD5 concentrations increased 5-6 mg/1,
while DO concentrations decreased about 5 mg/1 (10 to 5 mg/1),
allowing for the fact that Blue Plains was exerting a greater than
usual influence upon DO on September 8,
(See Figure 11.) The effects of massive algal death and decomposition
on the DO budget may be quite significant, as indicated by this
data.
38
-------
Figure 11
I
Q
o
CO
i
o
Q
o3
Q
§
CHLORO a, BOD, & DO TIME PLOTS
POTOMAC ESTUARY - 1977
Dogue Creek - Hallowing Point *
10
9
8
7
6
5
4
3
2
1
0
10
9
8
7
6
5
4
3
2
1
A Chloro = 200 ptg/1
AB^O s 6 Mg/1
A D^ s *5 Mg/1
A Chloro = 200 jig/1 ^ *
AB$D 35 Mg/1 f
AD0 =*
i i i i i i i i i i
lit!
300
200
100
3
o
l»
I
10
300
200
100
O
I
I
1.
16182022242628301 3 5 791113151719212325272931246 810
July August Sept.
* Allowed about 1.0 Mg/1 D0 difference
due to high B.P. load on 9/6-8.
39
-------
6. Two separate and independent methods were used to esti-
mate a relationship among nitrogen and phosphorus utilization (in-
organic forms), algal content of carbon nitrogen and phosphorus
(organic forms), and chlorophyll a_. One method was based on an
analysis of the field data which emphasized spatial differences in
nutrient levels, while the other was based on an actual composition
analysis of the algal cells in the laboratory. The conclusions drawn
were as follows:
a) The mean ratio between organic nitrogen and chloro-
phyll indicated by the field data was 0.0028 mg N/ug Chloro, with a
standard deviation of 0.0008 mg N/ug Chloro. This ratio becomes
0.0056 mg N/ug Chloro if a 50% nitrogen recovery rate is assumed
for the analytical procedure followed in the laboratory. The mean
ratio between organic phosphorus and chlorophyll, also obtained from
field data, was 0.0019 mg PO^/ug Chloro, with a standard deviation
of 0.0004 mg P04/ug Chloro. (See Table 10 and Figures 12 and 13.)
b) Compositing selected inorganic nitrogen and phosphorus
field data as a function of chlorophyll, yielded typical ratios of
0.01 mg N/ug Chloro, and 0.0011 mg P04/ug Chloro, respectively.
(See Table 11 and Figures 12 and 13.)
c) Ten different laboratory analyses of the algal cells
for elemental composition provided a range of data as shown below:
OrgC: Chloro - 0.012 - 0.037 ®^—-
(average = 0.028 g
-------
TABLE 10
RELATIONSHIP BETWEEN
8/03
8/22
8'24
8/29
8/31
9/06
9/08
Station
7
8
10
8A
9
10
10B
11
6
7
8
5A
6
7
8
8A
9
10
10B
6
7
8
8A
9
10
10B
11
12
5A
6
7
8
8A
9
10
10B
11
12
13
6
7
8
8A
9
10
10B
11
8
8A
9
10
10B
11
12
13
14
10
10B
11
*Assume 50% "ecovery
ORGANIC N & P AND
CHLORO A
POTOMAC ESTUARY
Chloro
(mg/1)
147
132
104
no
123
118
129
120
112
104
124
104
130
169
172
276
306
264
284
198
139
147
261
306
303
312
228
168
118
122
129
152
180
190
261
300
294
200
158
111
111
134
176
188
172
195
171
148
104
146
180
130
180
186
146
254
188
100
130
120
Org *
N
.(39/.1 )
0.83
0.44
0.32
0.25
0.30
0.28
0.35
0.23
0.29
0.33
0.24
0.28
0.41
0.56
0.79
1.10
0.89
0.87
0.54
0.27
0.66
0.70
0.99
1.09
1.05
0.81
0.57
0.52
0.46
0.61
0.74
0.85
0.90
0.77
0.55
0.28
0.24
0.33
0.23
0.40
0.40
0.56
0.40
0.62
0.43
0.38
0.45
0.23
0.37
0.30
0.25
n T
Org
P04
(mg/1)
.18
.16
.23
.25
.28
.22
.25
.29
.21
.27
.29
.30
.29
.29
.30
.42
.46
.44
.42
.35
.30
.32
.39
.41
.50
.43
.35
.30
.19
.25
.23
.31
.30
.41
.49
.44
.50
--
.25
.21
.24
.32
.37
.37
.42
.40
.33
--.
.19
.22
.30
.20
.34
.33
.28
.30
--
.21
.28
.24
Max
Min
Mean
Std Dev
Ma N'
Mg Ch1<
.0056
.0033
.0029
.0020
.0025
.0022
.0029
.0021
.0028
.0027
.0023
.0022
.0024
.0033
.0029
.0036
.0034
.0031
.0027
.0019
.0045
.0027
.0032
.0036
.0034
.0036
.0034
.0044
----
.0030
.0034
.0039
.0033
.0030
.0026
.0028
.0018
.0022
.0030
.0017
.0023
.0021
.0033
.0021
.0036
.0029
.0026
.0025
.0018
.0021
.0016
.0010
—
.0056
.0010
.0028
.0008
.0012
.0012
.0022
.0023
.0023
.0019
.0019
.0024
.0019
.0026
.0023
.0029
.0022
.0017
.0017
.0015
.0015
.0017
.0015
.0018
.0022
.0022
.0015
.0013
.0017
.0014
.0015
.0018
.0016
.0020
.0018
.0020
.0017
.0022
.0019
.0015
.0017
.0016
.0019
.0022
.0024
.0020
.0020
.0024
.0021
.0019
.0018
.0015
.0017
.0015
.0019
.0018
.0019
.0012
.0021
.0022
.0020
.0029
.0012
.0019
.0004
-------
TABLE 11
RELATIONSHIP BETWEEN
INORGANIC
N & P AND CHLORO
A
POTOMAC ESTUARY
Date
7/20
7/27
8/01
8/03
8/22
8/24
8/29
8/31
9/06
Reach
(Stations)
6-11
5- 9
7-11
5- 8
5-8A
8A-11
5- 7
7-10B
6- 8
4- 6
5-10B
5-10B
4- 7
5A-10B
5A- 8
5-10B
3- 7
5-11
Chloro
(mg/1)
90
90
120
50
50
70
50
100
100
90
180
200
80
150
60
100
60
100
AN
(mg/D
.9
1.0
.8
.8
.5
1.0
1.0
1.8
1.9
1.6
1.7
1.7
AP
(mg/1)
.10
.04
.06
.06
.05
.06
.05
.08
42
-------
Figure 12
NITROGEN — CHLOROPHYLL RELATIONSHIP
POTOMAC ESTUARY — 1977
Field Data
OrgN
x Lab Data
O Field Data-Inorg N
H TR #35
-------
Figure 13
PHOSPHORUS — CHLOROPHYLL RELATIONSHIP
POTOMAC ESTUARY - 1977
• Field Data
OrgP
x Lab Data
O Field Data - Inorg P
O TR#35
100
Chloro a. —
200
280
44
-------
For the sake of comparison, the average values of
these ratios, which were contained in Technical Report 35 and were
based on laboratory findings, are given as follows:
0.045
0.010
mg ChToro
mg N
mg Chloro
mn DH
0.003
ug Chioro
m
d) The variability encountered in the 1977 phosphorus-
chlorophyll ratio data, depending upon whether the organic or
inorganic fraction is used, may be attributable to either analytical
inaccuracies or, possibly, some form of recycling process.
7. Algal bioassays that were developed by Dr. George
Fitzgerald, University of Wisconsin, were run on Potomac Estuary
samples. Phosphorus related bioassays (i.e. luxury PO* uptake ***
and alkaline phosphatase) indicated that this nutrient was not rate
<**
limiting algal growth, but rather, that a surplus might have existed.
The data obtained from the nitrogen related bioassay (i.e. ammonium „„
uptake rates in the dark) was somewhat inconclusive, but did indi-
cate that inorganic nitrogen was approaching a limiting situation
during the latter phase of the study.
8. A laboratory experiment (acetylene reduction) was
performed near the end of the survey to determine if the blue-green m
algae in the Potomac were fixing atmospheric nitrogen (this was a
definite possibility, since inorganic nitrogen concentrations in the"*
water column were almost non-existent); the results of the test,
however, were negative.
