U.S. ENVIRONMENTAL PROTECTION AGENCY
Annapolis Field Office
Annapolis Science Center
Annapolis, Maryland 21401
TECHNICAL REPORTS
Volume 1
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Table of Contents
Volume 1
A Technical Assessment of Current Water Quality
Conditions and Factors Affecting Water Quality
in the Upper Potomac Estuary
6 Sanitary Bacteriology of the Upper Potomac Estuary
7 The Potomac Estuary Mathematical Model
9 Nutrients in the Potomac River Basin
11 Optimal Release Sequences for Water Quality
Control in Multiple Reservoir Systems
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PUBLICATIONS
U.S. ENVIRONMENTAL PROTECTION AGENCY
REGION III
ANNAPOLIS FIELD OFFICE*
VOLUME 1
Technical Reports
5 A Technical Assessment of Current Water Quality
Conditions and Factors Affecting Water Quality in
the Upper Potomac Estuary
6 Sanitary Bacteriology of the Upper Potomac Estuary
7 The Potomac Estuary Mathematical Model
9 Nutrients in the Potomac River Basin
11 Optimal Release Sequences for Water Quality Control
in Multiple Reservoir Systems
VOLUME 2
Technical Reports
13 Mine Drainage in the North Branch Potomac River Basin
15 Nutrients in the Upper Potomac River Basin
17 Upper Potomac River Basin Water Quality Assessment
VOLUME 3
Technical Reports
19 Potomac-Piscataway Dye Release and Wastewater
Assimilation Studies
21 LNEPLT
23 XYPLOT
25 PLOT3D
* Formerly CB-SRBP, U.S. Department of Health, Education,
and Welfare; CFS-FWPCA, and CTSL-FUQA, Middle Atlantic
Region, U.S. Department of the Interior
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VOLUME 3 (continued)
Technical Reports
27 Water Quality and Wastewater Loadings - Upper Potomac
Estuary during 1969
VOLUME 4
Technical Reports
29 Step Backward Regression
31 Relative Contributions of Nutrients to the Potomac
River Basin from Various Sources
33 Mathematical Model Studies of Water Quality in the
Potomac Estuary
35 Water Resource - Water Supply Study of the Potomac
Estuary
VOLUME 5
Technical Reports
37 Nutrient Transport and Dissolved Oxygen Budget
Studies in the Potomac Estuary
39 Preliminary Analyses of the Wastewater and Assimilation
Capacities of the Anacostia Tidal River System
41 Current Water Quality Conditions and Investigations
in the Upper Potomac River Tidal System
43 Physical Data of the Potomac River Tidal System
Including Mathematical Model Segmentation
45 Nutrient Management in the Potomac Estuary
VOLUME 6
Technical Reports
47 Chesapeake Bay Nutrient Input Study
49 Heavy Metals Analyses of Bottom Sediment in the
Potomac River Estuary
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VOLUME 6 (continued)
Technical Reports
51 A System of Mathematical Models for Water Quality
Management
52 Numerical Method for Groundwater Hydraulics
53 Upper Potomac Estuary Eutrophication Control
Requirements
54 AUT0-QUAL Modelling System
Supplement AUT0-QUAL Modelling System: Modification for
to 54 Non-Point Source Loadings
VOLUME 7
Technical Reports
55 Water Quality Conditions in the Chesapeake Bay System
56 Nutrient Enrichment and Control Requirements in the
Upper Chesapeake Bay
57 The Potomac River Estuary in the Washington
Metropolitan Area - A History of its Water Quality
Problems and their Solution
VOLUME 8
Technical Reports
58 Application of AUT0-QUAL Modelling System to the
Patuxent River Basin
59 Distribution of Metals in Baltimore Harbor Sediments
60 Summary and Conclusions - Nutrient Transport and
Accountability in the Lower Susquehanna River Basin
VOLUME 9
Data Reports
Water Quality Survey, James River and Selected
Tributaries - October 1969
Water Quality Survey in the North Branch Potomac River
between Cumberland and Luke, Maryland - August 1967
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VOLUME 9 (continued)
Data Reports
Investigation of Water Quality in Chesapeake Bay and
Tributaries at Aberdeen Proving Ground, Department
of the Army, Aberdeen, Maryland - October-December 1967
Biological Survey of the Upper Potomac River and
Selected Tributaries - 1966-1968
Water Quality Survey of the Eastern Shore Chesapeake
Bay, Wicomico River, Pocomoke River, Nanticoke River,
Marshall Creek, Bunting Branch, and Chincoteague Bay -
Summer 1967
Head of Bay Study - Water Quality Survey of Northeast
River, Elk River, C & D Canal, Bohemia River, Sassafras
River and Upper Chesapeake Bay - Summer 1968 - Head ot
Bay Tributaries
Water Quality Survey of the Potomac Estuary - 1967
Water Quality Survey of the Potomac Estuary - 1968
Wastewater Treatment Plant Nutrient Survey - 1966-1967
Cooperative Bacteriological Study - Upper Chesapeake Bay
Dredging Spoil Disposal - Cruise Report No. 11
VOLUME 10
Data Reports
9 Water Quality Survey of the Potomac Estuary - 1965-1966
10 Water Quality Survey of the Annapolis Metro Area - 1967
11 Nutrient Data on Sediment Samples of the Potomac Estuary
1966-1968
12 1969 Head of the Bay Tributaries
13 Water Quality Survey of the Chesapeake Bay in the
Vicinity of Sandy Point - 1968
14 Water Quality Survey of the Chesapeake Bay in the
Vicinity of Sandy Point - 1969
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VOLUME 10(continued)
Data Reports
15 Water Quality Survey of the Patuxent River - 1967
16 Water Quality Survey of the Patuxent River - 1968
17 Water Quality Survey of the Patuxent River - 1969
18 Water Quality of the Potomac Estuary Transects,
Intensive and Southeast Water Laboratory Cooperative
Study - 1969
19 Water Quality Survey of the Potomac Estuary Phosphate
Tracer Study - 1969
VOLUME 11
Data Reports
20 Water Quality of the Potomac Estuary Transport Study
1969-1970
21 Water Quality Survey of the Piscataway Creek Watershed
1968-1970
22 Water Quality Survey of the Chesapeake Bay in the
Vicinity of Sandy Point - 1970
23 Water Quality Survey of the Head of the Chesapeake Bay
Maryland Tributaries - 1970-1971
24 Water Quality Survey of the Upper Chesapeake Bay
1969-1971
25 Water Quality of the Potomac Estuary Consolidated
Survey - 1970
26 Water Quality of the Potomac Estuary Dissolved Oxygen
Budget Studies - 1970
27 Potomac Estuary Wastewater Treatment Plants Survey
1970
28 Water Quality Survey of the Potomac Estuary Embayments
and Transects - 1970
29 Water Quality of the Upper Potomac Estuary Enforcement
Survey - 1970
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30
31
32
33
34
Appendix
to 1
Appendix
to 2
3
4
VOLUME 11 (continued)
Data Reports
Water Quality of the Potomac Estuary - Gilbert Swamp
and Allen's Fresh and Gunston Cove - 1970
Survey Results of the Chesapeake Bay Input Study -
1969-1970
Upper Chesapeake Bay Water Quality Studies - Bush River,
Spesutie Narrows and Swan Creek, C & D Canal, Chester
River, Severn River, Gunpowder, Middle and Bird Rivers -
1968-1971
Special Water Quality Surveys of the Potomac River Basin
Anacostia Estuary, Wicomico .River, St. Clement and
Breton Bays, Occoquan Bay - 1970-1971
Water Quality Survey of the Patuxent River - 1970
VOLUME 12
Working Documents
Biological Survey of the Susquehanna River and its
Tributaries between Danville, Pennsylvania and
Conowingo, Maryland
Tabulation of Bottom Organisms Observed at Sampling
Stations during the Biological Survey between Danville,
Pennsylvania and Conowingo, Maryland - November 1966
Biological Survey of the Susquehanna River and its
Tributaries between Cooperstown, New York and
Northumberland, Pennsylvnaia - January 1967
Tabulation of Bottom Organisms Observed at Sampling
Stations during the Biological Survey between Cooperstown,
New York and Northumberland, Pennsylvania - November 1966
VOLUME 13
Working Documents
Water Quality and Pollution Control Study, Mine Drainage
Chesapeake Bay-Delaware River Basins - July 1967
Biological Survey of Rock Creek (from Rockville, Maryland
to the Potomac River) October 1966
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VOLUME 13 (continued)
Working Documents
5 Summary of Water Quality and Waste Outfalls, Rock Creek
in Montgomery County, Maryland and the District of
Columbia - December 1966
6 Water Pollution Survey - Back River 1965 - February 1967
7 Efficiency Study of the District of Columbia Water
Pollution Control Plant - February 1967
VOLUME 14
Working Documents
8 Water Quality and Pollution Control Study - Susquehanna
River Basin from Northumberland to West Pittson
(Including the Lackawanna River Basin) March 1967
9 Water Quality and Pollution Control Study, Juniata
River Basin - March 1967
10 Water Quality and Pollution Control Study, Rappahannock
River Basin - March 1967
11 Water Quality and Pollution Control Study, Susquehanna
River Basin from Lake Otsego, New York, to Lake Lackawanna
River Confluence, Pennsylvania - April 1967
VOLUME 15
Working Documents
12 Water Quality and Pollution Control Study, York River
Basin - April 1967
13 Water Quality and Pollution Control Study, West Branch,
Susquehanna River Basin - April 1967
14 Water Quality and Pollution Control Study, James River
Basin - June 1967 ,
15 Water Quality and Pollution Control Study, Patuxent River
Basin - May 1967
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VOLUME 16
Working Documents
16 Water Quality and Pollution Control Study, Susquehanna
River Basin from Northumberland, Pennsylvania, to
Havre de Grace, Maryland - July 1967
17 Water Quality and Pollution Control Study, Potomac
River Basin - June 1967
18 Immediate Water Pollution Control Needs, Central Western
Shore of Chesapeake Bay Area (Magothy, Severn, South, and
West River Drainage Areas) July 1967
19 Immediate Water Pollution Control Needs, Northwest
Chesapaake Bay Area (Patapsco to Susquehanna Drainage
Basins in Maryland) August 1967
20 Immediate Water Pollution Control Needs - The Eastern
Shore of Delaware, Maryland and Virginia - September 1967
VOLUME 17
Working Documents
21 Biological Surveys of the Upper James River Basin
Covington, Clifton Forge, Big Island, Lynchburg, and
Piney River Areas - January 1968
22 Biological Survey of Antietam Creek and some of its
Tributaries from Waynesboro, Pennsylvania to Antietam,
Maryland - Potomac River Basin - February 1968
23 Biological Survey of the Monocacy River and Tributaries
from Gettysburg, Pennsylvania, to Maryland Rt. 28 Bridge
Potomac River Basin - January 1968
24 Water Quality Survey of Chesapeake Bay in the Vicinity of
Annapolis, Maryland - Summer 1967
25 Mine Drainage Pollution of the North Branch of Potomac
River - Interim Report - August 1968
26 Water Quality Survey in the Shenandoah River of the
Potomac River Basin - June 1967
27 Water Quality Survey in the James and Maury Rivers
Glasgow, Virginia - September 1967
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VOLUME 17 (continued)
Working Documents
28 Selected Biological Surveys in the James River Basin,
Gillie Creek in the Richmond Area, Appomattox River
in the Petersburg Area, Bailey Creek from Fort Lee
to Hopewell - April 1968
VOLUME 18
Working Documents
29 Biological Survey of the Upper and Middle Patuxent
River and some of its Tributaries - from Maryland
Route 97 Bridge near Roxbury Mills to the Maryland
Route 4 Bridge near Wayson's Corner, Maryland -
Chesapeake Drainage Basin - June 1968
30 Rock Creek Watershed - A Water Quality Study Report
March 1969
31 The Patuxent River - Water Quality Management -
Technical Evaluation - September 1969
VOLUME 19
Working Documents
Tabulation, Community and Source Facility Water Data
Maryland Portion, Chesapeake Drainage Area - October 1964
Waste Disposal Practices at Federal Installations
Patuxent River Basin - October 1964
Waste Disposal Practices at Federal Installations
Potomac River Basin below Washington, D.C.- November 1964
Waste Disposal Practices at Federal Installations
Chesapeake Bay Area of Maryland Excluding Potomac
and Patuxent River Basins - January 1965
The Potomac Estuary - Statistics and Projections -
February 1968
Patuxent River - Cross Sections and Mass Travel
Velocities - July 1968
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VOLUME 19 (continued)
Working Documents
Wastewater Inventory - Potomac River Basin -
December 1968
Wastewater Inventory - Upper Potomac River Basin -
October 1968
VOLUME 20
Technical Papers.
