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TIDEWATER ADMINISTRATION MARrLAND DEPARTMENT 0F
NATURAL RESOURCES
-------
INTENSIVE WATERSHED STUDY
THE PATUXENT RIVER BASIN
by
Charles Bostater
Diane McCraney
Stephanie Berlett
David Pushkar
Maryland Department of Natural Resources
Annapolis, Maryland 21401
Grant No. R80636
Project Officer
James Smullen
EPA Chesapeake Bay Program
2083 West Street, Suite 5G
Annapolis, Maryland 21401
Environmental Research Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
Gulf Breeze, Florida
-------
DISCLAIMER
This report has been reviewed by the U.S. Environmental Protection
Agency, and the Maryland Department of Natural Resources, and approved
for publication. Approval does not signify that the contents necessar-
ily reflect the views and policies of the U.S. Environmental Protection
or the Maryland Department of Natural Resources, nor does mention of
trade names or commercial products constitute endorsement or recommen-
dation for use.
-------
FOREWORD
iii
-------
ABSTRACT
This study was one of five intensive watershed studies designed to
provide detailed non-point source loading rates and ambient water quality
data within the Chesapeake Bay drainage area.
The study consisted estuarine slack tide surveys, intensive
twenty-four hour water quality surveys, primary productivity measurements,
sediment oxygen demand and sediment nutrient flux measurements,
phytoplankton and nitrifying bacterial longitudinal surveys, non-point
source monitoring at five subwatersheds current speed and direction
measurements as well as rainfall quality and quantity measurements.
This report was submitted as partial fulfillment of the Maryland
Department of Natural Resources grant No. R806306010 under sponsorship of
the U.S. Environmental Protection Agency, Chesapeake Bay Program.
iv
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CONTENTS
Foreward iii
Abstract iv
Figures vi
Tables " xxii
Abbreviations and Symbols xxxi
Acknowledgements xxxii
Section
1. Introduction, Executive Summary, Conclusions,
Recommendations 1
2. Methods 7
3. Land Utilization, Population, and Wastewater Projections. .23
4. Physical Characteristics of the Patuxent River 25
5. Sources of Nitrogen and Phosphorus to the Patuxent River. .30
6. Non-Point Source and Meteorological Watershed Monitoring. -33
7. Description of Longitudinal Slack Survey Results 40
8. Temporal Variation of Water Quality Variables 47
9. Intensive Water Quality Survey Variable Results 54
10. Historical Perspective of Dissolved Oxygen and Deficits . .60
11. Results and Discussion 67
References 88
Appendices
A. Figures and Tables for Methods; Section 2 94
B. Figures and Tables for Section 3. ...... . 129
C. Figures Presenting Physical Characteristics; Section 4. . 135
D. Box Models; Section 5 151
E. Statistical Analyses of Non-Point Sources; Section 6. . . 158
F. Longitudinal Slack Survey Figures and Tables; Section 7 . 215
G. Temporal Water Quality Figures and Tables; Section 8. . . 335
H. Intensive 24-Hour Survey Figures and Tables; Section 9. . 439
I. Figures and Tables of Dissolved Oxygen Characteristics;
Section 10 634
J. Figures and Tables for Section 11 793
K. Intensive Watershed Study: Non-Point Source Watershed
Logbook
v
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FIGURES
Number Page
2-1 Map of Intensive and Slack Water Sampling Stations 8
2-2 Map of Slack and Lateral Slack Water Sampling Stations ... 9
2-3 Map of University of Maryland Lower Estuary Water
Quality Stations 123
2-4 Map of Biospherics Biological and Benthic Stations 124
2-5 Map of University of Maryland Benthic Oxygen Demand and
Nutrient Flux Stations 125
2-6 Diagram of Sediment Oxygen Demand Chamber 126
2-7 Non-Point Source Watershed Sample Collection and Analysis
Scheme 128
3-1 Patuxent River Historical Land Utilization 130
3-2 Historical Population Projections 131
3-3 Current Population Projections 132
4-1 Drainage Area and Cumulative Drainage Area Plot 136
4-2 Crossectional Area and Cumulative Crossectional Area Plot . . 137
4-3 River Width and Cumulative Width Plot 138
4-4 Volumes and Cumulative Volume Plot 139
4-5 Surface Area and Cumulative Surface Area Plot 140
4-6 Hydraulic Depth and Cumulative Hydraulic Depth Plot 141
4-7 1980-1981 Freshwater Inflow at Route 50 142
4-8 Historical Mean Monthly Flow Comparison at Route 50 143
4-9 Schematic Diagram of Flow in the Patuxent Estuary 144
4-10 Patuxent Estuary Velocity Profiles 145
VI
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FIGURES (continued)
Number Page
4-11 Patuxent Estuary Velocity Profiles 146 .