45
-------
D. Nutrients
1. Maximum NH3 concentrations generally varied from about
1.0 to 1.5 mg/1, and invariably occurred in the immediate vicinity
of Blue Plains. (See Figure A-3.) The dramatic decrease in NH3
to virtually undetectable levels, accompanied by a comparable increase
in N02 + N03 over a ten mile stretch of river, indicated that
nitrification was proceeding at a rapid rate because of the high
ambient temperatures.
2. The N02 + N03 nitrogen form peaked in the area of
maximum nitrification (below Blue Plains) at a level between 1.5 -
2.0 mg/1. (See Figure A-4.) Farther downstream, the concentrations
diminished greatly because of algal uptake or other biological
utilization.
3. As expected, significant quantities of both soluble and
particulate forms of organic nitrogen were present in the Upper
Potomac Estuary throughout the study period.
4. Several forms of phosphorus were measured, with the
most notable ones being total phosphorus, and filtered inorganic
(reactive) phosphorus. With the exception of the September 8 run,
TPO* concentrations were relatively constant in the estuary down-
stream of Blue Plains varying between 0.5 and 0.8 mg/1. (The
latter figure was obtained when a maximum algal bloom was present.)
(See Figure A-5.) The filtered Pi was more variable (0.1 - 0.3 mg/1)
on a spatial basis, but did not behave as expected. Instead of
diminishing to reflect its utilization by phytoplankton, concentra-
tions generally increased in a downstream direction regardless of
46
-------
ambient algal bloom conditions. (See Figure A-6.) Data collected
by the USGS during a similar time period confirmed this distribution
***ft
of reactive phosphorus in the Upper Potomac Estuary.
5. Maximum phosphorus concentrations, occurring in the
Upper Potomac Estuary near Blue Plains, showed a substantial decrease
(>50%) in 1977 over previous years, when levels ranging between """
1.5 to 3.0 mg/1 were experienced. Inorganic nitrogen, on the other
hand, did not exhibit a well defined trend in either direction
within this same reach.
P*t»
6. Concentrations of total inorganic carbon generally
varied from about 20-30 mg/1, with no particular spatial or temporal •*
pattern evident. Even when maximum algal levels were encountered, ""
inorganic carbon levels persisted above 20 mg/1, leading one to
believe that this nutrient is extremely abundant in the Potomac
Estuary and does not have growth rate limiting consequences.
7. An analysis of the spatial distribution of nutrients """
and chlorophyll (i.e. phytoplankton densities) in the Potomac
Estuary,, indicates that the inorganic nitrogen may be limiting algal
Sta
growth in the area of maximum production (downstream of Hallowing
Point), since concentrations of both NH3 amd N03 become non-detectabl*>
as bloom conditions progress. It is suspected that light may be —
the limiting factor in the upper zone (i.e. upstream of Piscataway *"*
Creek), where considerably lower chlorophyll levels are normally
found.
mm
8. There is no indication, based on the observed water
quality monitoring data, that phosphorus is a rate limiting nutrient **
B.I)
47
-------
at the present time. The fact that inorganic (soluble) phosphorus
concentrations actually experienced an increase in areas of algal
bloom production indicates that recycling/regeneration or possible
recruitment from the benthos may be important reactions which should
be further investigated.
E. BOD
1. Maximum BODg concentrations in the vicinity of Blue
Plains ranged from about 8-12 mg/1. A BQD5 of 10 mg/1 was also
measured in the area of a peak algae bloom on August 29. (See
Figure A-7.)
2. Long term (e.g. 20 days) inhibited and non-inhibited
BOD analyses were performed on many of the river samples in order to
approximate the first order decay or oxidation rates for both the
carbonaceous and nitrogenous components. The mean rates provided
by this study are as follows:
CBOD - 0.14/day (base e - 20°C) (Std. Dev. = 0.023)
NBOD - 0.14/day (base e - 20°C) (Std. Dev. = 0.053)
3. The CBOD rates were also estimated for the major load
inputs to the estuary. The average value for the wastewater
effluents was 0.17/day (base e - 20°C), and that for the Chain
Bridge station was 0.13/day (base e - 20°C). The standard devia-
tions were 0.046 and 0.026, respectively.
4. A sizeable percentage of the BOD5 measurement for the
wastewater effluents was attributable to the nitrification reaction.
Consequently, the ratios of CBODult/BOD5, and CBODult/CBOD5 were
significantly different. The results of this special long term
48
-------
rate study indicated these ratios to be 1.30 and 1.75, respec-
tively.
F. Estuary Loadings
1. Blue Plains is by far the largest single point source
discharger of oxygen demanding material and nutrients in the Potomac
Estuary. (See Table 12) During the study period, it contributed
an average flow of 276 mgd, and the following average loadings:
% of Total Point Source
Parameter Average loading Hastewater Load
BOD5 58,000 Ibs/day* 78*
TKN 36,500 Ibs/day 75
NH3 32,500 Ibs/day 76
N02 + N03 250 Ibs/day 14
TP04 12,200 Ibs/day 55
2. For comparison, the average pollutant loadings from
Blue Plains in 1970, based on an average flow of 252 mgd, were
estimated to be as follows:
% of Total Point Source
Parameter Average Loading Wastewater Load
BOD5 104,000 Ibs/day 75
TKN 46,200 Ibs/day 85
N02 + N03 2,000 Ibs/day 55
TP04 52,000 Ibs/day 75
3. The non-tidal portion of the Potomac River continues
to be a significant contributor of BOD and certain nutrients to
the estuary. This is demonstrated by the relatively high average
*0n September 8, 1977, a mechanical breakdown occurred at the Blue
Plains treatment plant, causing a BODc loading of 344,000 Ibs/day.
If this loading were included in the analysis, the average BOD5 load
would be 82,000 Ibs/day,which constitutes 85% of the total point
source BODC load generated by the Washington Metropolitan Area.
o 4$
-------
TABLE 12
SUMMARY OF SEWAGE TREATMENT PLANT EFFLUENT DATA
Flow
(mgd)
TC
(mg/l
TOC
(mg/1)
TP
(mg/l)
Pi
(mg/l)
TKN
NO, + NO-,
BODr
(mg/t)
BODon
(mg/T]
Turbidity
Mean
M1n.
Max.
Mean
Min.
Max.
Mean
M1n.
Max.
Mean
M1n.
Max.
Mean
M1n.
Max.
Mean
Min.
Max.
Mean
Min.
Max.
Mean
Min.
Max.
Mean
Min.
flax.
Mean
Min.
Max.
Mean
Min.
Max.
1977 POTOMAC INTENSIVE
w
^k. *~ "*
§
19
O
•^
O-
11.91
7.50
16.00
43.97
29.15
87.03
12.66
6.72
28.37
2.98
1.96
5.00
2.36
1.72
4.07
6.00
4.01
12.90
4.73
1.74
6.77
4.53
2.33
12.90
6.57
0
17.40
o
Ol
c
<
19.56
17.80
21.00
69.63
63.83
85.48
18.82
9.11
42.44
15.20
12.18
17.02
13.56
11.96
15.20
14.88
7.39
21.60
4.26
1.57
9.29
13.59
6.90
21.60
8.79
1.20
15.60
ID
Q.
Ol
3
CO
276.40
251.00
313.00
83.50
73.20
131.37
33.62
19.11
96.37
5.30
4.11
8.00
3.74
2.99
6.00
15.88
14.47
17.89
.11
•ND
.68
14.09
11.60
16.70
34.28
3.20
132.00
T
c
3
01
S
19.39
18.77
20.18
105.34
70.56
141.53
52.02
11.15
103.31
19.71
17.00
23.22
16.52
13.00
19.26
20.28
17.94
21.90
.10
.ND
.26
18.55
15.60
20.60
49.30
9.30
70.30
Ol
IQ
S1
t/1
<1J
3
10.770
10.400
11.630
85.570
40.630
97.710
25.500
10.190
58.860
13.820
11.000
15.080
12.790
9.900
14.520
18.890
16.970
22.350
.025
ND
.050
16.000
5.600
19.800
12.700
2.900
19.200
01
Ol
f-
O)
c
+J
c
3
ac
4.09
3.75
4.48
32.50
27.91
39.70
12.97
6.65
17.23
.83
.48
1.09
.23
.12
.36
21.11
18.51
24.21
1.88
1.52
2.28
19.69
17.10
23.10
13.10
2.80
18.30
01
01
s-
01
3
§>
0
2.26
2.09
2.63
30.65
24.28
37.98
14.41
9.37
19.55
.89
.72
1.45
.19
.09
.34
21.78
16.08
34.42
1.50
.97
2.21
19.92
17.60
29.30
11.10
4.20
27.60
Ol
Ol
t.