1 A Digital Technique for Calculating and Plotting
Dissolved Oxygen Deficits
2 A River-Mile Indexing System for Computer Application
in Storing and Retrieving Data (unavailable)
3 Oxygen Relationships in Streams, Methodology to be
Applied when Determining the Capacity of a Stream to
Assimilate Organic Wastes - October 1964
4 Estimating Diffusion Characteristics of Tidal Waters -
May 1965
5 Use of Rhodamine B Dye as a Tracer in Streams of the
Susquehanna River Basin - April 1965
6 An In-Situ Benthic Respirometer - December 1965
7 A Study of Tidal Dispersion in the Potomac River
February 1966
8 A Mathematical Model for the Potomac River - what it
has done and what it can do - December 1966
9 A Discussion and Tabulation of Diffusion Coefficients
for Tidal Waters Computed as a Function of Velocity
February 1967
10 Evaluation of Coliform Contribution by Pleasure Boats
July 1966
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VOLUME 21
Technical Papers
11 A Steady State Segmented Estuary Model
12 Simulation of Chloride Concentrations in the
Potomac Estuary - March 1968
13 Optimal Release Sequences for Water Quality
Control in Multiple-Reservoir Systems - 1968
VOLUME 22
Technical Papers
Summary Report - Pollution of Back River - January 1964
Summary of Water Quality - Potomac River Basin in
Maryland - October 1965
The Role of Mathematical Models in the Potomac River
Basin Water Quality Management Program - December 1967
Use of Mathematical Models as Aids to Decision Making
in Water Quality Control - February 1968
Piscataway Creek Watershed - A Water Quality Study
Report - August 1968
VOLUME 23
Ocean Dumping Surveys
Environmental Survey of an Interim Ocean Dumpsite,
Middle Atlantic Bight - September 1973
Environmental Survey of Two Interim Dumpsites,
Middle Atlantic Bight - January 1974
Environmental Survey of Two Interim Dumpsites
Middle Atlantic Bight - Supplemental Report -
October 1974
Effects of Ocean Disposal Activities on Mid-
continental Shelf Environment off Delaware
and Maryland - January 1975
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VOLUME 24
1976 Annual
Current Nutrient Assessment - Upper Potomac Estuary
Current Assessment Paper No. 1
Evaluation of Western Branch Wastewater Treatment
Plant Expansion - Phases I and II
Situation Report - Potomac River
Sediment Studies in Back River Estuary, Baltimore,
Maryland
Technical Distribution of Metals in Elizabeth River Sediments
Report 61
Technical A Water Quality Modelling Study of the Delaware
Report 62 Estuary
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A TECHNICAL ASSESSMENT
OF
CURRENT WATER QUALITY CONDITIONS
AND
FACTORS AFFECTING WATER QUALITY
IN THE
UPPER POTOMAC ESTUARY
March 1969
Norbert A. Jaworski
Donald W. Lear, Jr.
Johan A. Aalto
Technical Report No. 5
Chesapeake Technical Support Laboratory
Middle Atlantic Region
Federal Water Pollution Control Administration
U. S. Department of the Interior
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TABLE OF CONTENTS
fe&e
Li:*T OF TABLVT. iv
UM OF FlGUHh.' v
Chapter
I INTRODUCTION I- 1
JI CURRENT WATER QUALITY CONDITIOKS II - 1
A. ' fcal Coiiform Densities II - 1
B. Dissolved Oxygen (DO) II - 4
C. Iiocheraical Oxygen Demand (BOD) II - 6
1. Sources of BOD II - b
2. BOP Concentrations in the Estuary ... II - o
D. Nutrients - Phosphorus and Nitrogen .... 11-10
1. Sources of Nutrients 11-10
2. Nutrient Concentrations in the Estuary . 11-14
?,. Algal Standing Crop ...., II- 1','
III NUTRIENT-ALGAL RESPONSE AND ENVIRONMENTAL
REQUIREMENTS Ill - 1
A. Phosphorus Ill - 3
B. Nitrogen Ill - 5
C. Other Considerations Ill - 14
1. Stream Flow Ill - 14
2. Temperature, Solar Radiation and
Light Extinction Ill - U
3. Other Environaental Paraacters Ill - 15
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TABLE OF CONTENTS (Continued)
Chapter Page
FV ORGAN I r LOADINGS, IN TtfF UPPEP AND MIDDLE
ESTUARIES ......... ......... rv-
A. Al^al Car'Jonaceou* and Nitrogenous BOD ... IV - 1
>J. Vvastewater Carbonaceous BOD ........ IV - 4
V»astewater Nitrogenous BOD ...... . . . IV - 5
D. Beiahic-Background Carbonaceous and
Nitrogenovus BOD ............. IV - ^
E. Ultimate Oxygen Deaand Co.if>arison ..... IV - 6
F. Dissolved Oxygen Balance .......... IV - ''.'
CURRfJJT AND PROPOSED INVESTIGATIONS ...... V - 1
HEr KRENCES
iii
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LIST OF TABLES
Numoer Title Page
IT - 1 Wastf>water Loadings. Potomac Ketuary
Intensive r.urvey. Au#iiM \n-2?. V**& ..... II -
11-2 Summary o:' BOD and Nutrient Loadings, Upper
Potoaiac Estu«ry, August l°-22. 19b8 ..... II - H
II - 3 Average Total phosphorus Loading As PO^,
Potomac Piver Baain ............. 11-11
II - L, Average Total Nitrogen Loadings As N.
Potomac River Basin ......... .... 11-12
11 - 5 Predicted Average Montnly Nutrient Loadings,
Potomac River Near Washington, D.C ...... 11-13
', U - 1 Niitrient-Cnlorophyll Data rources ...... Ill - 2
. v
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LIST OF FIGURES
Number'- Title
t , '
1 - 1 Potomac *-.£tuarv
il - 1 >'f>M, '.-iLrr Ir.i low. Vkulrr Temperature, «na
. olar tediation, Upper Putomac Estuary,
May-October 1968 .............. II - 2
II - 2 i-'^al Coiifora Isopleth, Upper Potomac
;:siuary, May-October I°*o8 .......... II - 3
ii - ' Dissolved Oxygen Isopieth, Upper Potomac
"stuary, May-October 1968 .......... II - 5
il - ^ Ml Isopletn, Upper Potoraac Kstuary, May-
0?tx3oer 19^ ................ II - 9
II - 5 TKN is N Isopleth, Upper Potomac Estuary,
May-October 1968 .............. II - 15
NO^ as N Isopleth, Upper Potomac Estuary,
May-0c£ober 1968 .............. 11-16
II - '! Total P as PO^ Isopletn, Upper Potomac
Estuary, May-October 19t» .......... II - 1#
II - ,' "iii'-rophyll Isopleth, Upper Potomac Rstuary,
May-October 1968 .............. 11-19
111 - 1 Chlorophyll - Total Phosphorus Concentra-
tions, Summer Conditions, for Various Areas
of the Chesapeake Bay System ........ Ill - 4
III - 2 Chlorophyll - Inorganic Phosphorus Con-
centrations, Potomac Estuary, Intensive
Survey 196b ................ Ill - t>
III - 3 Nutrients and Chlorophyll, Potomac Estuary,
August 19-22, 1968 ............. Ill - 8
III - 4 Nutrient and Chlorophyll Loading Rates,
Potomac Fstuary, August 19-22, 1968 .... Ill - 9
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LIST OF FIGURES (Continued)
Nmnuer Title
111 - t> Chlorophyll - Inorganic Nitro^on Concen-
trations, ..vuaaer renditions, t'or Various
Areas of the Chesapeake Bay System .... Ill - 11
III - o Chloropnyll - Inorganic Nitrogen Concen-
trations, Potomac Estuary, Intensive
Surveys 19o6 and 1968 Ill - 12
IV - 1 five-DBy BOD Delineation and TOC-DO
Profiles, Potomc tetuary, Auguet 19-22,
196S IV - 2
IV - 2 A Schematic Diagram of Pissolved Oxygen
Interrelationships for the Three Major
biological Systens IV-8
vi
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1-1
CHAPTER I
INTRODUCTION
Watftr quality p>roblen*; Jn U>r Potomac River Has in, their sources
and corrective actions required, are the subject of continuing in-
vestigations oy the Chesapeake Technical Support Laboratory (CTSL)*
( ) the Middle Atlantic Region (MAR) of the Federal Water Pollution
/mtroJ Administration (FWPCA) in confonnance with provisions of
the Federal Water Pollution Control Act, as amended (3J U.S.C. 466
Hi seq.). A map of the Potomac Estuary is presented in Figure 1-1.
Initially, emphasis was placed on water quality monitoring and
the application and verification of mathematical models capable of
. iraulating the effects of low-flow augmentation, wastewater diversion,
water supply withdrawals and increased degrees of wastewater treat-
ment on dissolved oxygen (DO), phosphorus, and chloride concentra-
tions in the estuary. The use of raatneaatical model not only provides
predictive capability for effect of future wastewater discharges in
the upper Potomac Estuary but also furnishes a means of investi-
gating biological and environmental conditions affecting dissolved
oxygen.
Using the report "A Research Program for the Potomac River" by
Dr. John C. Geyer, et al. [i] as a guide, studies were instituted to
determine the effects of bentKic deposits, nitrification and phyto-
,plan]rton activity on the dissolved oxygen balance in the estuary.
*Formerly the Chesapeake Field Station
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LOCATION MAP
_1*\
»c<-
»o
' MAHSMA, , HA, OOObt
f MAjOR WAS'i THEATMCNT PLANTS
tSTiJAHY StGMJNI
A'.AOINO STAT.ON
POTOMAC WWtB ! WASHMOTON, D C
A DISTRICT of COLUMBIA
« AAUNOTON COUNTY
C ALfHAHOUlA lAtMTASY AUTHORITY
C FAIWAX COUNTY - WESTGATC PLANT
E FAIHTAX COUNTY - LITTLE HUNTING CPEEH PLANT
r BURWx COUNTY - OOOUE CREEK PLANT
G WASHW6TQN SU»URg SANITARY COMMISSION - PlSCATAWAY
V-O-e>
POTOMAC ESTUARY
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Investigations were also made to determine sources and rate limiting
concentrations of various measurable nutrients which, if controlled,
could alleviate eutrophir condition!-- in the upper Potomac Estuary.