4-12 Location of Current Meeter Moorings 147
4-13 Observed and Estimated Salinity Function 148
4-14 Estimated Fraction of Freshwater and Chesapeake Bay
Water 149
4-15 Estimated Flushing Time in the Patuxent Estuary 150
5-1 Patuxent River Total Nitrogen Budget 153
5-2 Patuxent River Dissolved Nitrite Plus Nitrate Budget.. 154
5-3 Patuxent River Dissolved Ammonia Budget 155
5-4 Patuxent River Total Phosphoros Budget 156
5-5 Patuxent River Dissolved Orthophosphoros Budget 157
/
6-1 Map of 5 Watersheds Monitored For Chemical Export 159
6-2 Map of Soil Groups for G-farm and Z-farm Site 161
6-3 Deale A and Deale B Watershed Land Utilization 163
vii
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FIGURES (continued)
Number Page
7-1 Slack Tide Salinity Profiles for 1980 216
7-2 Slack Tide Salinity Profiles for 1981 217
7-3 Longitudinal Slack Survey Plots for Salinity 218
7-4 Longitudinal Slack Survey Plots for Temperature 223
7-5 Longitudinal Slack Survey Plots for pH 228
7-6 Longitudinal Slack Survey Plots for Seechi Disc 233
7-7 Longitudinal Slack Survey Plots for Dissolved Oxygen . . 238
7-8 Longitudinal Slack Survey Plots for Dissolved Oxygen
Saturation 242
7-9 Longitudinal Slack Survey Plots for Dissolved Nitrate . . 247
7-10 Longitudinal Slack Survey Plots for Dissolved Nitrite . . 252
7-11 Longitudinal Slack Survey Plots for Dissolved Ammonia . . 257
7-12 Longitudinal Slack Survey Plots for Total Particulate
Nitrogen 262
7-13 Longitudinal Slack Survey Plots for Total Kjeldahl
Nitrogen . . 267
7-14 Longitudinal Slack Survey Plots for Dissolved Organic
Nitrogen 272
7-15 Longitudinal Slack Survey Plots for Total Organic
Carbon 277
7-16 Longitudinal Slack Survey Plots for Total Phosphorus . . 279
7-17 Longitudinal Slack Survey Plots for Total Particulate
Phosphorus 284
7-18 Longitudinal Slack Survey Plots for Dissolved
Phosphorus 289
7-19 Longitudinal Slack Survey Plots for Dissolved
Ortho-Phosphorus 294
vi i i
-------
FIGURES (continued)
Number page
7-20 Longitudinal Slack Survey Plots For Total N:P Ratios . . 299
7-21 Longitudinal Slack Survey Plots for Dissolved N;P
Ratios 302
7-22 Longitudinal Slack Survey Plots for B0D5 305
7-23 Longitudinal Slack Survey Plots for Chemical Oxygen
Demand 310
7-24 Longitudinal Slack Survey Plots for Chlorophyll-a . . . 312
7-25 Longitudinal Slack Survey Plots for Pheophytin-a .... 315
\
7-26 Longitudinal Slack Survey Plots for Silica 320
7-27 Longitudinal Slack Survey Plots for Total Nonfilterable
Residue 325
8-1 Temporal plots of Salinity 336
8-2 Temporal Plots of Temperature 340
8-3 Temporal Plots of pH 345
8-4 Temporal plots of Seechi Disc 350
8-5 Temporal Plots of Dissolved Oxygen 355
8-6 Temporal Plots of Dissolved Oxygen Saturation 360
8-7 Temporal Plots of Dissolved Nitrite 365
8-8 Temporal Plots of Dissolved Nitrate 370
8-9 Temporal Plots of Dissolved Ammonia 375
8-10 Temporal Plots of Total Organic Nitrogen 380
8-11 Temporal Plots of Total Particulate Nitrogen 385
8-12 Temporal Plots of Total Phosphorus 390
8-13 Temporal Plots of Dissolved Phosphorus 395
8-14 Temporal Plots of Dissolved Ortho-Phosphorus 400
IX
-------
FIGURES (continued)
Number Page
8-15 Temporal Plots of Total Particulate Phosphorus 405
8-16 Temporal Plots of Dissolved Organic Carbon 410
8-17 Temporal Plots of Pheophytin-a 415
8-18 Temporal Plots of Silica 420
8-19 Temporal Plots of Total Nonfilterable Residue 425
8-20 Temporal Plots of B0D5 430
9-1' Intensive River Survey Plots of Salinity 440
9-2 Intensive River Survey Plots of Temperature 448
9-3 Intensive River Survey Plots of pH 458
9-4 Intensive River Survey Plots of Dissolved Oxygen 468
9-5 Intensive River Survey Plots of Dissolved Oxygen
Saturation 478
9-6 Intensive River Survey Plots of Seechi Disc 488
9-7 Intensive River Survey Plots of Dissolved Nitrate .... 498
9-8 Intensive River Survey Plots of Dissolved Nitrite .... 508
9-9 Intensive River Survey Plots of Dissolved Ammonia .... 518
9-10 Intensive River Survey Plots of Total Organic Nitrogen . . 528
9-11 Intensive River Survey Plots of Total Particulate Nitrogen 538