"
o
•1—
o
D.
14.02
13.46
14.75
85.35
58.40
101.49
28.00
11.33
55.89
22.35
20.20
23.52
19.64
18.40
21.56
21.81
10.61
.30.53
1.87
.07
8.24
19.18
6.02
24.20
15.78
3.00
23.70
4.13
2.50
6.50
6.27
2.50
10.00
15.54
8.00
25.50
25.10
20.00
30.00
7.800
4.750
12.000
6.98
4.00
15.00
9.55
5.50
19.00
8.93
4.00
12.00
50
-------
concentrations of these pollutants measured at the Chain Bridge
station during the study period, as shown in the table below:
Parameter
BOD5
DO
TKN
Org.-N
NH3
N02 + N03
TP04
Inorg. P04
Filt. Inorg. P04
TC
TOC
Chlorophyll a
4. Storm sewer and combined sewer contributions from the
WMA were estimated (order of magnitude type) based upon the best
available information. These loads, along with the two other major
loads to the Potomac Estuary (point source and upper basin inputs),
were translated to a total poundage for the study period and are
summarized and compared in the following table:
Average
Concentration
(igTT)
2.58
7.41
.49
.46
.03
.03
.25
.04
.02
32.28
5.43
42.88*
Standard
Deviation
(mg/1 )
.77
46
* ~W
.10
.10
.03
.04
.04
.05
0?
• \J£-
2.60
3.30
23.20*
Average
Loading
(Ibs/day)
2,358
444
415
29
25
230
40
28,533
4,693
41
51
-------
Parameter
Point Source
2.4 x 109
3.7 x 106
0.8 x 106
1.1 x 106
Upper Basin
6.5 x 109
1.0 x 106
0.1 x 106
0.1 x 106
Urban
2.2 x 109
2.0 x 106
0.3 x 106
0.5 x 106
Flow o
Volume (ft3)
BOD5 (Ibs)
Total N (Ibs)
Total P04 (Ibs)
5. On September 8, the last day of the survey, Blue
Plains was discharging a very poor quality effluent, as evidenced
by a BOD5 concentration of 132 mg/1 (344,160 Ibs/day, loading).
This BOD5 has since been refuted by Blue Plains personnel, but US6S
field staff sampling the Potomac has corroborated the fact that on
this date, the effluent from Blue Plains was very poor. Its impact
on the receiving water quality was considerable. The BOD concentra-
tions in the estuary near Blue Plains exceeded 11.0 mg/1 on September 8,
the highest value recorded during the survey. More importantly, the
DO concentrations on this date ranged between 1.8 and 4.0 mg/1 over
a 20 mile stretch of estuary from Bellevue to Indian Head. Other
water quality parameters, such as nutrients, were also elevated
during the September 8 run.
6. Herbicides
1. Special analyses for the herbicides atrazine and simazine
were performed on samples collected at approximately every other
station in the Potomac Estuary on July 18, and August 22. These
are widely used herbicides on corn crops, which have been identified
in other areas of the Chesapeake Bay.
52
-------
a) On July 18, a day following a rainfall event of 0.25
inches, maximum concentrations of both atrazine and simazine occurred
between the Woodrow Wilson Bridge and Dogue Creek. The levels
varied from .84 - 1.15 ug/1 and .49 - .78 ug/1, respectively. The
incoming concentrations at Chain Bridge were .46 ug/1 and .34 ug/1,
respectively.
b) On August 22, following an extended dry period,
atrazine and simazine concentrations were considerably lower in the
estuary: 0.4 - 0.5 ug/1, and 0.3 - 0.4 ug/1, respectively. Again,
maximum levels were recorded in the upper portion of the estuary near
and below Washington. Concentrations at Chain Bridge did not change
radically with atrazine being 0.38 ug/1 and simazine, 0.33 ug/1.
c) Atrazine and simazine were also monitored in the
effluents of the major sewage treatment plants and at Chain Bridge
on July 11. The results are shown in the table below:
Atrazine Simazine
Location (ug/1) (ug/1)
Piscataway STP .75 .38
Arlington STP 1.21 .54
Blue Plains STP 1.72 .55
Alexandria STP 1.08 .52
Westgate STP .26 .28
Hunting Creek STP .70 .10
Dogue Creek STP 1-06 .19
Pohick Creek STP 1.39 .52
Chain Bridge .92 .49
53
-------
The comparatively high values recorded at Chain
Bridge may have been due to a 0.43 inch rainfall which occurred on
July 9. The reason for the even higher values at most of the sewage
treatment plants has not been adequately determined.
54
-------
CHAPTER IV
FUTURE STUDY NEEDS
In addition to a continued ambient monitoring program in
the Potomac, forthcoming intensive studies to be conducted by AFO
will include the following elements to rectify present data gaps:
a) Expanded drogue studies to include 24
hour sampling at both surface and bottom.
b) Improved delineation of the BOD load
to include not only the carbonacenous
and nitrogenous components,but the
algal components as well.
c) Use of a photometer/transmissometer to
better define the euphotic zone in the
Upper Potomac Estuary.
d) Further SOD studies to extend the area
of coverage and to obtain a better
resolution of the data.
Another future study need concerns an improved definition
of the phosphorus budget and the role of suspended sediment as a
contributor of and a transport media for different forms of
phosphorus. Other reactions which should be considered and inves-
tigated in more detail as part of the phosphorus budget include
recycling and remineralization, both within the water column as
well as at the water sediment interface. This study, however, is
presently beyond the capabilities of AFO.
55
-------
APPENDIX
-------
Figure A-l
DO ISOPLETH (Mg/1)
POTOMAC ESTUARY - 1977
u
i
»
i
55
50
45
40
35
30
25
20
15
10
16182022242628301 357 9111315171921232527293124 6 8
July August Sept.
56
10
-------
Miles Below Chain Bridge
tn
s
o
x
o
o §
> i
o <
m l
II
I
to
c
-------
m
1
o
£
s
55
50
45
40
35
30
25
20
15
10
Figure A-3
NH3 ISOPLETH (Mg/1)
POTOMAC ESTUARY - 1977
16182022242628301 357 9111315171921232527293124 6 8 10
July August Sept.
58
-------
Miles Below Chain Bridge
S B
"
O O
m «•»
8
OD
-S
a>
-------
Figure A-5
ca
'<5
s
3
ca
i
55
50
45
40
35
30
25
20
15
10
TP*ISOPLETH(Mg/1)
POTOMAC ESTUARY - 1977
^-•6"
/
X
/
c
•^J
'V
i i i i i i i i i i i i i i i i i i i i
16182022242628301 357 9111315171921232527293124 6 8 10
July August Sept.
*AsPO
4
60
-------
Miles Below Chain Bridge
3 m
> D
O ^
m
X
-s
CD
I
cn
-------
Figure A-7
BOD ISOPLETH (Mg/1)
POTOMAC ESTUARY - 1977
00
e
3
s
ii
55
50
45
40
35
30
25
20
15
10
16 18 202224262830 1 3 5 7 911 13151719 21 2325 272931 2 4 6 8 10
July August Sept.
62
-------
SAMPLING STATION LOCATIONS
STATION LOCATION BUI (=MILFS RELOU CHAIN BRIDGE)
P-8 ........ CHAIN BRIDGE ................... 0-0
P-4 ........ WINDY RUN ...................... 1.9
1 ........ KFY BRIDGE ..................... 3.6
1-A ........ MEMORIAL PRIDGE ................ 4.°
2 ........ UTH ST. "5RIOGE ......... ..... .. 5.°
3 ........ MAINS POINT .................... 7.6
4 ........ BELLEVUE ....................... 10.0
s ........ UOODROW WILSON BRIDGE .......... 12.1
•5 -A ........ ROSIER BLUFF ................... 13.6
6 ........ BROAD CREFK ........... ........ 15.?
7 ........ FT. WASHINGTON ................. 18. £
* ........ DOGUE CREEK ........... ....... 22*3
9-A ........ GUNSTON COVE ................... 24 •"?