Th L." ri'jxirl includes an asi;ra;'iw nt of U>e current ( ll|r>H) water
'i-iality conditions and factors affecting water quality in the upper
Pctomae Estuary. It includes the sources and effects of the nutrients
on the production o;' massive pnytoplanJcton growths; and, finally, it
contains an evaluation of all major sources of carbonaceous and
nitrogenouii BOD including wastewater discharges, benthic background,
and phytoplanJcton growths and their tffects on the DO balance.
This report Is one of a series prepared by CTSL on various
aspects of the water quality management in the Potomac River Basin
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II-l
CHAPTER II
CURRENT WATER QUALITY CONDITIONS
The water quality conditions in the Potomac Estuary are mon-
itored, usually weekly, by CTSL and by the Department of Sanitary
Engineering of the District of Columbia. The results of the mon-
itoring program for the Months of May through October 1968 are
presented herein. The fresh water inflow., water temperature, and
solar radiation for the six-month time period are presented in
Figure II-l.
A. Fecal Coliform Densities
As can be seen in Figure II-2, high fecal coliform densities,
over 1000 MPN/100 ml, were detected in a reaoh of the upper estuary
from Memorial Bridge (River Mile 4.8)* to Piscataway Creek (River Mile
18.0). Fecal coliform densities over 10,000 were also detected princ-
ipally in the reach between Bellevue (Rivei^ Mile 9.7) and Woodrow
Wilson Bridge (River Mile 11.8). The fecal coliform water quality
standards for the water.- of the Potomac Estuary are 240 and 200 MPN/
100 ml naximum for Maryland and the District of Columbia, respectively.
In the middle reaches of the estuary below Indian Head (River
Mile 29.5), the fecal coliform densities were below 10 MPH/100 ml.
No routine bacterial analyses were made in the main channel of the
lower estuary.
* River miles are the distances measured downstream from Chain
Bridge.
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FRESH WATER INFLOW, WATER TEMPERATURE, and SOLAR RADIATION
I0.00i)
UPPER POTOMAC ESTUARY
MAY to OCTOBER 1968
£
I f,
-------
FECAL COLIFORM ISOPLETH
(MPN/IOOml)
UPPER POTOMAC ESTUARY
MAY to OCTOBER 1968
CHESAPEAKE TECHNICAL SUPPORT LABORATORY
MARYLAND PI
1000
JULY
AUGUST
SEPTEMBER
OCTOBER
FIGURC II-Z
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II-4
B. Dissolved Qxygen (fjQ)
The dissolved oxygen levels in the estuary from Memorial Bridge
(River Mile -4.8) to Hallowing Point (River Mile 26.0) were usually
less than b.O rag/1 as presented in an isopleth* in Figure II-3.
During the months of July through October, when the fresh water flow
into the estuary was less than 2000 cfs, the DO in the reach from
Hainee Point (River Mile 7.4) to Dogue Creek (River Mile 22.4) often
dropped below 4.0 ng/1. Periods of less than 2.0 fflg/1 dissolved
oxygen concentration were observed In the reach from Haines Point to
Broad Creek. The DO water quality standards for the waters of the
upper Potomac Estuary are an average of 5.0 and 4.0 ng/1 for Maryland
and the District of Columbia, respectively.
In the upper part of the estuary near Fletcher's Boat House
(River Mile 2.0), the DO was usually 8.0 ag/1 and greater. Generally,
dissolved oxygen concentrations between 6.0 and 8.0 mg/1 were de-
tected in the middle part of the estuary from Indian Head to the
Route 301 Bridge (River Mile 67.5)..
.
An isopleth, which exhibits a complete graphical presentation
of water quality with respect to location and time along the
estuary, is useful for depicting variations of a parameter
at a given location for a specific time or for a given tine
period along the estuary. The isopleths were constructed by
plotting all data for a given station along the estuary for the
six-month period. A smooth curve was fitted to these data as
representative of "average" conditions during the entire survey
period.
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DISSOLVED OXYGEN ISOPLETH
Ug/l)
UPPER POTOMAC ESTUARY
MAr I-, C\. T.J8ER 1968
CHISAPEAKF TECHNICS SUPPORT LABORATORY
' j
FiGURE 11-3
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II-6
'>. Biochemical Oxygen.D^a&od 1BQD)
1. Sources of BOD
The four principal sources of BOD in the estuary are:
a. Wastewater - carbonaceous,
b. Wastewater - nitrogenous ,
c. ALgal - carbonaceous and nitrogenous, and
d. Benthic-backgrounc - carbonaceous and nitrogenous.
The carbonaceous and nitrogenous BOD, including nutrients
from the wastewater discharges, were routinely Monitored by the
personnel of the various treatment facilities and were intensively
sampled during the special surveys of August 19 to 22, 1968, and
February 11 to 13, 19&), by CTESL, A tabulation of the wastewater
treatment plant BOD and nutrient loadings for the August 1968 survey
is presented in Table II-l. A sunwiry of BOD and nutrient loadings
from wastewater discharges and the fresh water inflow for the
August 1968 survey is presented la Table II-2.
2, BOD Concentrations in tie Estuary
In the reach froit Chain Bridge (River Mile 0.0) to Piacataway
Creek (River Mile 18.0), the BOD concentrations were increased from
an average of 3.0 tog/1 to over 10.0 njg/1 and greater at tines by
wastewater dischargee (Figure II-4). The high BOD level in the reach
from Piecataway to Indian Head was due primarily to algal carbon.
This will be discussed later in this report.
*BOD is 5-day BOD at 20°C unless stated otherwise.
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II-V
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TABLE II-2
SWUARY OF BOD AND NOTRIEHT LQADDOS
Upper Potoaac Estuary
Ai«u0t 19-22, 1968
II-8
Parameter
Flow
BOD
TOC
TKN as N
as N
NH3 as N
TP as PO,
Ibs./day
Ibe./day
Ibs./day
Ibs./day
Ibs./day
Ibs./day
ffastewater
Discharges
334
130,000
101,000
52,800
insignificant
27,500
61,300
Freeh Water
pr^fjQW
1,780
52,800
87,500
U,500
1,500
1,800
4,800
* Based on flow and concentrations for Potoaae River at Little Falls
TOC, = Total organic carbon
TKN - Total KJeldahl nitrogen
TP = Total phosphorus
-------
BOD ISOPLETH
(mg/l)
UPPER POTOMAC ESTUARY
MA^ - . SUPPORT LABORATORY
14 tk SI. B. /^~*\
AUGUST
SEPTEMBER
OCTOBER
FIGURE 11-4
-------
11-10
D- Nutrients - Phosphorus and Nitrogen
1. Sources of Nutrients
In 1966, an extensive sampling program was initiated by CTSL to
determine the sources, spatial distribution, transport mechanisms,
etc., of nutrients in the Potomac River Basin [8], The delineation
of the sources as presented in Tables II-3 and II-4 indicates the
following for an average stream flow year:
\ t ''
a. Of the 93^,600 Ibs. per day of total phosphorus as
PO, which enter the surface waters of the basin, over 92 percent on
the average comes from wastewater discharges. /:,
b. Of the 93,600 Ibs. per day of PO^, 62,000 Ibs. per
day or 66 percent enter the upper Potomac Estuary from wastewater
discharges.
c. The total loading of nitrogen as N to the surface
waters of the basin from all sources is about 152,700 Ibs. per day,
of which 65,300 Ibs. per day or 42 percentar* from waatewater discharges.
d. About 36 percent of the total nitrogen loading is from
wastewater discharges in the upper Potomac Estuary. . ^ f
I If
' -'b
Another important aspect of the nutrient problem in the upper,.- -. c-
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in the upper estuary are relatively uniform when compared to the
great variations in loadings from the upper Potomac River Basin. As
can be seen in Table II-5, the average monthly loading of nitrite-
nitrate nitrogen can vary from 17,400 to about 174,800 Ibs. per day.
-------
-------
11-11
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11-13
TABLE II-[
;?>Ei\I(7;?;i} AVERAGE MOI.T'ILY MH-RISKl LOADINGS
iKTlOMAC RIVER
:;EAR \/ASHINGor;, ;. ::.
"KI: ac :: r.o0+i:o as ;:
(IPS./da, ) (ibs./da; ) (ibs./dey)
!:-' 1 - ' 26,130 >,..20 08,600
Fee. ItS.j-^C 33,151 11,610 121,000
flare I' 21., Jr- «*3..870 14,140 174,800
13,530 161,000
10,340 97,400
15,420 6,f8c 44,370
3,900 4.610 21,600
: 6,11- 10,180 5,o6o 25,760
,'" ' - , - '.-5'6C 4,100 lf,400
f'.jJ- 10.5&0 5,200 27,060
v- o.f; 11,100 5,580 28,800
c- ;J.-V>6 17.959 7,540 54,200
* '
ll,12t: 2l,i3o 3,1 >'5 ' 71,830
eroge moir1 hi;- fl7,;s edjusled f-,r diversions.
-------
11-14
These variations are more pronounced when daily values are
considered. For example, in August of 1966, with a flow of about
XO cfs entering the estuary leas than 1000 Ibe. per day of
phosphorus as PO and NOp+NO., as N entered the upper estuary from
the upper Potomac River Basin, while in February with a flow
greater than 40,000 cfs, about ^8,000 and 354,000 Ibs. per day of
phosphorus and N02*NO^ nitrogen, respectively, entered the estuary.
The transport mechanisms and rates for the varying nutrient
loadings in the Potomac Estuary are currently under Investigation
by CTSL.
2. Nutrient Concentrations in the Rstuary
As presented in Figure II-5, the total Kjeldahl nitrogen (TKN)*
concentrations are the highest in the reach from the 14th Street
Bridge (River Mile 6.0) to Indian Head (River Mile 29.0). In the
upper estuary near Woodrow Wilson Bridge {River Mile 11.8), concen-
trations of 3.0 mg/1 and greater were observed in July and August.
The end product of the oxidation of TKN is nitrite-nitrate
nitrogen. As shown in Figure II-6, the high concentrations of
N02+NO-J (above 1.5 mg/1) are farther downstream and there is a lag
in time when compared to the level of TKN in the estuary. The sig-
nificance of this oxidation process is discussed latter in this report.
*TKN parameter includes both organic and NH~ nitrogen.
-------
60
TKN as N ISOPLETH
(mg/l)
UPPER POTOMAC ESTUARY
MAY to OCTOBER 1968
CHESAPEAKE TECHNICAL SUPPORT LABORATORY
1.0
JUNC
FIGURE 11-5
-------
NO2 * NO3 as N ISOPLETH
(mg/l)
UPPER POTOMAC ESTUARY
MAV »o OCTOBER 1968
CHESAPEAKE TECHNICAL SUPPORT LABORATORY
10
PISCATAWAV C
WOCX)ROW WILSON Br
Btl LE/UE
SEPTEMBER
OCTOBER
FIGURE li 6
-------
ii-r.
T:.e TKN and NOj-'NO-, concentrations of the water entering the
estuary during the months of July through October were about 0.7
ana iers than 0.1 mg/lt respectively.
Tt.o phosphorus ;>oncontrations wero similar to TKN levels
during the period from May through October (Figure II-'.'). During
Uir iioiithr oi' August, September and October, the concentration of
phospnorus was 2.0 mg7! and greater in the vicinity of Woodrow
Wilson Bridge.
Tr.e concentration of phosphorus in the waters entering the
c-stuary varied from 0.1- to 0.^2
-' Aigal r. yanding Crop
Using chlorophyll "a1' as a measure of algal standing crop, the
isopleth as presented in Figure II-6 indicates that there was a wide-
spread bloom* in the Potomac Estuary during the sunnier months of
19*36. For the month of August, chlorophyll levels of 150 pg/1 and
greater were observed from Bellevxie (River Mile 9.7) to Hallowing
Point (River Mile 26.0).