9-12 Intensive River Survey Plots of Total Phosphorus 548
9-13 Intensive River Survey Plots of Total Particulate Ph
Phosphorus 558
9-14 Intensive River Survey Plots of Dissolved Phosphorus . . . 568
9-15 Intensive River Survey Plots of Dissolved Ortho-Phosphorus 578
9-16 Intensive River Survey Plots of Silica 588
x
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Page
595
605
615
631
632
639
640
640
639
643
643
644
652
653
654
655
656
FIGURES (continued)
Intensive River Survey Plots of Pheophytin-a
Intensive River Survey Plots of Total Nonfilterable
Residue
Intensive River Survey Plots of B0D5
Intensive River Survey Plots of Stage Height
Intensive River Survey Plots of Current Velocity
Historical Yearly Mean Dissolved Oxygen in the Patuxent
Estuary
Historical Yearly Mean Dissolved Oxygen in the Lower
Patuxent Estuary
Historical Yearly Mean Dissolved Oxygen in the Upper
Patuxent Estuary
Historical Yearly Mean Dissolved Oxygen for the Month
August in the Upper Patuxent River
Historical Yearly Mean Dissolved Oxygen For the Month
August in the Upper Patuxent River
Historical Yearly Mean Dissolved Oxygen for the Month
August in the Lower Patuxent Estuary
Patuxent River Plots of Historical Dissolved Oxygen Versus
Salinity, 1936—1981
Map of Patuxent River Segments for Historical Dissolved
Oxygen Seasonal Trend
Patuxent River Plot of Historical Seasonal Dissolved
Oxygen, Segment One
Patuxent River Plot of Historical Seasonal Dissolved
Oxygen, Segment Two
Patuxent River Plot of Historical Seasonal Dissolved
Oxygen, Segment Three . .
Patuxent River Plot of Historical Seasonal Dissolved
Oxygen, Segment Four
XI
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FIGURES (continued)
Number Page
10-13 Patuxent River Plot of Historical Seasonal Dissolved
Oxygen, Segment Five 657
10-14 Patuxent River Plot of Historical Seasonal Dissolved
Oxygen, Segment Six 658
10-15 Patuxent River Plot of Historical Seasonal Dissolved
Oxygen, Segment Seven 659
10-16 Patuxent River Plot of Historical Seasonal Dissolved
Oxygen, Segment Eight 660
10-17 Patuxent River Plot of Historical Seasonal Dissolved
Oxygen, Segment Nine 661
10-18 Patuxent River Plot of Historical Seasonal Dissolved
Oxygen, Segment Ten 662
10-19 Patuxent River Plot of Historical Seasonal Dissolved
Oxygen, Segment Eleven 663
10-20 Patuxent River Plot of Historical Seasonal Dissolved
Oxygen, Segment Twelve 664
10-21 Patuxent River Plot of Historical Seasonal Dissolved
Oxygen, Segment Thirteen 665
10-22 Patuxent River Plot of Historical Seasonal Dissolved
Oxygen, Segment Fourteen 666
10-23 Patuxent River Plot of Historical Seasonal Dissolved
Oxygen, Segment Fifteen 667
10-24 Patuxent River Plot of Historical Seasonal Dissolved
Oxygen, Segment Sixteen 668
10-25 Patuxent River Plot of Historical Seasonal Dissolved
Oxygen, Segment Seventeen 669
10-26 Patuxent River Plot of Historical Seasonal Dissolved
Oxygen, Segment Eighteen 670
10-27 Patuxent River Plot of Historical Seasonal Dissolved
Oxygen, Segment Nineteen 671
Xii
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FIGURES (continued)
Number Page
10-28 Patuxent River Plot of Historical Seasonal Dissolved
Oxygen, Segment Twenty 672
10-29 Patuxent River Dissolved Oxygen Deficits at Various Depth
Ranges 673
10-30 Patuxent Estuary Historical Dissolved Oxygen Deficits
(0.0 to 21 ppt) 674
10-31 Patuxent Estuary Historical Dissolved Oxygen Deficits
(2.0 to 21 ppt) 675
10-32 Patuxent Estuary Historical Dissolved Oxygen Deficits
(10.01 to 21 ppt) 676
10-33 Monthly Average Dissolved Oxygen Deficits in the Patuxent
River 711
10-34 Patuxent River Plots of Historical DOD vs Salinity 1936-
1981 782
10-35 Patuxent River Cumulative Frequency Distribution for All
Historical Data, 1939-40 Data and 1980-81 Data 790
10-36 Cumulative Frequency Distribution of All Historical DOD in
the Upper and Lower Patuxent River 791
10-37 Cumulative Frequency Distribution of DOD for Historical
Data, Current Data and Salinity Regimes (0.2 - 10 ppt
and greater than 10 ppt) 792