9 ........ CHAPMAN POINT .................. 26.9
10 ........ INDIAN HEAD ..... . ..it ...... t. .. 30.6
10-R ........ DEEP POINT ...... * ....... ....... 34.0
11 ........ POSSUM POINT ................... 38*0
12 ..... ... SANDY POINT .................... 62.5
13 ........ SMITH POINT .................... 45. f
14 ........ HARYLAND POINT ......... ....... 52.1 O
15 ........ NANJEWOY CREEK ................. 58.6 "^
15-A ........ HATHIAS POINT .................. 62." — ' .
16 ........ RT. 3H1 BRIDGE ................. 67.4 l£> f,
"
DATE FLOW AT LITTLE FALLS
JUL
JUL
JUL
JUL
AUG
AUG
AUG
AUG
rlUG
AUG
SEP
SFP
18
20
25
27
1
^
22
24
29
31
6
8
• ••«•**<•*«« 17 80
«««« IftOICATFS A LA« ACCIDENT OR TEST NOT DOME
0.0 INDICATES THF PARAMETER WAS NON-DETECTABLE
O
m
QJ
c-f
fu
1 f i
-------
f i
HOTOMAC RIVER DATA FOR JULY ia» 1977
STATION
l> _O
r ~
r-4
1
1-A
2
3
4
5
(Ti 5-A
6
7
8
8-A
9
10
10-B
11
12
1?
14
15
1«-«
16
TFMP
(C )
30.6
30.6
30.7
30.7
30.7
3n.a
sn.s
30.6
30.6
30.1
30.1
30.2
30.4
3H.O
30.0
30.2
29.0
30.3
29.2
29.6
28.9
28.7
SAL IN1TY
(P PT)
On
• U
P.O
n.o
P.O
n.o
n.o
P.O
n.o
n.o
n.o
n.o
0.0
n.o
0.0
0.0
n.o
0.0
n.7
1.0
*.9
r.4
6.8
7e5
PH
MMMM
MMMM
MMMM
MMMM
MMMM
MMMM
MMMM
MMMM
MMMM
MMMM
MMMM
MMMM
MMMM
MMMM
MMMM
MMMM
M MM N
MKMM
MMMM
MMMM
MMMM
MMMM
SECCHI
(IN)
23.0
74.0
24.0
76.0
18.0
23.0
77.0
70.0
74.0
20.0
20.0
20,0
73.0
72.0
71.0
24.0
13.0
K.O
13.0
73,0
27,0
30.0
TURBIDITY
9 • 20
8. SO
8. no
7.50
6.80
15.00
8.20
8.50
8.50
6.10
10.20
6.20
8.00
8.80
8.50
10.20
10.40
?0.00
10.80
75.10
18.00
19. On
15.OO
TKN
(MG/L>
0.50
0.55
0.51
0.48
0*42
0.71
1 .37
1 .37
1 .54
1.52
0.86
0.87
0.78
0.56
0.58
0.37
0.31
0.73
0.23
0.75
0.75
0.63
NH?
(MG/L)
One
• LIT
0.0
o.n
0.0
0.0
0.78
0.71
1.37
1.37
1.54
0.29
0.07
0.03
0.02
0.07
0.07
0.0*
0.06
O.n3
0.10
O.OS
0.08
0.03
N02+N03
(MG/L)
On
• U
0.0
0.0
0.0
0.0
0.18
0.38
1.24
1.7.4
0.83
1.26
1.77
1.M1
1.08
0.97
0.85
0.46
0.71
0.07
0.19
0.08
0.0
0.0
TP04
(MG/L)
n ^7
0.79
0.28
0.76
0.25
0.33
0.42
0.66
0.75
0.66
0.62
0.<4
0.50
0.50
0.46
0.43
0.41
0.57
0.51
0.49
0.4
1.11
()•*(,
PI
(MG/L)
On A
• U o
P.07
0.07
0.07
0.07
0.10
0.1 3
P. 27
0.37
0.32
0.25
0.1 9
0.18
D.17
0.17
0.18
0.15
1.26
0.2"
0.41
0.33
0.54
0.34
PICF)
I MG/L)
On
• U
0.0
n.o
n.o
0.0
o.o
0.0
0.15
0.22
0.20
0.14
0.11
0.09
0.08
n.09
0.09
n.06
0.12
0.14
0.24
0.65
n.40
1.23
\
TC
(MG/L)
'7.99
79.27
27.72
?7.63
'7.54
?7.54
30.55
30.09
79.95
30.18
30.64
31 .37
31. a'
31.64
31 .19
30.3?
79.64
78.13
74.62
7* .95
3* .75
76.67
TOC
(MG/L)
8*77
• f /
7.95
7.85
7.60
7.51
8.13
7.46
8.82
8.06
8.30
9.93
10.89
9.59
8.54
8.35
8.24
8.69
7.91
8.30
6.28
8.64
17.90
7.«1
CHLORO
(UG/L)
30.0
40.5
47.0
42.0
42.0
91 .5
114.0
99.0
90.0
147,0
132.0
102.0
99.0
79.5
7^,5
9n.o
85.5
88.5
25.5
60.0
40" .0
107,0
BOD 5
(HG/L)
f e ri
• J U
3.40
4.20
4.30
4 .60
5.10
4.00
6.20
7.90
6.50
5,80
5.60
4.90
5.00
4.80
4.10
".30
3.10
4.20
7.10
6.40
1^.70
A. 20
•)0
(MG/L)
6.7 X
• t J
7,37
6.97
6.71
8.22
8.79
7.01
7.02
4.59
4.13
5.21
7.22
7.01
S.75
7.32
7.^7
9.61
8.10
10.91
4.54
4.25
6.48
7.17
-------
POTOMAC RIVER OAT* FOR JULY 201 1977
S1A1 ION
1- -4
1
1-»
2
3
4
CM 5
cn
5-A
o
7
8
8-*
V
10
10-B
11
12
13
14
15
1*-ft
16
TEMP
(D
27.0
31.6
31 .9
31.9
31.5
31.6
31 .3
31 .5
31 .3
31.1
30.0
30.8
30.8
30.9
30.6
30.2
30.5
29.7
29.6
29.8
29.2
29,3
29.8
SALINITY PH
(PPT)
0.0 MMMM
0.0 MMMM
n.O MMMM
0.0 MMMM
0.0 MMMM
0.0 MMMM
0 .0 MMMM
n .0 MMMM
0.0 MMMM
0.0 MMMM
0.0 »«««
P.O »«««
0.0 MMMM
0.3 MMMM
0.4 «MMM
n ,4 MMMM
0.1 MMMM
2.2 »•••
4,9 «MMM
7.1 MMMM
7.7 MMMM
9.4 MMMM
(IN)
'6.0
?3.0
21.0
24.0
?6.0
26.0
26.0
23.0
23.0
23.0
24.0
27.0
'1.0
??.o
15.0
16.0
16.0
15,0
15,0
18,0
?H . J
?7.D
37,5
33.0
34,5
75.0
67.5
84.0
88.5
96.0
103.5
87.0
86,2
85.5
81 ,0
77.0
-------
i I
I I
POTOHAC RIVER DATA
STATION
»--4
1
1-A
2
3
4
5
5 -A
6
7
8
8 -A
9
10
1T1-6
11
12
1?
14
15
1-5 -A
16
TFHP SALINITY F-H
(C) (PPT)
33.0
27.7
27.8
27.6
27.4
26.5
26.8
26.7
26.8
26.6
27.2
26.9
26.9
27.0
27.0
26.9
26.8
26.7
26. 8
26.8
26.7
26.6
26.6
n.o
0.0
n.o
0.0
0.0
0.0
0.0
0.0
0.0
0.0
P.O
n.o
0.0
0.0
n.o
0.0
0.1
0.9
7.5
4.9
6.8
8.1
8.7
7*80
7.*0
7.80
7.70
....
7.10
7.10
7.10
7.20
7.30
7.90
8.20
8.40
8.40
8.00
7.70
8.00
7.30
7.10
7.10
7.20
7.20
SFCCHI
(IN)
31.0
33.0
79.0
'3.0
21.0
22.0
15.0
18.0
15.0
77.0
20.0
20.0
19.0
21.0
20.0
20.0
17.0
1H.O
74.0
77.0
75.0
30.0
TURBIOtTt
7.00
7.50
6.75
7.50
6.00
8.50
15.00
16.00
14.00
12.00
8.50
10.00
7.50
10.00
10.00
10.50
10.50
'0.00
70.00
10.10
9.50
10.00
7.50
TKN
(HG/L)
0.49
0.54
0.48
0.56
0.48
0.68
1.66
1 .62
1.15
1 .11
0*95
O.P5
0.91
0.72
0.60
0.57
0.47
0.47
0.32
0.*3
0.34
0.79
0.32
FUR JOLT 25 1977
NH3 N02+N03
(HG/L) (HG/L)
0.03
0.03
0.04
0.09
0.10
0.23
0.95
0.09
0.06
0.19
0.07
0.03
0.04
0.0
0.03
0.03
0.05
0.0
0.05
o.o*
0.08
0.0*
0.07
0.0
0.0
0.0
0.05
0.1?