During the months of May and June, the predominant algal species
in the upper estuary was Chlamydomonas sp. , a green flagellate. During
the months 01 July through September the predominant species was
Anacystis cyanea, a coccoid blue-green algae. During the month of
November, the predominant phytoplankton was Chlorella. a coccoid
green algae.
*When chlorophyll levels are j>0 -g/1 and greater, bloom
conditions are assumed to eaist.
-------
TOTAL P as PO4 ISOPLETH
(mq/l)
UPPER POTOMAC ESTUARY
MAY »o OCTOBER 1968
CHESAPEAKE TECHNICAL SUPPORT LABORATORY
MA»VIAND PI
KEY Br
JUNE
-I 1
AUGUST SEPTEMBER
OCTOBER
FIGURE 11-7
-------
CHLOROPHYLL ISOPLETH
g*g/D
UPPER POTOMAC ESTUARY
MAY to OCTOBER 1968
CHESAPEAKE TECHNICAL SUPPORT LABORATORY
SO
11 30
AUGOST
SEPTEMBER
OCTOBER
FIGURE 11-8
-------
III-l
CHAPTER III
NUTRIENT-ALGAL RESPONSE
AND ENVIRONMENTAL REQULROENTS
As pror.ented in Figure II- ;, the chlorophyll Bevels during
ii.c month;; of Jtjie through October 1968 were generally greater
than r-0 uE/i for approximately 50 miles of the upper estuary.
.Similar enlorophyi.. levels were also observed in the upper
ci;Li,ary during cianmer months of 1965, 1966 and 1967.
In an effort to determine rate limiting concentrations of
various; measurable nutrients, which if controlled could alleviate
the eutrophic conditions in the upper Potomac Estuary, an analysis
of data from intensive surveys and routine monitoring stations
haf beer, undertaker, at CTSL. Statistical analyses were also
made on other areas for comparison as presented in Table III-l.
In tne analyses, the following parameters were investigated:
1. Total pnosphorus ". Temperature
2. Inorganic Phosphorus 3. Secchi Disc (measure of
light extinction)
3. N02-Nitroge.-
9. Nitrogen/Phosphorus Ratio
4. NoNitrogen
10. Salinity
5. TKN-Nitrogen
11. TOC
6. NH,-Nitrogen
-------
III-2
IiI-1
Lj, DA;A
11
c :rsc
l.io-l. 8 CFS, FWPCA
-------
III-3
By grouping the data, the physical effects of fresh water in-
flow, channel-depth, tidal velocity, salinity, etc., on the
algal standing r* rop were also investigated.
»
Preliminary results of the : .iiistlcal ,«naly.- ey for the
Potomac Estuary and the other eutrophic areas are presented
below.
A. Phosphorus
A nutrient which has been often related to nuisance algal
blooms is phosphorus. To determine if increase in algal growths
in the Potomac Estuary is related to the high phosphorus leveLs,
analyses Of the data from the years 1965-1968 primarily for
the summer conditions were nade.
Figure III-l is a graphical presentation of the chlorophyll-
phosphorus relationship developed by plotting the mean phosphorus*
versus the mean chlorophyll levels for the various areas indicated
in Table III-l. From the graphical presentation, it appears that
when the phosphorus level is below 0.6 fag/l growth-dependent
conditions occur (i.^., under these conditions, the chlorophyll
level or standing stock is directly proportional to the phosphate
concentration present). Above 0.6 mg/1 of phosphate, the chloro-
phyll appears to be constant and independent of the phosphorus
*In this report all phosphorus concentrations are given ae
total phosphorus as 1*04 unless stated otherwise.
-------
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FIGURE II I-I
-------
concentration.* Similar observations with regards to growth
response have leen made by Borchardt and Azad (9)in studying
phosphorus uptake by algal cultures in the laboratory.
In Figure III-2 ie exhibited chlorophyll Inorganic pliosphorvus
concentration tor the 19Gc summer intensive survey t>y CTSL.
: unripling stations in the Potomac Kstuary are shown in Figure 1-1.
T.'.c relationship is very similar to that of the entire Chesapeake
May system, as presented in Figure III-l.
From tne relationships in Figures III-l and III-2, it appears
that nuisance algal bloom (above 50 ^/l of chlorophyll) ?an be
reduced significantly in the Potomac Estuary if the total phos-
phorus level is maintained below 0.3^ mg/1 as PO, or in terms of
inorganic phosphorus, 0.30 ag/1. This ia assuming that all other
algal growth conditions are favorable.
1. Nitroger.
The analyses of nitrogen-algal relationships are more complex
than phosphorus-algal responses in tnat the predominant form of
nitrogen entering the estuary can LC either NHo, NO-< or organic.
-} .;
During spring high flows, the nitrate-nitrogen form, primarily
from land runofi. ih the most abundant.
Coupled to varying forms of nitrogen entering the estuary are
tne biochemical dynamics of the nitrogen cycle itself. During the
*Above this concentration, "luxury uptake" of phosphorus occurs.
-------
FIGURE III-2
-------
III-Y
summer months, most of the ammonia and some of the organic nitrogen
from wastewater discharges are oxidized to nitrate-nitrogen as
exemplified by the A<;gust 1468 survey. (See Figure III-3.) The
nitrate form it-- tnen token up by th- uV^e wiu eonvrrted into
organic nitrogen as part of the cell.
Mass balances of the various nitrogen fractions, phosphorus,
and chlorophyll were made utilizing the data from the intensive
rurvt'vs. The (mlar.ces, or mare specifically, instantaneous loading
rates, were calculated by the formulation as presented below:
P ^ L x A x C x F
where
P Loading rate in a given cross section (Ibs./linear ft.)
L One linear foot of estuary (ft.)
A = Cross section area (f t )
C r Average concentration of parameter in cross
section (mg/1)
F = A conversion factor
The dynamics of the nitrogen system are shown in Figure II1-4,
which is a graphical pi "-sentation of the instantaneous loading
rates for the August 19-22, 1968, survey. From River Mile 0.0 to
River Mile 10.0, there is a rapid increase in TKN and NHo loading.
Starting at River Mile 2.0, the nitrate loading starts to increase
with a maximum loading rate at River Mile 20.0 which corresponds
to the minimum loading rate of NH^ downstream from the wastewater
discharge.
-------
O
I
I
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O
cx
O
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c
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a
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-------
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avoi
FIGURE 111-4
-------
Ill-10
In the reach from River Mile .30 to 50. the nitrate loading
decreases to less than 1 lb. per linear foot. 17 is decrease in
r.i-.rate is attriouted to utilization :y the algal cells.
T'ie mtKii tnlRncrr SB presented ir, Pi^ure III- * also indicate
trial most o! the phosphoruf moves, downstream. I'hir, constant loading
rare for phosphorus corroborates tne works ci Hayes [10] in which he
stated that the recycling time of inorganic PO^ :-y phytoplankton
;ir.c; i/acterial cells ir very short, less than one day. Mass balances
i'-r other survey;? indicate similar downstream .Tjoveiuent except in
the upper estuary during periods of low flow. Und^r low flow con-
ditions, the concent rat ion of phosphates is often above 2.0 tag/I and
considerable depositions occur. Deposition to the bottom muds occurs
at Lower phosphorus levels in the middle and lower portions of tne
ostuary as supported oy data from recent Potomac Eetuary sediment
surveys; however, the rate of deposition is much less at low concentrations,
In Figure III-5 is a graphical presentation of the nitrate nitrogen-
chlorophyll concentrations for the same conditions as in Figure III-l
for phosphorus. Wr.er. the areas witn phosphorus concentrations of less
than 0.39 mg/1 are noted, the relationship between chlorophyll and
inorganic nitrogen appears to be significant.
For the lrmb and 1966 intensive surveys in the Potomac Fstuary,
the relationships 01 chlorophyll to N02*NO-3 nitrogen are more pro-
nounced, as can be seen in Figure III-6. Moreover, the relationship
is linear with no point of "luxury uptake' as with phosphorus.
Using the W ug/1 of chlorophyll level as for phosphorus and
the relationships in Figures III-5 and III-6, maintaining of
concentrations o,' less than 0.35 rag/1 of N02*N03 nitrogen as N
-------
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-------
111-13
rhould alleviate nuisance phytoplanJrton conditions in the Potomac
Estuary. Again, this is assuming that no other vital system Is
ra t,e-limi ting.
ALso, It. analyzing th<> data : rom the i^u^-l1-^ Potomac
Kstuary surveys and monitoring stations in the ChesapeaJce Bay,
:,ne following observations have oeen made:
i. During the periods of low flow in tne summer months,
nJ»-'h chlorophyll concentrations and high NQ^+NG^ (end product of
the oxidation o: NKo) ueually occur in the same reach of the upper
Potomac Kstuary. This suggests that nitrogen could be limiting
the total standing crop; however, more studies are needed to
determine the significance of this simultaneous occurrence.
2. In the lower part of the estuary, and in the Chesapeake
Bay, a significant relationship between TKN and chlorophyll was
established for summer conditions. Mass balances in the Potomac
Estuary for 19o6 and 1968, indicate a continued increase in TKN
loading rates in the upper }0 to
-------
III-H
rate for TKN was increased from about o.O to over 13.0 Ibs. per
linear foot. (Gee figure III-A,) This suggests that fixation of
nj l.ropen from l.he atmosphere was significant. IT all this TKN
was from nitrogen fixation, the amount of nitrogen was atout
equivalent to that from the wastewater discharge loadings.
C. Qtfeer Oojislderatipng
]. Stream Flow
In the Potomac and the Patuxent* estuaries, the effect of a
large increase in fresh water flow on reducing chlorophyll has
oeen observed on numerous occasions.
Reduction in chlorophyll levels r,y a sudden increase in stream
flow is attributed partially to dilution, dispersion and seaward
displacement. In the Patuxent River especially, suspended sedi-
ments appeared to remove some of the algal growth by accelerating
the settling of the cells.
During September 1966, after the lowest flow of record entering
the Potomac Estuary (150 cfs), chlorophyll levels of over 200 (j,g/l
were reduced to less thai. 25 ^g/1 by a rapid rise in flow to over
27,000 cfs. Similar observations were aade in the Patuxent during
July of 1968.
2. Temperature, Solar Radiation, and Light Extinction
The effects of temperature and light conditions on algal growth
have been well studied in the field and in the laboratory (11) [12],
*The Patuxent River Basin, lying within the State of Maryland,
is about one-tenth the size of the Potomac.
-------
IIt-1')
/We-ife temperatures In t:,e Pcto~«ec Frtuary for tnt- uontns of May
',:.r< -\ipn Octo.-^- ran*:? from 18CC to 28°C. When the temperature as
; ' !,tci1 ! .' .L ;>"ur-«- ; l ~ \ 15 -onr^.H r»> rvph.v ' "«'' Hf. .:tiown
-?x ifn^i v algal f ,-<>wUi: in the
i < i ciiiHC1 Ks tua :\» .
Anal.vFer. c; li»;ht, intensity aata such as T.urtidity ana .'"e
r;iSf readirurr wi'.ich could affect tr.e algal stancin* crop have
irdicnted no .< r.fitis tically significant relationship,
'*.. Oth»-.- r.virorimental Parameters
Many other environmental parameters such as heavy metals,
:»!lir;ity. nri^v-nutrier *,f , etc., wr.icn fnay nave some efi'ect on
RlK^i growth;' ire either currently under study or nave been in-
corporated into the 19;l-7^ program plan of the Middle Atlantic
.we^ion, FWPCA.