11-1 Patuxent River Longitudinal Characterization of 1980-1981
Data for B0D5 (mg/1), Alkalinity (mg/1), and pH 794
11-2 Patuxent River Longitudinal Characterization of 1980-1981
Data for Pheophytin-a (mg/1), Total Nitrogen (mg/1)
and Salinity (ppt) 795
11-3 Patuxent River Longitudinal Characterization of 1980-1981
Data for Chlorophyll-a (mg/1), Dissolved Reactive
Silica (mg/1) and Corrected Chlorophyll-a (mg/1) 796
11-4 Patuxent River Longitudinal Characterization of 1980-1981
Data for Temperature (°C), Dissolved Oxygen (mg/1)
and Total Nonfilterable Residue (mg/1) 797
11-5 Patuxent River Longitudinal Characterization of 1980-1981
Data for Dissolved Nitrite (mg/1), Dissolved Ammonia
(mg/1) and Chlorides (mg/1) 798
xiii
-------
FIGURES (continued)
Number Page
11-6 Patuxent River Longitudinal Characterization of 1980-1981
Data for Dissolved Ortho-Phosphorus (mg/1), Dissolved
Phosphorus (mg/1) and Total Organic Carbon (mg/1) .... 799
11-7 Patuxent River Longitudinal Characterization of 1980-1981
Data for Total Phosphorus (mg/1), Dissolved Nitrate
(mg/1) and Total Dissolved Nitrogen (mg/1) 800
11-8 Patuxent River Longitudinal Characterization of 1980-1981
Data for Dissolved Oxygen Saturation (%) and Dissolved
Organic Carbon (mg/1) 801
11-9 Correlation Coefficient (log of total N:P ratio versus
nautical mile) Plotted Against the Log of the
Beginning and Ending Antecedant Storm Days for the
Patuxent Estuary 802
11-10 Correlation Coefficient (log of total N:P ratio versus
nautical mile) Plotted Against the Log of the Middle
Antecedant Storm Days for the Patuxent Estuary 803
11-11 Cumulative Frequency Distributions of Chlorophyll-a (mg/1)
and Dissolved Oxygen (mg/1) Collected During 1980-1981
Slack Water and Intensive River Surveys 804
11-12 Cumulative Frequency Distributions of Total Nonfilterable
Residue (mg/1) and Total Kjeldahl Nitrogen (mg/1)
Collected During 1980-1981 Slack Water and
Intensive River Surveys 805
11-13 Cumulative Frequency Distributions of Pheophytin-a (mg/1)
and Dissolved Ammonia (mg/1) Collected During 1980-
1981 Slack Water and Intensive River Surveys 806
11-14 Cumulative Frequency Distributions of B0D5 (mg/1) and COD
(mg/1) Collected During 1980-1981 Slack Water and
Intensive River Surveys 807
11-15 Cumulative Frequency Distribution of Secchi Disc (meters)
and Total Particulate Phosphorus (mg/1) Collected
During 1980-1981 Slack Water and Intensive River
Surveys 808
11-16 Cumulative Frequency Distributions of Dissolved Nitrite (mg/3)
and Dissolved Nitrate (mg/1) Collected During 1980-1981
Slack Water and Intensive River Surveys 809
xiv
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FIGURES (continued)
Number Page
11-17 Cumulative Frequency Distribution of Total Organic Carbon
(mg/1) and Silica (mg/1) Collected During 1980-1981
Slack Water and Intensive River Surveys 810
11-18 Cumulative Frequency Distributions of Total Organic
Nitrogen (mg/1) and Total Particulate Nitrogen
(mg/1) Collected During 1980-1981 Slack Water
and Intensive River Surveys 811
11-19 Cumulative Frequency Distributions of Dissolved Phosphorus
(mg/1) and Total Phosphorus (mg/1) Collected During
1980-1981 Slack Water and Intensive River Surveys . . . 812
11-20 Cumulative Frequency Distribution of Temperature (°C) and
Salinity (ppt) Collected During 1980-1981 Slack Water
and Intensive River Surveys 813
11-21 Cumulative Frequency Distribution of Dissolved Ortho-
Phosphorus (mg/1) Collected During 1980-1981 Slack
Water and Intensive River Surveys 814
11-22 Lower Patuxent River Data Plot of Total Phosphorus versus
Total Particulate Phosphorus, 1980-1981 815
11-23 Plot of Particulate Carbon Versus Chlorophyll-a in the
Lower Patuxent Estuary, 1980-1981 817
11-24 Plot of Slack Water Survey Data, Log Ortho-Phosphorus
Versus Soluble NO2+NO3 for the Patuxent River,
1980-1981 818
11-25 Plot of Slack Water Log Ortho-Phosphorus Versus Total
Dissolved Inorganic Nitrogen in the Patuxent River,
1980-1981 819
11-26 Number of Species and Phytoplankton Cells Observed Along
the Lower Patuxent River During July, 1980 822