0.54
0.04
1.28
1.53
1.65
1.5?
0.98
0.79
O.A7
0.60
0.67
0.35
0.15
0.19
0.12
0.09
0.05
0.0
TP04
(HC L)
0.26
0.24
0.18
0.24
0.2?
0. 40
0.79
0.35
0.81
0.67
0.44
0.54
0.51
0.58
0.51
0.49
0.53
0.58
0.44
0.40
0.40
0.38
0.38
PI
(HG/L)
0.0
0.0
0.0
0.0
0.0
0.10
0.34
0.35
0.28
0.24
0.17
0.16
0.16
0.18
1.17
0.20
0.28
0.29
0.34
0.30
0.27
0.29
0.28
PKF)
(HG/L)
0.0
0.0
0.0
0.0
0.0
0.04
0.15
0.18
0.13
0.12
0.11
0.10
0.10
0.10
0*10
0.13
0.19
0.17
0.24
0.22
0.21
0.22
0.22
• «
Kll
TC TOC*
(HG/L) (HC/L)
78.59
30.05
29.85
79.46
30.9'
77.76
30.78
37.7'
30.68
30.48
30. 97
37.19
37.73
33.21
32.63
31.56
31.2'
'8.20
7* .10
76.5*
77.61
'6.60
"•.5°
1.12
4.10
6.01
6*14
5.13
4.13
5.52
9.68
6.16
7.02
6.50
7.09
7.78
9.21
7.47
4.82
5.48
8.19
7.63
9.52
11.98
13.59
11.64
CHLORO
(UC/L)
42.0
25.5
7.5
13.5
7.5
31.5
13.5
61.5
42.0
88.5
69.0
34.5
68.2
76.5
110,0
49.5
49.5
33.0
lfl.5
6.0
15.0
•»*.o
13.5
BODS
(HC/L)
1.90
"•.60
^•00
1.10
'.80
'.70
7.80
6.80
5.20
3.40
7.80
'.20
7.90
7.70
1.20
1 .00
1.10
1.20
0.30
0.90
1 .00
0.2U
no
(HG/L)
7.21
4.23
6.49
6.27
6.30
6.06
4.73
3.71
4.14
4.88
«.24
7.2tt
7.43
8.17
7.66
7.16
6.64
7.39
ft. 63
•=.58
5.43
5.05
5.10
-------
POTOMAC RIVER DATA FOR JULY 27» 1977
STAT.1UN
»-«
»•-«
1
1-»
2
3
4
5
5-«
6
7
8
8-A
9
10
10-B
11
12
13
14
15
15-A
16
TEMP
(C)
24.0
27.5
27.8
27.0
27.1
27.6
27.5
27.1
27.1
26.3
25.4
26.1
25.9
25.9
25.8
25.7
25*5
25.3
25.6
25.8
25.5
25.2
25.3
SAL TNITY
(PPT)
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
n.O
0.0
0*0
n.o
0*0
0.0
0.0
0.0
0.0
0.4
1.9
3.8
5*6
7.0
8.2
PH
KH »«
8.11
8.20
7.80
7.80
7.90
7.50
7.50
7.40
7.40
7.60
7.60
8.20
8.40
8.60
8.60
8*50
8*00
7.90
7.50
7.60
7.50
7.40
SFCCHI
(IN)
«..«
31.0
34.0
34.0
30.0
77.0
27.0
24.0
23.0
23.0
19.0
22.0
72.0
22.0
23.0
11.0
18.0
12.0
12.0
12*0
18.0
22.0
73.0
TURBIDITY
8.50
6.00
6.00
4.50
5.50
7.50
9.00
8.50
7.50
9.20
9.90
7*50
9.00
7.50
8.50
12.00
11.50
70.00
70.00
70.00
14.00
15.00
12.00
TKN
(HG/L)
0.46
0.35
0.38
0.37
0.40
0.58
0.99
1.21
1.28
1.30
0.90
0.82
0.73
0.78
O.*1
0.61
0.51
0.41
0.40
0.44
0.*5
0.32
0.32
NH?
(MG/L)
0.0
o.n
0.0
0.06
0.07
0.11
0.51
0.61
0.62
0.59
0.18
0.10
0.0
0.0
0.0
0*0
0.0
0.0
0.03
O.OS
0.10
0.11
0.12
N02+N03
(HG/L)
0.0
0.0
0.0
0.0
0*0
0.42
0.43
0.40
0.35
0.42
1*46
1.4*
1*09
0.97
0.7?
0.49
0.52
0.28
0.1*
0.19
0.15
0.10
0.05
TP04
(MC/L)
0.79
0.20
0.21
0.21
0.22
0.33
0.50
0.57
0.65
0.64
0.54
0^50
0.53
0.47
0.50
0.55
0.47
0*64
0.59
0.56
0.45
0.45
0.39
PI
(HG/L)
0*0
0*0
0*0
0*0
0.0
0.04
0.17
0*25
0*22
0.20
0*16
0*14
0*14
0.14
0*14
0*16
0*17
0*27
0.35
0*35
0.29
0.31
0.29
PI(F)
(HG/L)
0.0
0.0
n.o
0.0
0.0
0.0
0.08
0.13
0.12
0.11
0.09
0.09
0.09
0.09
0.09
0.11
0.13
0.17
0.24
0.26
0.24
0.24
0.24
TC
31.37
30.83
30.15
30.73
31.27
31.4?
33.22
32. 9*
33.13
32.59
32.34
34.89
31.47
33.27
3->*20
32.10
32.10
37.20
2H.53
27.63
21.68
28.19
29.07
TOC
(HG/L)
2.76
3.35
2.29
2.50
1.27
2.98
2.74
2.87
4.26
6.58
5.77
6.18
4.36
3.59
1.24
2.48
12.23
8*26
8.71
8.42
13.25
12.82
12.36
CHLORO
CUG/L)
52.5
36.0
3d.O
19.5
27.0
52.5
43.5
37.5
67.5
77.7
96*0
87.0
123.0
118.5
129.0
120.0
112.5
55.5
33.0
16.5
33.0
18.0
25.5
8005
(HG/L)
1.50
'.20
7.80
7.40
2.20
4.10
5.40
5.80
7.50
1.60
6.60
5.60
4.70
4.20
4.40
3.70
3.60
'•70
7.20
1.90
3.40
1.20
2.60
DO
(HG/L)
7.97
7.48
5.25
6.96
6.63
7.62
6.12
«=.52
5.86
5.19
6*12
5.71
8*36
8.18
8.53
S.73
8.37
7.67
7,51
•=•60
*.11
•=.42
4.95
1 1 1
-------
POTOMAC RIVFR DAT* FOR AUGUST 1, 1977
STATION
P-4
1
1-A
2
3
4
5
O1 5-»
00
6
7
8
8 -A
9
10
1TJ.-B
11
12
13
14
1"
1C
TEMP SALINITY PH SFCCHI
(C) (f-PT) (IN)
28.0
27.0
27.0
26.5
26.0
26.5
27.'0
28.0
27.5
27.5
27.0
27.5
• MM ft
27.0
27.5
26.2
27.2
26.2
27.5
27.3
26.6
26.4
0.0
0.0
0.0
0.0
0.0
0.0
n.o
0.0
0.0
n.o
n.o
P.O
n.o
0.0
0.0
n.o
0.0
1.1
1.8
4 .4
6.9
7.9
»»»> 35.Q
•»«» 35.0
»»»* -*o,o
»«•« 24.0
«««« 22.0
*»«» 22.0
«»M« 26.0
»»»« 28.0
««»« 21.0
»•«» 23.0
»«»« 23.0
«KK« 22.0
•«»» 23.0
«*»« 24.0
««»« 24.0
«»»« 15.0
»»«« 11. Q
««»» 20.0
»««« 20.0
«»•« 77.0
TURBIDITY
s.nn
5. on
5.00
7.50
6.50
15.00
15.00
8.50
7.50
6.90
10.50
8.00
7.50
9.7Q
7.50
6.50
10.00
17.00
20 .on
15.00
15.00
18.00
9.«;n
TKN
(MG/L)
0.41
0.36
0.34
0.33
0.42
0.72
1.06
1 .13
1.04
0.99
0.89
0.76
0.71
0*69
0.65
0.60
0.52
0.47
0.40
0.41
0.36
0.41
n mil.
