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,

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                           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.

-------
                              DISSOLVED  OXYGEN     ISOPLETH
                                             Ug/l)
                                   UPPER  POTOMAC ESTUARY
                                      MAr I-, C\. T.J8ER 1968
                               CHISAPEAKF  TECHNICS SUPPORT LABORATORY
'  j
                                                                                         FiGURE 11-3

-------
                                                                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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-------
                               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-
                                                                    \  ^  • >

 estuary is  the  annual  variation in nutrient contribution by the    ^  - ov
                                                                    ,.  o  *•
 sources.   The average  monthly loadings from the wastewater  discharges


 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.

-------

-------
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-------
                                                             11-12








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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.  No—Nitrogen
                                     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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                                                                                         |

                                                                                         UJ
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-------
 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
 Q.
 O
 cx
 O
 _j
 I
 O

 -o
 c
 o

1/1
I-
Z

 ul

 O
 o
 a
                  O


                  4
O
a
a
     «M     w
cq     •*
d     o
                                                                                                                        O
                                                                                                                        O
                                                                                                                        
-------
jo  iooj
                            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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a:
8
       z
       Ul
       t-
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2  S  o
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                                                              u.
                                                              z d
                                                                3
                                                              I*
                                                                2*
                                                                a.
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                                                                             J


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                                                                             z
                                                                             Ul
                                                                             U

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                                          b
                                          
-------
IT)


Q

fe
cr
K
2
UJ

2
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U
     


I2!
Z    z
_J
8
3

u
                     j§


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                     2
                     UJ

                     8
                     ac.


                     2
                                                           (O O
             O

             O
             rvj
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00
                                                 O
                                                      FIGURE III-6

-------
                                                                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.

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                                                                 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

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                           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

-------
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-------
                                                                  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 _,.

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        ;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.^.

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        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
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a
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5
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                                                                             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

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                               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.

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                            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

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               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

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                      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

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                          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

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                       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.

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                       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

-------
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.

-------
    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.

-------