11-27 Number of Species and Phytoplankton Cells Observed Along
the Lower Patuxent River During April, 1981 825
11-28 Estimated Cells of Phytoplankton During the July 1980
Longitudinal Survey 826
11-29 Dominant Classes of Phytoplankton Observed During the
July 1980 Longitudinal Survey 827
xv
-------
FIGURES (continued)
Number Page
11-30 Dominant Classes of Phytoplankton Observed During the April
1981 Longitudinal Survey 828
11-31 Estimated Longitudinal Profile of Diatoms and the Green
Algae (tentatively identified as Nannochloris) During
the Patuxent River April 1981 Survey 829
11-32 Comparison of Diatom Cell Count in the Patuxent River April
1981 Survey 830
11-33 Diatom Cell Count in the Patuxent River July 1980 Survey ¦ 831
11-34 Relationship Between Mean Total Phosphorus, Mean Dissolved
Nitrate and Mean Salinity at Mainstem Patuxent Estuary
Stations, 1980-1981 846
11-35 Relationship Between Mean Dissolved Phosphorus, Mean Silica
and Mean Salinity at Mainstem Patuxent Estuary Stations,
1980-1981 847
11-36 Relationship Between Mean Dissolved Organic Carbon, Mean
Dissolved Ortho-Phosphorus and Mean Salinity at
Mainstem Patuxent Estuary Stations, 1980-1981 848
11-37 Relationship Between Mean Total Organic Carbon, Mean
Pheophytin-a, and Mean Salinity at Mainstem
Patuxent Estuary Stations, 1980-1981 849
11-38 Relationship Between Mean Total Alkalinity, Mean Chlorides
and Mean Salinity at Mainstem Patuxent Estuary Stations,
1980-1981 850
)
11-39 Relationship Between Mean Chlorophyll-a and Mean Corrected
Chlorophyll-a Versus Mean Salinity at Mainstem Patuxent
Estuary Stations, 1980-1981 851
11-40 Relationship Between Mean Total Nitrogen and Mean Total
Unfilterable Residue Versus Mean Salinity at Mainstem
Patuxent Estuary Stations, 1980-1981 852
11-41 Relationship Between Mean pH and Mean Dissolved Nitrite
Versus Mean Salinity at Mainstem Patuxent Estuary
Stations, 1980-1981 853
11-42 Relationship Between Mean BOD5, Mean Dissolved Oxygen
Saturation and Mean Salinity at Mainstem Patuxent
Estuary Stations, 1980-1981 854
xvi
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FIGURES (continued)
Number Page
11-43 Relationship Between Mean Dissolved Oxygen, Mean Dissolved
Nitrogen and Mean Salinity at Mainstem Patuxent Estuary
Stations, 1980-1981 855
11-44 Relationship Between Mean Dissolved Ammonia, Mean Temperature
and Mean Salinity at Mainstem Patuxent Estuary Stations,
1980-1981 856
11-45 Relationship Between Corrected Chlorophyll-a and Salinity in
the Patuxent Estuary for Intensive Survey Data Taken
April 23, 1981 and Chlorophyll-a and Salinity for All
1980-1981 Slack and Intensive Survey Data 857
11-46 Relationship Between Chlorophyll-a and Salinity in the Patuxent
Estuary for Slack Tide Survey Data Taken April 27, 1981
and June 29, 1981 858
11-47 Relationship Between Chlorophyll-a and Salinity in the Patuxent
Estuary for Intensive Survey Data Taken April 23, 1981
and for Slack Tide Survey Data Taken March 19, 1981 859
11-48 Relationship Between Corrected Chlorophyll-a, Chlorophyll-a,
and Salinity in the Patuxent Estuary for Slack Tide
Survey Data Taken April 21, 1981 860 •
11-49 Relationship Between Total Alkalinity, pH, and Salinity in the
Patuxent Estuary for Slack Tide Survey Data Taken March 19,
1981 861
11-50 Relationship Between BOD5, Dissolved Oxygen Saturation and
Salinity in the Patuxent Estuary for Slack Tide Survey
Data Taken April 21, 1981 and March 19, 1981 862
ll-r51 Relationship Between Silica and Salinity in the Patuxent
Estuary for Slack Tide Survey Data Taken April 27,
1981 and March 19, 1981 863
11-52 Relationship Between Silica and Salinity in the Patuxent Estuary
for Intensive Survey Data Taken April 27, 1981 and March 19,
1981 864
11-53 Relationship Between Silica and Salinity in the Patuxent Estuary
for All 1980-1981 Slack Tide and Intensive Survey Data and
Between Total Phosphorus and Salinity for Intensive Survey
Data Taken April 23, 1981 865
xv i i
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FIGURES (continued)
Number Page