NH3
(MG/L)
0.0
0.0
0.0
0.0
0.04
0.25
0.46
0.40
0.29
0.18
0.04
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.02
0.04
0.03
n-n/.
N02+N03
(HG/L)
Q.O
0.0
0.0
0.0
0.0
0.53
0.91
1.33
1.71
1.74
1.60
1 .25
0.9'
0.71
0.50
0.38
0.17
0.0
0.0
0.15
0.13
O.OB
n.nn
TP04 PI
(NG/L) (MG/L)
0.23
0.17
0.17
0.17
0.18
0.24
0.57
0.56
0.57
0.49
0.46
0.52
0.50
0.47
0.47
0.54
0.61
0.5H
0.51
0.43
0.4R
0.0
0.0
0.0
0.0
0.0
0.11
P. 19
0.25
0.21
0.18
0.16
0.15
0.16
0.16
0.16
0.16
0.20
0.24
0.32
0.34
0.30
0.31
n.?R
PI(F)
(MG/L)
0.0
0.0
0.0
n.o
0.0
0.04
0.09
n.15
0.14
0.11
0.09
0.09
0.11
0.10
0.11
0.12
n.14
0.16
0.23
0.26
0.23
0.24
n.pT
TC
(MG/L)
3^.86
'2.59
32.54
32.54
31 .17
30.35
32.64
37.59
33.35
32.03
31 .88
'3.71
32.85
31 .91
32.85
33. 20
31.52
21.91
71.22
77. 10
77,15
7S.37
TOC
(MG/L)
8.62
6.07
7.93
6.02
7.15
8.55
9.14
9.97
11.16
10.86
9.94
10.35
11.82
10.33
10.04
10.42
11.26
10.31
7.86
8. SO
7.94
7.39
CHLORO
(UG/L)
17.0
46.5
12.0
16.5
12.0
16.S
22.5
34.5
74.0
43.5
48.0
27.5
R7.0
60.0
66.0
76.5
S8.5
30.0
36.0
16.5
43.5
m .«;
B0t)5
(MG/L)
3.00
2.10
7.80
2.80
4.00
6.10
6.30
S.50
6.50
4.70
4.50
5.00
4.00
4.80
5.00
4.90
3.90
7.50
3.70
2.10
1.80
3.4n
DO
(MG/L)
7.38
7.35
8.77
7.99
6.77
5.37
5.47
4.54
4.43
• KM MB
4.05
7.76
3.20
8.62
10.34
11 .60
in.87
11.23
10.06
7.53
5.52
6.04
6.71
-------
f-OTOHAC 8JVPR DATA FOR AUGUST 3. 1977
cr>
OU:,UH
f-4
1
1-A
i
3
4
5
S-*
6
7
8
8-*
9
10
10-B
11
12
13
14
15
1"=-A
16
-FHf
27.0
28.0
27.9
27. Z
27.0
27.8
27. 0
27.0
27.0
27.0
27.2
27.2
27.2
27.0
24*8
26.4
26.7
26.5
26.8
26.7
26*8
26.6
26.5
SALINITY PH
(PPT)
n .0 « MM M
0.0 ««»«
o.o »«»»
o.o «««»
0.0 »»»»
0.0 tin ft •
0*0 «...
0*0 • »«»
0.0 • •»»
0.0 »»«»
n .0 « « » •
H.O »*«»
o.o «»««
n.o »«»»
0*6 a...
1.2 «»•«
7.1 *»•»
4.2 »«"•
6,4 ...»
8.1 ....
*.8 ....
0.9 »««ft
(IN)
?4.0
3?.0
3?.0
30.0
78.0
30.0
30.0
24.0
?4.0
15.0
20.0
26.0
?*.o
?0.0
16*0
11.0
12*0
12.0
H.O
18.0
19.0
M. .H
U'RBIDTI?
1 fl »f!fl
' U *' fU
7. no
5.90
6.00
6.00
9.00
6.00
s.'-^t)
3.00
7.62
9.50
6.50
8 .00
7,00
f .00
10.50
20.00
?0.20
25.00
19.11
10.00
10.00
10,?5
TKN NH3
0.44 0.09
0.&5 o.n?
0.^6 0.02
0.47 0.10
t)«53 0.12
U48 0.81
1 »26 0.47
i.3G a. 22
».<* 0.76
1.08 0.1?
D.tS 0.10
0.79 0.09
0.73 0.10
0.79 0.12
0.69 0*16
0*48 0*08
0*55 0.04
0.39 0.04
0.34 0*10
0.33 0.09
0*31 O.m
0*^3 0*12
0*31 0.13
"*CM*/L3
0. 7 A
• I A
0.06
0*0*
0.0
a.o
Q.*1
1.44
1.SO
1*64
1.6?
%13
0.^7
0.63
0.57
0.51
0.16
O.H7
0*04
0.17
0.1*
0.14
0.11
0.07
TP04
-MG/t)
0 y*
. c.
0.18
Q.1A
0.19
0.20
0.55
0*56
O.M
0.56
0.46
D.49
0.53
0.60
0.57
0.51
0.57
0.62
0*63
0*58
0.50
0.4?
0. M
0.34
PI
n-n A
• IS a
0.03
0.0?
0.03
0.03
0.20
0.22
0.20
0.19
0.15
0.15
0.16
0.20
0.17
0.16
P. 16
0.23
0.29
0.37
n.29
0.29
0.29
0.25
PI (F)
CHG/L'
On
• u
0.0
1.0
0.0
n.o
0.10
0.16
0.16
1.13
0.11
0.11
0.12
0.15
0.14
0.15
0.16
0.17
0.21
0. 28
0.23
0.24
0.25
0.21
TC
iHG/L)
•»4 c C
^ I . J J
30.30
30.01
31.40
31.25
31.80
31 .6"!
31.70
3?. 00
28.43
•".o^
32.85
32.40
31.75
33.70
^1.85
28.90
31.55
28.25
26.88
26.8?
26.61
2A.6*
TOC
(MS/1.)
4* e
*w J
2.95
^.20
3,70
2.55
3.35
4.35
5.60
5.75
3.88
6.05
6.90
6.30
S.75
6.20
4.40
3.40
6.60
4.10
4.58
3*40
3.20
'.20
CHLORU
-------
STATION
P-P
1—4
1
1-A
2
3
4
5
5 -A
6
7
8
8 -A
9
10
1TJ-B
11
12
13
14
15
T5-*
16
TEMP
(C)
25.0
26.2
26.2
26.2
26.0
26.1
25. 8
25.8
26.0
26.2
26.0
25.9
25.9
26.0
25.9
26.0
26.0
25.8
25.9
26.0
26.2
26.2
26.1
SAL iimr
CPPT)
0.0
n.o
0.0
n.o
n.o
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.4
1.2
2.4
4.2
6.6
8.5
ft.9
9.9
PH
8.80
8.70
8.40
8.00
7*60
7.30
7.30
7.50
7.80
8.00
8.00
9.10
9.10
9.00
8.70
8.30
8.00
7.60
7.50
7.40
7.30
7.50
POTOMAC RIVER DATA FOR AUCUST ??, 1977
SECCHI TURBIDITY TKN NH3 N02*N03 TP04 PI
(IN) (HG/L) (HC/L) (MC/L) (He/I) (HG/L)
71.0
23.0
73.0
23.0
17.0
18.0
20.0
20.0
14.0
13.0
11.0
12.0
12.0
11.0
18.0
15.0
13.0
13.0
24.0
74*0
2«i.O
26.0
19.00
6.00
8.50
8.50
15.00
19.00
70.00
8.50
19.00
18.25
20.00
22.00
25.00
75.00
75.50
70.00
25.00
30.00
26.00
19.00
18.00
15.00
19.00
0.62
0.62
0.65
0*55
0*63
1.75
1.61
1.33
1.10
1.06
1.19
1.17
1 .44
1.25
1.23
0*88
O.T?