-------
IV-1
CHAPTER IV
ORGANIC I LADINGS IN THF UPPFP AND MIDDLF ESTUAPIFS
The BOD concentrations in tne upper estuary as shown in the
h in Figure H-A are greatly increased :.y wnstewater dis-
charges from the Washington metropolitan area. To aid in the
a«"Kif;r, oi treatment facilities, a study of the magnitude and sig-
ni licence 01 <'«ch ol tne sources o: BOD and other organic loadings
ai: presented in Chapter II was undertaken.
In Figure IV-1 the measured i>-day BOD and TOC concentrations
during the intensive survey of August 19 to 22, 19t>8, are shown.
Ti e corresponding nutrient and chlorophyll concentrations are
presented in Figure III-2.
The major difficulty in quar.titating the significant sources
of HOD is that, the 5-day BOD determination is a composite of all
four sources. The discussion that follows is an attempt to quan-
titate the various sources of 5-day BOD in the upper and middle
entuary.
A. Algal Carbonaceous and Nitrogenous BOD
E>uring the growth phase, phytoplankton have been shown to
nave considerable diurnal effect on the oxygen balance as a result
of photosynthetic oxygen production during the day and the
"take-up" of oxygen by respiration at night [13] CUJ. In algal
-------
"*i"
.1 |
/
-------
M'-t . K"(5 :oinputed i;^ ;,". treti^a^ ^L
yt' r- a; Kaon growth nevrrv a -a ncentrat^on >» i.C^£/l o;
.: " - <' .'i!v».t .).«''; tii . ..; carbon ar.d nitrogen
ri(:' : ^o; ' r i t>u ' . »;. ' li'.''1 aiafif-' i o pr> tvp.ankton
. r. i?" Poionac ^ ;uary. statist. CH! s'.uaiee ir^r'-
h,"c;.:ii^: stations in th*> low»>r P^v>aa.'? anc "nps;-~
wt'V re , H ' . f.rfUj. *«£ oeveiopec lor f.he low?: -'ntuary;
K)C - ..'J * 0. :.' .cro
'i-C t)-"ay ;<'L '; ,T , d - 2 nanjne 1 deptr^ s rag/1)
::iorc ch^orcDh ^ , n^entraticr, at -,re water
surface . ,. ,
";.rti>»=, .fll'Tj- utiiizir)£ r'. ." '>',a ir,jlca-i^d r.nat most o; ,\
. j. ?or.tr: u* lor- to HOE was ' !or3; O; ^arc.or, . Kor the lowr
- rvic :-.r, i -j .- r .' , t:.' r'oliowin^ -< . at . or^hip *«u; efitac ; ished for
jrrer conai it iis :
hCD =- 5-clay EX3r at rr. 'd -channel aep-.h (nag/1)
TOC = total orpar.n- -jaroon at mid-c.nannel
depth (mg 'I i
Uitimat" oxygen aemBxsc [.K>. cons.ots 01' the s\irr, of the caroor.
aceous er.d nitrogenous BOD as *_./en belo»:
roc - 2.6°" r. + L.^ i.
wherp
- " -unox id i zed r; t ro^en
-------
j B chloropfiyi I level c:' 100 £/ 1 :r substituted into first re-
lationship, s MOD of «;. 5 ffi£/l is jl*ain*>d. This is considerably
M-f-p ' hm. the ' heoret.ical bOtsl ox,,ve: demand which would be
.' *. nv/1. Frirn the above anslyt.ir, and *he TKN u>nd rat* curv*>
i: F.gure III-?, it appears that oxidation of t/.e organic nitrogen
ooinponent of waetewater and of phytopianxtxsn fells does not occur
VCT/ rapidly. "imilar oteervations on tne slow remineralization
oi jiitrog^n corapcjundt from phytopiaructon have oeer. made by
u<'ttennan [1 | and Harvey [!"'.
Using th«? aoove two relationships, the anaount of 5-day BOD
nttr/ruted to th»- algal Ptanding crop wa* determined. Tne algal
BOD was then s . >t,rsctec from measured i--day BOD (^urvf A) as pre-
j^pjited in Figure IV-1 yielding curve K The majtiUiUin contribution
from tne Etandirv crop was at River \Li*.' ^'".0 where the 5-day BOD
wac atiout ^.0 n^;'l.
' 'Aastewater arbonaceoiLB BCD
Tre contri r ution of f>-day carionaceoi^ BOD ; rom the wastewater
discharges was determirjt-1 ty routing the loadings as presented
in Tn1- le H-l ir, a mathematical model of tne upper estuary [4J.
Trie fresh water inflow and other model parameters were cased on
observed conditions during the August 19-22, 1968, survey.
r>e wastewater carbonaceous BOr contribution was subtracted
from '.-urve P to determine curve C ir. figure IV-1. With ?7'-'0 cfs
-------
rv-'
r. _ r. v-\i'~ ;:",( rl:u- tne c-Kt ^jr . ::».> -aax inxjE increase from
»'-.r Mj»-rn^" ^"LOTiareo-zi 30/1 wa£ 3." <:;*>. <. . "' mg-'l at Fiver U'.le II.
'I-*: - . nv.it, » o> y; ei ciecvu. . . >K :: , t.r.e r : t r->f;o;.x> js rrf)]"1 caii
; "ed . : ol ,1 )*?=
w, >-r
;JOI> aj ', . nti 1 1- r,i t,ro^er!O'is oxyr*?n demand ''mg/1)
^r,o . i a i z ed ' . ; t ro;: PI . rvr / 1 )
T' jv--- < \pr ;.3:or: nar ^een verifJed ir, T,he laooratory and in
*, < : ic-ic ' ; - s ->:,]
">.<- inoir : c- : i - .-ification ^r -,r.e '-day BO," usually is con-
.<- laired txr, :e i:^ if-iul leant . rfc^r.i stucies >:y CTSL indicated
hat in r.igr.ly r,_. :. rifled water sucr «.3 :he patuxent and Potomac.
thf o:% lly free from ir^, was^pwatf-r ^i-'urn^s, the following relation-
3.'; NH-j-J1. + 0.0} Chloro
30Dr c--diiy BOD concentration (njg/I)
'JH7-A' - Concentration of KK- nitrogen (mg/lj
'.:nior'~ - '>,lorophyll concentration (j_g/l)
-------
IV--
":.< .' ':onr'fc.-t .or MH-.-S ^ . oniewh-! .owe:- r ar. the
. uc o: ... . Tr,= c i f;~f "-::-- (u.-; > duo to NTi n. st t
>' .' i' fi ' ! i ' i.. ,'K; .'X i j i ! ((.' , -v I"1 : a; ;:»'.' »Ml f t'O ! I. f tn
." -yt ^>-'c; , i;- c"..: ' r'it "»eo r'rr^ni ^i.r ,, the ajaouj *. ;; '.r.f- ccn-
:' lioi, U) ",-aa. . OD : /x)ra tne :.i'r fie* tier, process ,£ ODtair/eu
,"jr" IV- ,, "r <~> ".argest c: : :'^re:ice of 2.4, mp, i '(tvi^cr. ih^ LW<
''.-''.'" ?:* ,'/' U, , I1-. '.' vi/.c.I/ "TIT." irH'^e.'"; tr.p ":on*,ri uutio? :'
' r l-xi,'1- -/. u." rx-j>'i :. C' mfir»a .n tf ? !:-day W)L . 7:" ei'l'ect cf
: trli'ication on X :alar.ce i;; preser.ted later in this chapter.
- Bentnic-gac'--^. w .u . . ^ynac^-ou^ aiid _N.
; (eg a r Ji ir^-r with r . - ag/'i at :'.'ver Mile 0.0 and gradually de-
- r-oa-sing tc- 1.^ ing. 1 at r'aver M.. le '"', a benthic-Dackgrcamd liOD
-:rvf- D) w-if «-.-.-: --^ from mea^'-rf-c ^-day RCi:. This POD, wr.Jr
'-a: .:; part rr- attributed *^o sludge o '-posits, u{;£^rearo loadir^:?,
N.; loading.1" :'ros the cottoa a epo." :*,=--, etc., is both carbonaceous
-'«':a nitrogenous. \'o attempt r.ap "''fen made to fraction this s
r- L'xfyg_fer. _ Demand C
In ! ;,--.. re- IV- 1 the delineat icr. of ;or "learly demonstrater
iO* much and wherr each of four T£, or r.ourcer cont-ic'utes to
t!-- 'xotal 5-day BOD Ir, the upper estuary. A somewhat different
> -:.' pccti ve of trie FOD sources i; ort&ined when tn^ U'OD sources lor
-------
t:,>-> upper prt :ary between Chain hridge and Indian Head (River Mile
"''.') are compared as tabulated r-e". ow;
ources UOI)
fibs, 'day)
AastewoT'-r - carbonaceous irf
tf,- - readliy oxidizfic^e
r.itropenous (NH-?-N) 125,000
*astewator - lore readily oxicizabie
nitrogenous (organic-N) 11<.,000
ALgal-caruonaceouf and nitrogenous 400,000*
iind - carbonacec.^ and
nitrogenous AD, 000
K₯X)iT! -he n?K5ve tabulat.or, i*. car. :" "»-adily seer, that the major
Dourer o;' IX3L- .: the upper ertuary ,. : :x>m ohyt-oplankton with the
3U.T. op wastewster nitrogenous BGI- .''"ond. wastewater carbonaceoi^s
BOD third, and "rc^ithic- background icurtn.
Balance
A schemata? aiagrair. in Figurt I'. -*' originally presented by
Tf-rpey [ 22] snows the iiiterreiation.sr.ipc o. the oxidation of cartxjn-
ooeous ana n.r tro^e-nous organic raatier, p.totos^Tithetic activity 01
p/.y!nplanJftor. , ar.a dissolved oxygen. Ir the upper Pc-tomac Estuary.
these three b.'oiofical systems car. ar.d do occur simultaneously in
on t:.e -imovjit cf y-day BOE' required to increase the BOD
.0 ng/1 in *.ne upj^er estuary. Thif- value can be considered
ronservativt.Ay low.
-------
lONDOMOMDVB - JIH1N38)
FIGURE IV-a
-------
the same reach- oxidation of wastewater and algal carbon; oxidation
of wastewater KM,; and photosyntnetic activity.
Tf pro' :i>- tor trie Intensive survey during August ol 1968
nas three distinct depressions in tne upper estuary corresponding
to the three ^clogical systeraB. Trie firet large depression at
M ver Mile 11.' vras mainly due to the oxidation of wastewater car-
i>onac .jous BOD. The second depression at River Mile 20 was caused
primarily by oxidation of the wastewater nitrogenous BQD. When
compared to the nitrification in eitner the previous or succeeding
two-week period, the DO depression in this reach was considerably
if-r; ae a result of a 50 percent increase in fresh water flow into
the estuary during the intensive survey. Tnis reduction in nitrifi-
cation can be seen clearly in the NO^+NC-, isopieth in Figure II-o.
Tne snarp increase to .1 rag/1 near River Mile 26 was probably
a result of oxygen production by al^ai cells which were at their
highest concentrations in the estuary at this point.
In the reach from Piver Mile 2t> to 35, the 1.5 mg/1 DO depres-
sion is attributed to decay of the algal ceils. .A secondary
recovery in DO towards saturation values begins at River Mile 35.
-------
V-l
CHAPTFh V
CURRENT AND PROPOSED INVESTIGATIONS
As indicated in Chapters III and IV. the four major areas
currently beiiig studied oy CTSL in regard to the Potomac Estuary
are as follows;
1. Nutrient-algal relationships,
2. Hole of nitrification in DO Balance,
'}. Nutrient transport mechanisms and rates, and
4. Dispersion.
The data and interpretations presented In this report are to
provide a basis for current planning of waste treatment facilities
to achieve water quality ^standards. Studies will be more extensively
developed in four separate reports covering each of these areas.