11-54 Relationship Between Dissolved Ammonia and Salinity in
the Patuxent Estuary for Slack Tide Survey Data Taken
March 19, 1981 and June 11 , 1981 866
11-55 Relationship Between Dissolved Ammonia and Salinity in
the Patuxent Estuary for Intensive Survey Data Taken
April 23, 1981 and Between Total Nonfilterable Residue
and Salinity for Slack Tide Survey Data Taken June 11,
1981 867
11-56 Relationship Between Dissolved Nitrite, Dissolved Nitrate
and Salinity in the Patuxent Estuary for Slack Tide
Survey Data Taken March 19, 1981 868
11-57 Relationship Between Dissolved Nitrite, Dissolved Nitrate
and Salinity.in the Patuxent Estuary for Intensive
River Survey Data Taken April 23, 1981 869
11-58 Relationship Between Total Dissolved Nitrogen and Salinity
in the Patuxent Estuary for Slack Tide Survey Data
Taken March 19, 1981 and Intensive River Survey Data
Taken April 23, 1981 870
11-59 Relationship Between Total Nitrogen and Salinity in the
Patuxent Estuary for Slack Tide Survey Data Taken
March 19, 1981 and Intensive Survey Data Taken
April 23, 1981 871
11-60 Space-time Domain Plot of 1970 Total Phosphorus 883
11-61 Space-time Domain Plot of 1970 NO3 884
11-62 Space-time Domain Plot of 1970 NH3 885
11-63 Space-time Domain Plot of 1970 Chlorophyl 1-a 886
11-64 Space-time Domain Plot of 1980-81 Orthophosphate 887
11-65 Space-time Domain Plot of 1980-1981 Ammonium 890
11-66 Space-time Domain Plot of 1980-81 Chlorophyll-a 891
11-67 Space-time Domain Plot of 1980-81 Chlorophyll-a 892
11-68 Space-time Domain Plot of 1980-81 of Dissolved Oxygen... 893
11-69 Sediment Oxygen Demand in the Patuxent Estuary 1980-81.. 894
11-70 Sediment Oxygen Demand in the Patuxent Estuary 1980-81.. 895
11-71 Sediment Oxygen Demand Rate in Estuarine Ecosystems 898
11-72 Patuxent Estuary Ammonium Flux From Sediments 899
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FIGURES (continued)
Number
11-73
11-74
11-75
11-76
11-77
11-78
11-79
11-80
11-81
11-82
11-83
Page
Patuxent River Longitudinal Characterization of 1980-
1981 Data for B0D5 (mg/1), alkalinity (mg/1), and
pH; Surface Station Data 900
Patuxent River Longitudinal Characterization of 1980-
1981 Data for Pheophytin-a (ug/1), Total Nitrogen
(mg/1), and Salinity (ppt); Surface Station Data 901
Patuxent River Longitudinal Characterization of 1980-
1981 Data for Chlorophyll-a (ug/1), Dissolved Reactive
Silica (mg/1), and Corrected Chlorophyl1-a (ug/1);
Surface Station Data 902
Patuxent River Longitudinal Characterization of 1980-
1981 Data for Temperature (°C), Dissolved'Oxygen
(mg/1), and TotalNonfilterable Residue (mg/1); Surface
Station Data 903
Patuxent River Longitudinal Characterization of 1980-
1981 Data for Dissolved Nitrite (mg/1), Dissolved
Ammonia (mg/1), and Chlorides (mg/1); Surface
Station Data 904
Patuxent River Longitudinal Characterization of 1980-
1981 Data for Dissolved Orthophosphorus (mg/1),
Dissolved Phosphorus (mg/1), and Total Organic Carbon
(mg/1); Surface Station Data 905
Patuxent River Longitudinal Characterization of 1980-
1981 Data for Total Dissolved Nitrogen (mg/1),
Dissolved Nitrate (mg/1), and Phosphorus (mg/1);
Surface Station Data 906
Patuxent River Longitudinal Characterization of 1980-1981
Data for Total Particulate Phosphorus '(mg/1), Dissolved
Oxygen Saturation (%), and Dissolved Organic Carbon
(mg/1); Surface Station Data 907
Patuxent River Longitudinal Characterization of 1980-1981
Data for B0D5 (mg/1), Alkalinity (mg/1), and pH; Bottom
Depth Station Data 908
Patuxent River Longitudinal Characterization of 1980-1981
Data for Pheophytin-a (ug/1), Total Nitrogen (mg/1).,
and Salinity (ppt), Bottom Depth Station Data. ^09
Patuxent River Longitudinal Characterization of 1980-1981
Data for Dissolved Reactive Silica (mg/1), Chiorophyll-a
(ug/1), and Corrected Chlorophyll-a (ug/1); Bottom
Depth Station Data 9'°
xix
-------
FIGURES (continued)
Number Page
11-84 Patuxent River Longitudinal Characterization of 1980-
1981 Data for Temperature (°C), Dissolved Oxygen
(mg/1), and Total Nonfilterable Residue (mg/1), Bottom
Depth Station Data 911.