0*53
0*44
0.36
0.^4
0.^6
0.37
0.0
0.0
0.0
0.0
0.07
0.51
0.79
0.37
0.03
0.07
0*0
0*0
0.0
0.0
0.0
0.0
0.0
0.0
0.0*
0*03
0.03
0.0?
0.03
0.0
0.0
0.0
0.0
0.05
0*69
1.52
1.85
1.81
1.«0
1.45
0*54
0*18
0.1*
0*09
0.0
0.0
0.13
0*32
0«T1
0*30
0.30
0.28
0.70
0.22
0.70
0.70
0.22
0.46
0.68
0.58
0.50
0.49
0.49
0.68
0.76
0.75
0*74
0.79
0.73
0.68
0*68
0.49
0.46
0.45
0.46
0*04
0.0
0*0
0*0
0.0
0.14
0.24
0.18
0.12
0.13
0.12
0.18
0*23
0*24
0.2*
0.37
0.41
0.43
0.47
0.37
0.36
0.35
n.34
PI(F)
(MC/L)
0.0
0.0
0*0
0.0
0.0
0.08
0*12
0.11
0.06
0.07
0.07
0.13
0.16
0.17
0.21
n.29
n.34
0.36
0.36
0.33
0.31
0.31
0.29
TC
(HG/L)
34.98
36.81
V5.52
•«8.34
34.64
34.54
M.04
34.29
32.12
34.44
33.60
34.91
36.17
35.92
37.55
35.92
35 .O*
33.11
79.01
77.68
?8.57
29.70
27.5*
TOC
(HC/L)
7.84
A. 61
3.69
5.68
1.98
6.12
10.26
7.00
5.48
9.03
7.50
9.72
11.55
10.95
11.89
9.72
9.23
7.26
2.96
1.78
1.63
S.13
2.71
CHLORU
(UC/L)
01.5
54.0
48.0
46.5
49.5
70.5
79.5
97.5
130.5
168.8
172.5
276*0
306.0
264*0
283.5
198.0
81.0
27.0
15.0
13.5
71.0
10.5
BODS
3*40
3.70
3*40
3*40
7*40
7.10
9.50
(1.30
6.60
5.60
5.10
5.30
5*40
5.00
5.50
^.70
3.20
1.80
1.00
9.50
0.80
1.40
1.00
DO
(HG/L)
7.78
10*19
0.93
0.14
7.61
6.34
3.73
5.04
6.93
6.96
8.02
10.07
9.61
10.19
8.99
8.34
7.26
7.16
5.91
5.25
4.98
5.i3
4.75
-------
POTOMAC RIVER DATA FOR AUGUST 7L,
STATION
P-8
P-4
1
1-A
2
3
4
5
5 -A
t>
7
8
8-A
9
10
TO -8
11
12
13
1i
15
15-A
16
TFMP
(C)
26.0
26.0
26.0
26.0
26.0
25.5
26.0
26.5
26.0
26.0
27.0
27.0
26.5
26.5
26*0
26.3
26.5
26.5
26.5
26.6
26.9
26.8
26.9
SAL INITY
(PPT)
n.o
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
1.0
1 .4
2.4
3.8
6.0
7.9
9.2
9.9
PH
7.60
7.40
7.80
7.60
7.20
7.10
7.00
7.00
7.10
• MKft
8.10
9.00
9.30
9.00
8.50
8*50
7.60
7.30
7.40
7.30
7.00
7.40
SFCCHI
CIN)
?2.0
31.0
31.0
13.0
13.0
18.0
12.0
1«.0
16.0
15,0
12.0
12.0
7.0
11.0
13.0
18.0
18.0
1R.O
20.0
32.0
?6.0
30.0
TURBJDITr TKN
(HG/L)
8.00
7.50
6.25
6.50
8.00
15.00
10.25
10*00
10.00
10.12
10*00
12.00
10.25
15.00
15.00
10.50
15.00
10. ?5
18*00
10.00
8.00
8.50
6.50
0.48
0.50
0.48
0.42
0.44
0.39
1.38
1*16
1.24
1 .09
1.1Z
1.10
1.27
1 .26
1.33
1.01
0*80
0.74
0*50
0.40
0*40
0.36
0.41
NH3
(H6/L)
0.02
0.06
0.03
0.02
0.05
0.3*
0.66
0.19
0.31
0.08
0.02
0.0
0.0
0.0
0.0
0.0
o.n
0.0
0.02
0.05
0.04
0.03
0.02
N02+N03
(H6/L)
0.06
0.0
0.0
0.0
0.0
0.77
1.20
1.9?
1.96
1.87
1.63
0.94
0.33
0.0
0.13
0.0
0.0
0*0
0.17
0.33
0.32
0.30
0.?9
TP04
(M6/L)
0.25
0.?2
0*18
0.15
0.1.8
0.4?
0.53
0.50
0.58
0.50
0*49
0.60
0.71
0.83
o.r?
0.74
0.71
0.66
0.60
0.52
0.47
0.43
0.51
1977
PI
(HG/L)
0.06
0.05
0.04
0.04
0.09
0.13
0.20
0.15
0.18
0.14
0.13
0.17
0.22
0.26
0*23
0.33
0.36
0.39
0.42
0.39
0.35
0.35
0.43
PI(F)
(MG/L)
0.0
0.0
0.0
n.o
0*0
0*08
0*14
0.10
0.11
0.09
0*08
0.12
0.14
0.17
0.16
0.26
0.31
0.31
0.35
0.33
0.32
0.30
0.38
TC
(NG/L)
31 .4*.
79.34
29.15
31.27
^4.51
37.40
33.38
31.97
32.44
3?. 26
31.97
32.26
33.2°
25.25
37.44
3^.57
33.76
32.21
2?*96
J7.4IS
?9.77
28.73
?7.6K
TOC
(MG/L)
4.08
2.76
3.16
2.21
3.47
4.73
5.41
8.26
9.68
10.84
6.72
7.71
8.93
3.42
8.38
7.23
7.82
5.63
2.82
2.71
2.98
2.20
1.16
CHLORO
-------
PUTOMAC RIVER PATA FOR AUGUST 29* .1977
ft«*ll (PPT) (IN) (MG/L) (HG/L) (HG/L) (HG/L) (WG/L) (MG/L) (MC/L) (MG/L) (U6/L) (MG/L) (HG/L)
I--8
P-4
1
1-A
2
3
4
5
5 -A
6
7
8
8-»
9
10
1TJ-B
11
12
13
14
n
15-A
16
27.0
28.0
29.0
27.0
27.0
28.0
28.0
29.0
28.0
28.0
27.0
27.0
27.0
27.0
27.0
27.2
26.8
26.3
27.1
26.3
26.4
26.0
26.3
0.0
n.o
0*0
0*0
0*0
0.0
n.o
n.o
0.0
0.0
0.0
n.o
0.0
0.0
0.0
0.5
1.1
2.2
3.4
5.5
7.7
8.6
0.3
«*»»
8 .on
8*30
8.30
7*60
7.60
7*40
7.30
7.30
7.40
7.40
7.90
8.60
8.90
9.20
9.20
9.10
7.80
7.90
«••«
7.30
7.10
7.40
****
23.0
24.0
23.0
13.0
14.0
15.0
19.0
22*0
21.0
13.0
14.0
10*0
12*0
1?*0
12.0
13.0
13.0
12*0
15.0
*«**
22.0
24.0
6.50
6.00
6.00
7.50
8.00
7.00
6*50
7.25
5.50
5.50
7.50
6.50
8.00
9.00
12.00
14.00
10.00
9.00
14*00
18.25
11 .00
6.00
5.00
0.47
0.45
0.49
0.48
0*51
1 .26
1.13
1.59
1 .24
1 .12
1 .18
1.19
1 .26
1**8
1 .33
1.11
0.89
0.63
0.57
0*39
0.38
0.35
0.33
0.0
0.0
0.0
0.0
0.04
0.62
0.52
0.68
0.33
0.29
0.02
0*0
0.0
0.0
0.0
0.0
0*0
0*0
0*0
0*0
0*0
o.n
0.0
0.0
0.0
0*0
0*0
0*11
0.65
D.A*
1.09
1.60
1.72
1.59
1.42
0.48
0.35
0.11
0.0
0.0
0.0
0*0
0.33
0.31
O.'O
O.'O
0.22
0.19
0*18
0.21
0.20
0*45
0.47
0.60
0.53
0.47
0.53
0.50
0.70
0.80
0.76
0.85
0.85
0.74
0*70
0.57
0.51
0.51
0.47
0*04
0.04
0.03
0.04
0.05
0.15
0.15
0.24
0.17
0.14
0.12
0.11
0.17
0.18
0.21
0.28
0.28
0.44
0*44
0.44
0.38
0.3R
0.38
0.01
0.01
0.01
0.01
0.01
0.08
0*09
0*10
0.11
0.08
0.06
0.06
n.13
0.12
0.14
0.21
0*31
0*36
0*37
0.37
0*33
0.33
0.35
32.42
33.33
?9.45
27.6*
27.6?