Three field studies which are to oe initiated in the near
future are;
1. Fate of algal carbon fixation and oxidation,
2. Nutrient-algal rate limiting studies, and
3. Nutrient exchange rates with sediments.
The four current and three planned studies are all designed to pro-
vide data for the development of a comprehensive plan for water
quality management for the Potomac Estuary.
-------
REFERENCES
1. Geyer, J, H., Carpenter, J H., Pritchard, D. W., Renn, C. F.. ,
Scott, D. C., and Wolman, G., "A Research Program for the
Potomac River." Johns Hopkins University, 1966.
2. Hetling, I. J., and O'Connell, r. L . 'A Study of Tidal Dis-
persion In the Potomac River,'' Water Resources Research.
Vol. 2, No. 4, Fourth Quarter, pp. 825-641, 1^66.
'). G'Connell, H. L., and Weeks, J. W , "An In-vcitu Benthic
f^espirometer," CB-SRBP Technical Paper No. P. Federal
Water Pollution Control Administration, Middle Atlantic
Region, Charlotteeville, Virginia, 1965.
4. Hetling, L. J., "Water Quality Model* of the Estuary,"
Appendix A, The flange of Choice in Water fieeource Munageaent:
A Study of the Potomac Estuary by Robert K. Davis, Rceourcee
for the Future, Inc., Washington, D.C., 1968.
5. Hetling, L. J., "Simulation of Chloride Concentration In the
Potomac F^tuary," CB-SRgP Technical paper No. 12. Federal
Water Pollution Control Adalnistration, Middl* Atlantic
Region, Charlotteeville, Virginia, 1968.
o. Jaworski. N. A., and Aalto, J. A., Wastewater Inventory,
Potomac River Basin," Chesapeake Field Station, Federal Water
Pollution Control Administration, Middle Atlantic Region,
Charlottesville, Virginia, Dec. 1968.
7. Aalto, J. A., "Statistics and Projection, The Potomac Estuary,"
Winter Public Meeting Proceedings. Interstate Commission on
the Potoaac River Basin, Fredericks burg, Virginia, 1968.
8. Jaworeki, N A,, Villa, 0., and Donovan, G. R., "Nutrients
in the Potomac Rive/ Basin," Chesapeake Field Station, Middle
Atlantic Region, Federal Water Pollution Control Administration,
Charlottesville, Virginia, in press.
9. Borchardt, J. A., and Azad, H. 5., "Biological Extraction of
Nutrients,' Journal of Water Pollution Control Federation.
Vol. -40, pp. 1739-1754, Oct. 1968.
10. Hayes, F. R., "The Role of Bacteria in the Mineralization of
Phosphorus in Lakes," Sympoei.ua on Marine Microbiology.
Charles C. Thomas Publisher, 1963.'
-------
11. Harvey, H. W., The Cheaiatry and fertility of Sea Water.
Chapter V, Cambridge at The University Press, London, 1963.
12. Raymond, J. E G., Plankton and pppductiylty ID toe Oceans.
Chapter I, Pergaaon Press, London, 1963.
13. O'Connell, R L., and Thomas, N A., "Effect of Benthic Algae
on Stream Dissolved Oxygen." Journal of the Sanitary Engineering
Division. ASCE, Proceedings Paper 4345, Vol. 91, No. SA3,
pp. 1-16, June 1965.
1-4. Hall, C. H.. "Oxygenation of Baltlaore Harbor by Planktonic
Algae," Journal of the Water pollution Control Federation.
Vol. 35, No. 5, pp. 587-606, my 1963.
lf>. Bain, H. c. , Jr., "Predicting DO Varieties Caused by Algae."
Journal of the Sanitary Engineering Division. ASCE. Vol. 94,
No. SA5, Proceedings Paper 6158, pp. 867-881, Oct. 1968.
16. Gaoeson, A. L. H., and Wheatland, P. A , "The intimate Oxygen
Demand and Course of Oxidation of Sewage Effluents," Journal
and Proceedings of the Institute of Sew«ge Purification.
Part 2, pp. 106-117, 1958.
17. Gotterman, H. L.. "Studies on The Cycle of Elements In Fresh
Water," Acta. Bot. Neerland. 2:1-58, 1953.
18. Harvey, Chapter III.
19. Department of Scientific and Industrial Research, "Fffects of
Polluting Discharges on the Thames Estuary." Water Pollution
Research Technical Paper No. 1.1. Her Majesty's Stationery
Office, London, 1964.
20. Wezenak, C. T., and Gannon, J J.. "Evaluation of Nitrification
in Streams," Journal of the Sajiitary Engineering Division. ASCE.
Vol. 94, No. SA5, *>roceeding6 Paper 6159, pp. 88>895, Oct. 19o8.
21. Stratton, F. E., "Ammonia Nitrogen Losses from Streams," Journal
of the Sanitary Englreerlng Division. ASCE, Vol. 94, No. SA6,
Proceedings Paper 6282, pp. 1085-1097, Dec. 1968.
22. Torpey, W. N.. "Effects of Reducing the Pollution of Thames
Estuary," Water and Sewage Works. July 1968.
-------
Chesapeake Technical Support Laboratory
Middle Atlantic Region
Federal Water Pollution Control Administration
U.S. Department of the Interior
Technical Report No. 6
SANITARY BACTERIOLOGY
OF THE
UPPER POTOMAC ESTUARY
Donald W. Lear, Jr.
and
Norbert A. Jaworski
March 1969
Supporting Laboratory Staff:
Johan A. Aalto, Director
James W. Marks, Chief of Field Crew
Orterio Villa, Jr., Chemist
Robert L. Vallandingham, Boat Captain
Anna R. Favorite, Statistician
Rose Ann Tilton, Typist
-------
TABIE OF CONTENTS
Introduction 1
S. udy Procedures 3
roraplinp; :Cations and ivograns 3
Analytical iTocedures 5
1. Indicator Bacteria 6
2. Salmonella 6
ClimatolOfp.cal C -nditions 8
Results of Giudy 10
Sources of CJliform Organisms 10
Estuarine W^-ter Duality C nditions H
Discussion 27
Indicator Bacteria in the Potoraac Estuar^' ... 27
Distribution of 3almonellae 31
Summary 3^
Bibliography 35
-------
IISl' OF FIGURES
K'imbcr IX; script ion L';\KC
Sampling "etvork, Bacteriological Survey,
?otonac Kstuary .................. 2
fotonac River Flow at Great Falls }
Bad eriological Survey .............. 9
Conform Distribution Isopleth, Upper
P:rto;nac Estuar^,r ................. 13
Fecal C'jliform Distribution Isopleth_,
Upper ?'tomac Estuary .............. ill
F^cal 3' roptococci .Tsopleth, Upper
.'ntcr.ac Estuarj'" .......... . ...... 15
Galr.'.onella Recover^', Upper ?-jtoraac Estuary .... 16
I::dical or-Bacterial Density and Salmonella
Recovery, Upper Potomac Sstuar;»r ......... 33
-------
1 1 1
UST OF TABLES
I Ju r.ib e r Be s c ri trt. i on ; a,
Description of oanplinc retvork,
Bacteriological Purvey 4
Sa_lnonellag and Indicator-Becterial D?ta,
Uoper -bi o;;iac E.:tuar>r; Jan.-Kiarch 19^7
Chesapeaiie Technical Support Ijaboratory . . 17
Focal Coliform/Fecal Streptococci Ratios
Potomac Estuary, February-l.'.arch 19^7 29
-------
INTRODUCTION
As part of the Chesapeake Bay-Susquehanna R'ver Basins
Project, the Chesapeake Field Station undertook extensive field
investigations to determine the water quality in the ,'Otoraac River
Basin. A significant part of these studies was the determination
of the bacteriological water quality condition of the upper Potornac
Estuary.
A study was initiated in winter 19^7 to:
1. Determine the bacteriological wa1 er quality of the upper Potomac
Estuary;
2. Relate bacterial distributions to other water quality parameters;
3. Evaluate an isolation procedure for oalmonellae;
k. Relate the comparative usefulness of coliforms, fecal coliforrns,
fecal streptococci and Galmonellae as water quality indicators;
5. Identify probable sources of bacterial pollution in the area.
nhe study area encompassed a reach of the estuary above the
wastewater discharge in the Washington, D.C. metropolitan area to
the oyster producing waters of the middle estuary below the Potomac
2;ver Bridge at Dahlgren, Virginia. (Figure l)
-------
LOCATION MAP
SAMPLING NETWORK
BACTERIOLOGICAL SURVEY
CHESAPEAKE
SAY
SCALE IN MILE S
POTOMAC ESTUARY
-------
STUDY PROCEDURES
Sampling Stations and i*rograms
A sampling network of 31 stations was established along
60 miles of the upper 1-otomac Estuary. ',,astevater effluent samples
were also obtained from the four major sewage treatment plants in
the Washington metropolitan area. Figure 1 and ri pble 1 give detailed
locations of the sampling stations and sewage treatment facilities.
Upstream bacteriological samples above navigable waters in
the Washington area were taken from bridges, iced, and returned
within three hours to the laboratory at Annapolis for inoculation
and incubation. For the remaining estuary studies bacteriological
samples were taken to the Chesapeake Field Station mobile camper
laboratory located along the river in positions to receive samples
directly from boat crews. Water samples were immediately inoculated
into presumptive media and incubated aboard the camper, "his proced-
ure was instituted to minimize any bacteriological changes during
the transport, period.
Salmonellae were isolated by an immersed swab procedure [Ij.
Bundles of cheesecloth strips (swabs) were suspended from bridges or
buoys at various points in the river, ".'here the swabs could not be
suspended in midwater due to inaccessability, they were tied to
stakes near shore in one foot lengths of four inch ?VC pipe to mini-
mize contact with bottom sediments. Vhe swabs were usually immersed
-------
TABLE 1
Description of ''tripling ":etwork
Bacteriological Survey
Chesar>eake F'eld nation
1967
LJI at Ion
r1"
x
2
2A
3
h
hA
5
6
7
7A
8
9
10
11
12
13
Ik
15
16
17
18
19
20
21
22
23
2^
25
26
27
28
A
B
C
D
Description
Cabin JVnn Bridge
Chain Bridge
Key Bridge
Rock Creek-;.' St. Bridge
f'emorial Bridge
tilth St . Bridge
Raines . oint
Anacostia River-S.Capitol St.Br.
Boiling AFB - Buoy 9
Bellvue - 23 ft. bell
Blue ilains - Buoy 8
Alexandria Marine Service Dock
Woodrov; V/ilson Bridge
Broad Creek - Buoy 86
Fort Washington - Bank
Fort .ashington - Buoy 75
Marshall l!all - Dock
Dogue Creek - Buoy 67
Hallowing - oint - Buoy 6l
Indian Head - "avy D ick
Indian Head - Buoy 5^
M -ss i-oint - Bank
I-^ssum Point - Buoy Uh
Candy 1-oint - Buoy hO
::rnilh :':int - Buoy 30
Maryland _. oint - Bank
Maryland \ oint - Buoy 19-21
Tlanjemoy Creek - Dock
Nanjemoy Creek - Biioy 11
Aqualand Sea>;all
Cobb Island - Brnk
Blue Plains CTP effluent
Arlington STP effluent
Alexandria GTP effluent
Uestgate oTP effluent
Salmonella
Samples
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Co 11 form
Samples
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
-------
for a period of five days; however, at times the duration ranged
from four to seven days because of weather condilions controlling
the installation and retrieval.