11-85 Patuxent River Longitudinal Characterization of 1980-
1981 Data for Dissolved Nitrite (mg/1), Dissolved
Ammonia (mg/1), and Chlorides (mg/1); Bottom Depth
Station Data 912
11-86 Patuxent River Longitudinal Characterization of 1980
1981 Data for Dissolved Orthophosphorus (mg/1),
Dissolved Phosphorus (mg/1), and Total Organic Carbon
(mg/1); Bottom Depth Station Data 913
11-87 Patuxent River Longitudinal Characterization of 1980-
1981 Data for Total Dissolved Nitrogen (mg/1), Total
Phosphorus (mg/1) and Dissolved Nitrate (mg/1);
Bottom Depth Station Data 914
11-88 Patuxent River Longitudinal Characterization of 1980-
1981 Data for Dissolved Oxygen Saturation (%), Dissolved
Organic Carbon (mg/1), and Total Particulate Phosphorus
(mg/1); Bottom Depth Station Data 915
11-89 Patuxent River Longitudinal Characterization of 1980-
1981 Data for B0D5 (mg/1), Alkalinity (mg/1), and pH;
Using Surface and Bottom Depth Station Data 916
11-90 Patuxent River Longitudinal Characterization of 1980-1981
Data for Pheophytin-a (ug/1), Total Nitrogen (mg/1),
and Salinity (ppt); Using Surface and Bottom Depth
Station Data 917
11-91 Patuxent River Longitudinal Characterization of 1980-1981
Data for Chlorophyll-a (ug/1), Dissolved Reactive Silica
(mg/1), and Dissolved Oxygen (mg/1); Using Surface and
Bottom Depth Station Data 918
11-92 Patuxent River Longitudinal Characterization of 1980-1981
Data for Total Nonfilterable Residue (mg/1), Dissolved
Nitrate (mg/1), and Dissolved Ammonia (mg/i); Using
Surface and Bottom Depth Station Data 919
11-93 Patuxent River Longitudinal Characterization of 1980-1981
Data for Chlorides (mg/1), Dissolved Ortho-phosphorus
(mg/1), and Total Organic Carbon (mg/1); Using Surface and
Bottom Depth Station Data 920
11-94 Patuxent River Longitudinal Characterization of 1980-1981
Data for Dissolved Phosphorus (mg/1), Total Dissolved
Nitrogen (mg/1), and Dissolved Nitrite (mg/1); Using
Surface and Bottom Depth Station Data 921
xx
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FIGURES (continued)
Number Page
11-95 Patuxent River Longitudinal Characterization of 1980-
1981 Data for Total Phosphorus (mg/1), Total Particulate
Phosphorus (mg/1), and Dissolved Oxygen Saturation (%);
Using Surface and Bottom Depth Station Data 922
xxi
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Page
95
96
97
98
102
103
105
107
110
111
112
113
114
115
116
TABLES
Patuxent Estuary Survey Dates and Dates of Spring
and Nssp Tides
Station Description of Patuxent River Slack Tide and
IWQS Stations
Station Description for Patuxent River Lateral Slack
Tide Stations •••••••••••••••••••••
Times at Which Samples Were Collected at Each Station
and Substation for Each Slack Tide Survey in the
Patuxent River
Predicted Times of Minimum Current During IWQS
Intensive Water Quality Survey Schedule ......
Slack Tide Water Survey Sampling Schedule
Slack Tide Water Survey Sampling Schedule With Lateral
Stations
Analytical Procedures for Patuxent Estuary Program
Sample Preservation and Holding Time for Patuxent Estuary .