31.14
3?. 28
3'. 60
32.28
31.64
32.83
V.10
35.20
32.33
32.19
32.78
''.92
'2.05
32.37
27.7?
26.67
'6.90
27.90
2.27
3.63
0.0
2.14
2*28
3.32
5.05
5.72
5.05
4.54
5*06
5.02
7.82
6.88
7.69
7.24
6.58
4.43
5.34
2.55
2.45
0.0
0.0
34.5
28.5
24.0
40.5
37.5
93.0
90.0
90.0
121.5
129.0
151.5
180.0
190.5
261 .0
300.0
294.0
199.5
157.5
111.0
24.0
24.0
27.0
22*5
3*00
3.80
4.20
4.40
'.50
8*60
8.60
10*00
9.70
9.20
8.40
10.20
10.80
11.00
10.50
10.20
7.60
4.90
5.00
2.40
7.00
'.20
2.40
7,62
9.05
11.02
9.89
8,37
7.73
7.86
5.61
6.81
6*38
7.35
9.30
m.82
1Q.51
10.36
10.46
11.38
9.39
9.72
<.84
6.05
6.20
6.43
-------
POTOMAC RIVFR DATA FOR AUGUST 31. 1O77
STATION
P-8
P-4
1
1-»
2
3
4
5
5-A
6
7
8
8-A
9
10
TO -B
11
12
13
14
15
T5-A
16
TEMP
(0
23.0
29.1
29.3
28.3
27.3
28.7
28.8
28.8
28.3
29.0
28.1
27.7
28.0
28.0
27.8
27.7
26.9
27.5
26.8
26.8
27.0
27.1
27.9
SAL WTY PH
^2.13
31.74
30.39
30.19
29.51
32.01
^3.7?
33.24
32.81
30.66
32.66
33.10
33.00
32.90
33.19
32.81
32.2?
31 .5*
29.32
27.71
28. 5*
26.32
?7.10
3.47
3.69
2.95
^.41
4.05
•5.35
6.58
7.02
7.45
5.98
6.01
7.24
8.00
6.76
8.39
9.23
5.80
6.55
3.56
3.34
3.24
1.27
2.20
CHLORO
cue/D
19.5
30.0
21.0
33.0
25.5
66.0
75.0
114.0
91.5
111.0
133.5
176.3
187.5
172.5
195.0
171.0
14ft. 5
96.0
49.5
19.5
16.5
1-5.0
12.0
B005
(H6/L)
2.80
3.00
3.30
3.80
2.90
9.20
8.50
7.60
6.70
8.00
8.80
9.40
9.70
9.10
1.90
7.90
6.30
4.20
7.80
1.70
1.60
1.80
2.60
00
7.22
7.15
8.22
'.66
A.75
*.26
2.80
5.37
4.29
6.44
7.48
S.83
5.67
7.12
4*60
9.71
7.92
S.08
6.41
6.28
".93
6.28
5.84
-------
iTATIuN
,-8
1
1-*
2
3
4
5
5-*
6
7
8
8-*
9
10
VD-B
11
12
13
14
15
V5-*
16
TEMP
(C)
28.0
29.5
29.9
29.2
28.8
28.5
29.3
29.0
28.6
28.7
29.2
2ft. 7
28.7
28.6
28.8
28.8
28.8
29.0
28.9
28.4
2S.2
21.2
28.1
SALTNITY
-------
POTOMAC RIVER DATA FUR SEPTEMBER 8.1977
STATION
hg
~0
1—4
1
1-A
2
3
4
5
5-A
6
7
8
8-A
9
10
ro-d
11
12
13
14
15
15 -A
16
TEMP
(C)
•\~f n
2 I .0
27.0
i7.0
27.0
27.0
27.0
27.5
27.5
28.Q
27.5
27.5
27.4
27.4
27.3
27.3
26.9
27.0
27.1
26.9
27.1
26.5
26.3
26.8
SAL IHITY
(PPT)
n .0
0.0
n.o
0.0
0.0
0.0
0.0
0.0
n.o
0.0
0.0
0.2
0.2
0.3
0.4
1 .3
2.1
?.2
3.4
4.3
7.3
".8
10.0
PH
7.40
7.40
7.30
7.40
7.00
6.«5
6.90
6.90
6.90
6.90
7.25
7.00
7.20
7.20
7.60
7.65
7.7H
7.45
7.20
7.40
7.40
7.20
SECCHT
(IN)
24.0
24.0
25.0
24.0
19.0
25.0
31.0
34.0
?4.0
24.0
18.0
18.0
19.0
H.O
16.C
15.0
19.0
20.0
22.0
24.0
28.0
28.0
TURBIDITY
4 n nn
1 U»U(I
7.50
8*50
6.00
8.50
7.75
5.50
4.00
4.50
9.75
7.50
7.00
9.25
6.50
7.2";
6.50
7.00
10.00
9.00
15.10
B.2«
6.00
5.50
TKN
(HG/L)
Of A
• 46
0.43
0.41
0.40
0.27
1.05
1 .43
1.83
1.35
0.76
0.72
0.54
0.45
0.42
0.29
0.^4
0.39
0.*8
0.27
0.27
0.32
0.31
0.29
NH3
(HG/L)
On 7
• U r
0.11
0.13
0.17
0.13
0.59
1.43
1.8^
1.20
0.41
0.17
0.09
0.07
0.08
0.06
0.11
0.10
0.09
0.07
0.07
0.05
0.04
0.04
N02»N03
(HG/L)
Om
• Of
0.07
0.06
o.n
0.0
0.'1
0.98
1.22
1 .64
1.80
1.82
1.42
1.?0
1.07
0.83
0.30
o.m
0.09
0.10
0.22
0.21
0.1 a
0.70
Tf04
(H6/L)
aj*
. cl
0.21
0.21
0.20
0.20
0.47
0.92
1.17
0.71
0.49
0.38
0.43
0.47
0.47
0.56
0.6*
0.63
0.47
0.62
0.51
0.45
0.40
0.43
PI
(MG/L)
On C
.05
0.05
0.05
0.04
0.04
0.22
0.60
0.84
0*39
0.19
0*16
0.18
0.2^
0.23
0.28
0.33
0.33
0.39
0.40
0.39
0.33
0.31
0.34
(HG/L)
0.04
0.0
0.0
0.0
0*0
0.15
0.43
0.71
0.32
0.14
0.12
0.14
0.17
0.19
0.23
0.26
0.27
0.32
0.34
0.30
0.31
0.28
D.31
TC
(HG/L)
34 .40
31.89
31.93
31.31
32.18
30.39
3^.19
33.77
31.69
28.58
?9.91
30.72
30.97
30.43
31.06
31 .98
31.21
29.71
29.81
?6.61
2«>.32
77.5*
27.87
TOC
X(HG/L)
12. 29
12*00
5.85
10*46
11*33
9.97
12.58
10.93
11.32
16.24
12.30
12.38
11.42
10.88
11.51
1'.29
11.62
10.07
11.47
8.31
9.68
8.90
9.48
CHLORO
(UG/L)
45 .0
4?.0
37.5
40.5
49.5
58.5
69.0
55.5
58.5
75.0
67.5
72.0
85.5
79.5
100.5
130.5
120.0
82.5
17.0
22.5
2?. 5
19.5
27.0
eons
(Mfi/L)
?«00
2.60
2.70
1.80
2.40
5.30
9.40
11.80
11.20
6.60
4.60
4.70
5.00
4.60
4.90
4.90
*.60
3.10
3.40
1.60
1.80
1.20
1.70
no
(HG/L)
7.70
s.78
4.92
6.18
3.88
2.54
1.76
^.82
3.76
3.19
4.00
3,09
4.16
2.27
•=.18
A .63
6.37
6.51
5.46
6.42
6.40
4.92
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