Disposable polyethylene gloves were used in the handling of
swabs during retrieval. The swabs were placed in polyethylene bags,
tightly secured, and iced for return to the laboratory at Annapolis
for further processing. No attempt was made to pre-sterilize the
swabs, gloves, or polyethylene bags. Control swabs, identical in
handling except for immersion, were run in parallel and yielded
uniformly negative results.
A departure from the swab technique was made for the isolation
of Salmonellae from sewage treatment plant effluents. For the efflu-
ents, 150 ml of sample was passed through HA millipore filters*, with
the filters processed similarily to the retrieved swabs.
Analytical Procedures
1. Indicator Bacteria (Coliform, Fecal Coliform and Fecal Streptococci)
The 5~~tube, h dilution MPN technique was used. For presumptive
coliforms and fecal coliforms Difco lauryl tryptose broth was employed;
for presumptive fecal streptococci Difco azide dextrose broth was used.
Incubation was at 35° c.
Coliforms were confirmed in Difco brilliant green bile 2$ broth.
Fecal streptococci were confirmed in Bacto ethyl violet azide broth.
Fecal coliforms were confirmed in Bacto EC medium, incubated at ^5.5° C.
These procedures are outlined in detail in S1 andard Methods |~ 2 n.
k- .J
* HA millipore filter has an effective pore size of O.U^ microns
-------
2.' Salmonella
In the Lnbornl ory eacl' en..'ah was cui with alcohol-l'lnmed
scissors and approximately one-lhLrd of each swab vac placed in
300 ml of te1 rathionate enrichment broth, 'his v;as incubated at
J|0.5° C for iventy-i'our hours i.n a water-jacketed incubator.
Subsequently, a sterile bacteriological loop was used to streak
from the enrichment medium onto brilliant green agar plates and,
in parallel, on SEG agar plates. ' hese latter plates were aband-
oned after the first few attenpts as this method did not yield
enough presumptive 3alraonella colonies to warrant further use in
this study.
The brilliant green or the SBG agar plates were incubated
r\
at i|0.5 C overnight and characteristic presumptive Salmonella
colonies were fished with a sterile bacteriological needle and placed
in parallel on triple sugar iron (TSl) agar slant stabs, motility
sulfide (MS) agar stabs and inoculated into "H broth". Ihe TSI
slants were read between eight and eighteen hours. It was found
that leaving this medium overnight resulted in a masking of the color
reactions by excessive sulfide production, consequently shorter read-
ing intervals were used. After noting slant, butt and sulfide re-
actions in the TSI tubes, a loopful of culture from the slant was
used for a slide agglutination test with polyvalent Salmonella "0"
antiserum.
In the motility and sulfide medium, reaction for motility and
-------
sulfide was first noted, then the tubes flooded with buffered urea
solution, incubated at 35° C for six hours to note the presence or
absence of urease production. A portion of the culture in "H broth"
was used to test for the presence or absence of indol. A further
aliquot of "H broth" was used for a tube agglutination test with
polyvalent S- Imonella "H" antiserum,
Arter initially screening all cultures with this procedure,
cultures were again purified on brilliant green agar and again sub-
jected to this series of tests. Forty-one selected cultures isolated
from the upper Potomac Estuary were sent to the U.S. Public Health
Service Communicable Disease Center at Atlanta, Georgia, for further
diagnosis to species serologically.
Details of the Salmonella isolation scheme are elaborated
by Spino ^ 1 ~. Strict adherence to details outlined by Spino is
recommended, for this scheme is extremely empirical and small devia-
tions can result in failure.
-------
CLIMATOLOGICAL CONDITIONS
During 'lie months of Jnnuary and February 1967; the weather
vas generally cold and dry with the .otomac River discharge at
approximately 10,000 cfs. A light rainstorm with above-freezing
temperatures covered much of the rbtomac watershed during the
period from March h through J. The rainstorm and thaw increased
the runoff to a maximum discharge of 1^0,000 cfs on March 9, 19&7
(See Figure 2)
rhe average climatological conditions for the three months
of the study are given "below.
Parameter January February March
Air temperature (Deg. F°) ' 4l.O 34.0 1+5.0
>,r-ter temperature (Deg. F°) 37.0 37.8 42.7
R-'ver discharge (cfs) 9,700 10,800 35,600
Precipitation (inches) 1.35 2.32 3.^9
-------
$ si
a:
i
3
o
o:
o
(VI
\
0
1
r-
-------
10
RESunrs OF
Sources of . '.ilil'orm i.'
Ihree major sources of coliform organisms in the upper
estuary were: (l) wastewater discharges, (2) storm and combined
severs, and (3) fresh water inflows. Using the data for the sewage
treatment effluents for the major discharges and fresh water inflow,
an estimate of the coliform organism loadings for the months of
February 196?^ was determined and is presented below.
Coliform
(MHt/day)
0.12 x 1015
160.0 x 1015
Fecal
Coliform
(MPN/day)
15
0.04 x 10
IS
19.S x 10 '
Fecal
Strep.
(MPR/day)
0.08 x 101
60.3 x 10ll{
Fresh water inflow*
Wastewater treatment-
discharge**
As can be seen in the above tabulation, the contribution of coliform
organisms from wastewater effluents is more than 100-fold greater
than from the fresh water inflow from the upper basin. No estimate
was made of storm or combined sewer contributions.
-x Based on an average flow for the month of February 1967 of 10,800 cfs,
** Based on the bacterial densities for Blue Plains, Arlington and
Alexandria data as presented in 7 ble 2.
-------
1.1
JButuarine urter Duality Conditions
Figure 3 ic an isopleth plot* of coilform disiribution
In the study area. ! he region of greatest coliforn, density
(> 100,,000 MM/100 ml), vrith steady flow conditions of approximately
10,000 cfs, seemed to equilibrate in the reach from just below the
District of Columbia downstream to Hallowing Point, approximately
15 miles of estuary, "'he sudden rise in fresh water flows carried
these high colifom densities, vilh some snail contribution from
local land runoff as evidenced by the increased count at Chain Bridge,
downstream at least 40 miles, the lower limit of this study.
rl:is investigation did not include the estuary below ;iathias
ioint which is the upper limit of the oyster harvesting areas. " hese
waters would probably be affected by the increased flows which trans-
port the indicator organisns apparently originating in the metropoli-
tan area.
rrhe fecal coliform densities (Figure k) showed a similar
response to the high flow conditions, but at a bacterial density
approximately one decimal order of magnitude lower than coliforms.
rhe reach of the estuary affected was identical.
Figure 5 presents the distribution of fecal streptococci in
the upper iv;tonac Estuary. Distribution patterns were similar to
* An isopleth is made by plotting coliform densities as a function of
time and distance, and connecting equal values. Vhe response of the
estuary to the coliforrr, loadings can be seen at a given time by follow-
ing distributions from a fixed point in time down the horizontal axis,
representing the roach of estuary studied. Conversely, at a fixed
point in the estuary, the changes of the densities with time can be
seen by reading up a vertical axis from a designated location.
-------
12
those for conforms and fecal conforms, but the area of high
'bacterial density uas not as extensive, consonant v;ith the concept
\.hat fecal streptococci have a relatively faster die-off rate in
'.rater than coliforns or fecal eolifoms and are indicators of recent
pollution. ' 3 i
F'gure 6 shows the exposure of Salmonella swabs and subsequent
recovery or lack of recovery of .'.alnonella isolates. r he area of
greatest incidence included the netropontan area downstream to
.Indian head, Maryland. Somewhat surprising were the isolations from
Jhain Bridge, where generally1- lo\\' colifom and fecal coliform densi-
ties v/ere found.
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DISCUSSION
Indicator Bacteria In the 1 o:iac Estuary
' ]'.e ll-fold 'ncrease in fresh water flow of the -tonac
-ver during 1 he cl udy sllghj ly Increased the oacterJal densities
cf colli'ornG, fecal eolif orris and fecal streptococci coning into
1 ho o^luur;' fro,: he upper basin, ".'.esc came "low conditions,
however, dramatically decreased 'he relatively,' large "bacterial
populations found in "! he metropolitan reach between the confluence
wJ-th the Anacosiia RLvcr dovn 1 o Halloain^ oint, apparently by
flushing and diluting action, '.'he lover reaches of the estuary, at
least to the downstream limit of this study, vere contaminated by
this excursion.
Using a fecal coliforr. standard of 2^0 MPN/100 nl for water
contact recreation, the Potomac Satuary from Chain Bridge to Indian
head would be unacceptable, and under some conditions, for the length
of estuary investigated.
Ihe distribution of the Indicator species followed established
patterns, i.e., coliforms most prevalent, fecal coliforms approximately
a decimal order of magnitude la/er, and a much more restricted distri-
bution of fecal streptococci. nhe lesser numbers of the latter two
are probably due in part to a lack of aftergrowth as suggested by
Evan, et al L 3 _,.
-------
;jjne experimenial findings by other investigators indicate
there may be a significance in the fecal coliform/fecal streptococci
ratio (FC/F3). Geldreich ~" u postulated ihat a ratio of lees
-han 0.7 indicates animal pollution and/or urban stornwater discharges
wljh higher ratios oreGumaDly due to human sources.
Examination of the FC/FS ratios as presented in '"able 3
indicates: (j ) a much wider flucl nation of ratios in the river than
in the sewage treatment plants, (2) the magnitude of the ratios in
the three treatment plants tended to fluctuate together, indicating
a common cause such as infiltration, and (~) a dramatic general
decrease in 1 he .Tagnitude of the ratio in the estuary after March 5,
vhen the river flows rose. ' he interpretation of the fluctuations in
1 he treatment plant data is confounded in that the precipitation was
in the form of snow, with thawing temperatures during the days and
freezing at night. Runoff patterns as well as Infiltration rates
Into sevage systems are difficult to establish under these conditions.
rjlie data, assuming the FC/FS ratio is valid, indicate the
major source of pollution was from human sources in the estuary during
the period from February 15 through :.arch 5, 1967. Even with a l^-fold
dilution effect, as the result of the increased runoff, the ratio still
indicates the source to be substantially of human origin.
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Distribution of Salmonellae
Salmonellae were recovered from areas of the _'tomac
Actuary with chronically/ high coliforn, fecal col." form and fecal
si reptococci, Taut not from areas where these bacterial densities
were generally at acceptable levels under 1 he environmental condi-
tions during this sjudy.
"he Salmonella data cannot l-e compared vith the indicator
bacteria on a sound statistical basis because of their paucity and
their non-"oararietr:'. c nature. Ii Lz instructive, however, to compare
the percent of J. iraes Gelrr.onellae vere recovered with the densities
of indicator organisms. Figure 7 shows the relationships found.
At coliform densities less than ^00 "FK, 100 ml, fecal coliforms at
100 MFN/100 ml, and fecal streptococci at 20 MHi/100 ml, no Salmon-
ellae were recovered. ' he greater incidence of Salmonella recovery
vas generally at higher indicator bacteria densities.
The incidence of Calmonellae in the ;'otomac Ectuary confiriis
the usefulness of coliforas and fecal coliforms as indicators of
bacterial pollution, '/oreover, the high incidence of Jalmonellae in
waters with high bacterial densities of coliforms and fecal coliforras
nake the numerical indices used in water quality standards more
realistic. rhis is contrary to some studies on fresh water rivers as
reported by Gsllagher and Gpino [ k ].
All of the isolates sent to the "J.£. Public Health Service
Communicable D:sease Onter for sero-tyning proved to be Salmonella
-------
species. ; apparent- relatior_sh"-.T>c existed between the species of
, t'l'.ionella and "I he d i 3"! rit>u"! 'on :''~ 'he est.iary, bu"1 4 he data are
i tUJu.iT; f.' L'"Mt i r) d-'vn1 r.ourid C'lrir.l"..'' T.^.
-------
157
I I 32
INDICATOR-BACTERIAL DENSITY
and
SALMONELLA RECOVERY
UPPER POTOMAC ESTUARY
FEBRUARY-MARCH 1967
CHESAPEAKE TECHNICAL SUPPORT LABORATORY
100.000
£85,960
AS6.520
21,945
10.000
A 4.840
11.920
A 6.652
A 1.447
o
o
a
in
5
o
ae
O
12,520
1,000
100
M27
'III
726
A 800
384
169
121
I 1.991
i.on
1316
I ISO
A|« 16
10
KEY
A COLIFORMS
FECAL COLIFORMS
FECAL STREPTOCOCCI
30 40 50 60
PERCENT SALMONELLA RECOVERY
FIGURE 7
-------
SUMMARY
'J he findings of the sanitary bacteriological survey of the
upper ^toraac Estuary during January-March of 1967* are summarized
below:
1. i'igh colifom, fecal coliform and fecal streptococci
densities were found in the ,,V'Shington metropolitan area.
2. A potential health hazard existed in the ,-^shington
.net ropolil an area, wi'h .- - InoneHa organisms readily and regularly
isolated.
3- ""i-ree of the four major sewage treatment plants in the
,,'r'Shington metropolitan area conl ributed large volumes of indicator
bacteria as well ac r f;lirionellae, to the upper I'otonac Estuary.
h. -A rapid rise in river floirs during the study had a
two-fold effect on water quality by (a) considerably reducing by
dilution the bacterial densities in the upper estuary near the waste-
water discharges, and (b) increasing the bacterial densities in the
middle estuary by flushing indica^ or organisms downstream a distance
of at leasi 50 miles.
5. Fecal coliform/fecal streptococci ratios indicated that
the bacterial pollution in the upper "toraac Estuary was probably of
human origin.
6. I'i gcneral, greater incidence of Jalraonella recovery was
oblained In waters having high indicator-bacterial densities.
-------
BIBLIOGRAPHY
1. ,".pino, ''-I1'., ''Sleva! eel ' frrperature ' ^chn:l;me for the Isolation
of oalnonella from .3'rears", Applied. Microbiology I'l: 591-596, 1966
'°* -'taridarcl M'-i,hcxic roi-i ho M'ca-nJnation or -''ter and ',';'Gtewater,
12th ed., APHA, 1965
'. Evans, F.I,., GeldreJch, /..E., '/clbel, C.R. ?>, K'.beoh, G.G.,
"Treatnent of Urban ,"torri5.'ater Funoff", J. ','^ter Pollution Control
Federation ^0: ia62-170, 1968
k. Gallagher, '_ . P. and ,'jpino, D.F., "'.he Significance of jucibers of
Coliform Bacteria as an Indicator of Enteric Pathogens", Water
Research, 2:169-17$, 1968
,c;. Geldreich, S.S. ,"Sanitary Significance of 7ecal Coliforms in the
Environnent", U.S. Department of the Interior, jWPCA Publication
WP-20-3, 122 pp., 1966
6. Geldreich, 2.E., "Fecal C-liform Concepts in Ctrean Pollution",
'./ater and Sewage ,,'orks, Reference Ilnnber, 1967
-------
Chesapeake Technical Support Laboratory
Middle Atlantic Region
Federal Water Pollution Control Administration
U.S. Department of the Interior
Technical Report No.
THE POTOMAC ESTUARY
MATHEMATICAL MODEL
by
Leo J. Hetling*
(Special Consultant)
March 1969
In cooperation with the staff of:
Chesapeake Technical Support Laboratory
Johan A. Aalto
Norbert A. Jaworski
Donald W. Lear, Jr.
Dr. Hetling was formerly the Deputy Director of the Chesapeake
Field Station, U.S. Department of the Interior, Federal Water
Pollution Control Administration, Middle Atlantic Region,
Annapo 1 is, Ma ryland
-------
TABLE OF CONTENTS
Page
INTRODUCTION 1
THE MODEL 2
MODEL VERIFICATION USING DYE STUDIES
WATER QUALITY MODELING RESULTS 11
Chlorides 11
Dissolved Oxygen 14
USES OF THE POTOMAC ESTUARY MODEL 17
REFERENCES 19
-------
LIST OF FIGURES
Nujnoer page
I Potomac Fiver Study Area 4
2 Factor A: fecting .Siream Dissolved
Oxygen Concentration 7
3 Potomac Estuary, Observed and Calculated
Dye Concentration Versus Time 10
A Potomac Estuary Cnioride Model, 1965
Chlorides at Possum Point 12
5 Dispersion Coefficient Versus Distance
From Cr.ain Bridge 13
t Potomac Estuary, 19c5 District of Columbia
Data, DO, Memorial Pridge 15
; Potomac Estuary, I^o5 District of Columbia
Data, DO, Woodrow Wilson Memorial Bridge , . 16
-------
INTRODUCTION
A systems analysis approach nas beer, undertaken by the
Federal #nter iollution Control Aibniniftrntion (FWPCA) in
; nvet; t. i^at ing the water quality responses in the Potomac
River Basin [ 1 ]. The analyses included the effects of
low flow augmentation, wasteweter diversions, water supply
withdrawals, and increased degrees of wastewater treatment
on water Duality in tne upper estuary.
oeveral techniques or raathemBtical models* capable of
simulating the response of water quality in an estuary
were avajlable when the study of the Potomac Estuary was
undertaken in I'O. After sj. investigation of the modeling
systems available, the segmented estuary model developed
by Dr. Robert Tho/nann [ 2 ] was selected as the one which
most closely conformed to the reouirements of the study.
The segmented model is hignly flexible and capable of
being utilized to describe almost any pollutant. Its accu-
racy is adequate foi engineering aesign purposes. Properly
programmed, the digital computer makes possible solutions
of the systems available in minutes at a relatively small
cost.
* A key element in any systems study ia a model capable of
describing or simulating the system of interest.
-------
THE MODEL
li; order to give the non-engineers among you sane idea
of wh«t n mathematical mod^l i.-., i would i ik^ to quote from
a description ol" models i previously prepared [ > \:
"Anyone who nas a cheeking account works with a rnathe-
natical model. All deposits are positives and all
withdrawals are negatives. Monthly service charges and
a charge per check further completes the model. Using
technical jargon, we con say that the model has a lower
limit (or bound - using the correct mathematical term)
in that a negative balance cannot, ir. theory, exist.
With a knowledge of all the inputs (deposits and with-
drawals), the initial conditions (original balance) and
other sources and sines (service charges), it is possible
to compute the balance at any time (a transient model).
"In the same way, by proper bookkeeping and a knowledge
of bounds or limits, inputs, initial condition, sources
and sinks, it is possible to develop a act of equations
which describe water quality in the estuary. The number
of computations, of course, in this system when compared
with a checking account is enormous. To solve such a
system would require many man-years. But, luckily,
most of the computations are routine addition, subtrac-
tion, and multiplication. Within recent years, digital
-------
computers have been developed which can do such routine
corapxi tat ions in a fraction of a second. Properly
instructed (prosrammed), the digital computer makes
possible solutions of the system available in minutes.
"A key step in the development of any model is its
verification; i.e., to check and see if the model truly
simulates water quality. This involves a comparison
of measured or ooservec values with computed values.
"A checking account is verified every so often when a
statement is received from the bank. When we compare
the balance in our checkbook with the balance on the
bank statement, we find time after time that we have
made a mistake. More often than not, it is a blunder;
an input (deposit or withdrawal) was forgotten, the
bank service charge was changed, or perhaps even the
bank made a mistake."
In a more technical sense, the mathematical model for
the Potomac Estuary was constructed by dividing the estuary
into a finite number of discrete segments as shown in
Figure 1. The segment* were nade small (approximately two
miles in length) near the critical portion of the estuary
where the rate of changes of water quality is greater and
longer in the lower sections where there are small changes
-------
V
y
- < 10,-
- -'?
. as. .fGM£NT
/_ o AGING CATION
i.^^ POTOMAC S'V'S at //AiHINGTC'N. fl
A t «AfJOW'A SAM'ABv AU ' MOd I V
:A(,;A- -., IIM - / wfs'&ATt I^A
TAiROvi ll^i* . 'T'LE
18
:\ MILLS
~r ~~- r~?7-
POTOMAC RIVEF- STUDV
-------
in water quality. The assumption is made that the water
quality in each segment :^ Homogeneous if the segments are
properly selected, anct n' x.ney are made small enough, this
is a proper assumption.
For each water quality parameter we started by writing
uie equations utilizing all the factors which we felt would
affect ;,he giver water quality parameter. The upper Potomac
Estuary model for a non-conservative pollutant such as a
Diocheinical oxygen demand *,BOD) consists of a system of 21
equations, each describing & mass BOD balance for the 21
segments of the estuary.
The mass oalance over each of the 21 segments shown in
Figure 1 includes terse describing changes in BOD concen-
tration caused by advection, dispersion, decay, and BOD
added by the various sources. Trie system of 21 linetr
first order, non-homogeneous, ordinary differential equations
which describes the changes Is then solved simultaneously by
numerical methods using a digital computer.
Dissolved oxygen (DO) is probably one of the cost impor-
tant parameters to joiow when talking about the water quality
of the estuary. It is aleo t,he moet difficult to model,
since DO can enter or leave the estuary in so many different
ways. Figure 2 will give you an idee of the system which
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affects DO concentration _;; an estuary. Factors such as
bent hie uptake of oxygen, r,i truncation, and photosynthesis
further complicate the DO nalanop ;n the Potomac Estuary.
For simulating tne DU :. the upper estuary, the model
consists of 4^ equations, ,;I describing a mass balance for
the ultimate oxygen aemar.d (UODj and ^1 equations for the
Dissolved oxygen. Vertica. and lateral noroegeneity in
each segment are aasuaed.
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MODEL VERIFICATION USING DYE STUDIES
I wouici iiKe to describe a iarge-eeale study which was
carne. , I '^ , trify the ;nodel .n order to give you a
better feel for its capabilities [ 4 j.
Most natural water quality parameters are involved in
so man.\ Cample* chemical, Biochemical, and physical reactions
that they do not lend theaselves to a good simple test of
the moael. Therefore, our first attempt at verification was
a dye diffusion study. We injected a semi-conservative dye
(Rhodaoine WT) into the estuary through the effluent pipes
of the District of Columbia's Water Pollution Control Plant
at a known rate. See Figure 1 for the location of the waste-
water treatment plant.
Figure 3 shows the resulting average dye concentration
in the estuary inaasured opposite the plant outfall. The
solid center line shows the concentration of dye predicted
by the model, while the other two lines represent the actual
measured concentratxons at high and low tide.
The matching of the observed data and calculated data
did not, of course, occur on our first try with the initial
model coefficients. Many repetitive runs of the model were
required to get the match you see here. For each repetitive
run, a change in a coefficient was made in order to bring
the predictive concentrations closer to the measured values.
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The close agreement betirecn the measured and calculated
dye concentrations found in the above study shows that the
segmented estuary model can satisfactorily describe water
quality which will result from the introduction of a simple
soluble pollutant into the estuary if the correct coeffici-
ents are known.
In contrast to the thinking of many people, mathesiatical
models no not relieve the engineer fron making assumptions
and decisions; what it does do is force him to test the
validity of these assumptions by coaparing their compatibility
with actual measured results.
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