Standard Stability and/or Frequency for Estuarine Water"
Quality Program Preparation
Precision and Accuracy for Ammonia Nitrogen Estuary
Program . . . .
Precision and /Accuracy for Filtered Total Persulfate
Nitrogen.
Precision and Accuracy for Ortho-phosphate.
Precision and Accuracy for Total Persulfate Nitrogen and
Phosphorus
xxi i
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TABLES (continued)
Number Page
2-16 Precision and Accuracy for Filtered Total Persolfate
Phosphorus H?
2-17 Precision and Accuracy for Silicate 118
2-18 Precision and Accuracy for Alkalinity 119
2-19 Precision and Accuracy for Nitrite Nitrogen 120
2-20 Precision and Accuracy for Nitrate Nitrogen 121
2-21 Precision and Accuracy for Suspended Solids and
Dissolved Organic Carbon 7 122
2-22 Methods and Preservation Techniques Used for Monitoring
Subwatersheds Chemical Export 127
3-1 Percent Increase of Population From 1980-2000 for the
Patuxent River Basin Counties 133
3-2 Comparison of the 1969 Population Projections for the
Year 1980 133
3-3 Existing (1980) and Projected (2000) Waste Water Flows
in the Patuxent River Basin 134
5-1 Estimated Yearly Rainfall Loads to the Patuxent Basin
and Water Surface From Bulk Precipitation Measurements 152
6-1 Description of Non-Point Source Monitoring Stations 160
6-2 Soil Survey Data and Interpretations for Howard County
Soil Conservation District 208 and Grey Farm
Subwatershed 162
6-3 Peak Rainfall Frequencies or Storm Discharge for Zepp
Farm and Grey Farm 164
xxi ii
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TABLES (continued)
Number Page
6-k Approximate Crop and Land Utilization for Zepp Farm
and Grey Farm During 1981 Sampling Period 165
6-5 Description of Exact Locations of the NPS Monitoring
Sites and Rainfall Gauges 166
6-6 Statistical Summary of Patuxent River NPS Watershed
Chemical Exports (lb/acre), All Sites 167
6-7 Statistical Summary of Patuxent River WPS Watershed
Chemical Exports (lb/acre), All Agricultural Sites . . 168
6-8 Statistical Summary of Patuxent River NPS Watershed
Chemical Exports (lb/acre), Patuxent Park 169
6-9 Statistical Summary of Patuxent River NPS Watershed
Chemical Exports (lb/acre), Deale A 170
6-10 Statistical Summary of Patuxent River NPS Watershed
Chemical Exports (lb/acre), Deale B . ........ . 171
6-11 Statistical Summary of Patuxent River NPS Watershed
Chemical Exports (lb/acre), Zepp Farm 172
6-12 Statistical Summary of Patuxent River NPS Watershed
Chemical Exports (lb/acre), Grey Farm 173
6-13 Statistical Summary of Patuxent River NPS Watershed
Chemical Exports (lbs/acre/in), All Sites 174
6-1^ Statistical Summary of Patuxent River NPS Watershed
Chemical Exports (lbs/acre/in), All Sites 175
6-15 Statistical Summary of Patuxent River NPS Watershed
Chemical Exports (lbs/acre/in), Patuxent Park 176
6-l6 Statistical Summary of Patuxent River NPS Watershed
Chemical Exports (lb/acre/in), Deale A 177
6-17 Statistical Summary of Patuxent River NPS Watershed
Chemical Exports (lb/acre/in), Deale B 178
6-18 Statistical Summary of Patuxent River NPS Watershed
Chemical Exports (lb/acre/in), Zepp Farm 179
6-19 Statistical Summary of Patuxent River NPS Watershed
Chemical Exports (lb/acre/in), Grey Farm 180
xxiv
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TABLES (continued)
Number Pngp
6-20 Statistical Summary of Patuxent River NPS Watershed
Chemical Exports (lb/acre/year)-All Sites 181
6-21 Statistical Summary of Patuxent River NPS Watershed
Chemical Exports (lb/acre/year)-All Agricultural
Sites 182
6-22 Statistical Summary of Patuxent River NPS Watershed
Chemical Exports (lb/acre/year)-Patuxent Park 183
6-23 Statistical Summary of Patuxent River NPS Watershed
Chemical Exports (lb/acre/year)-Deale A .. 184
6-21* Statistical Summary of Patuxent River NPS Watershed
Chemical Exports (lb/acre/year)-Deale B 185
6-25 Statistical Summary of Patuxent River NPS Watershed
Chemical Exports (lb/acre/year)-Zepp Farm 186
6-26 Statistical Summary of Patuxent River NPS Watershed
Chemical Exports (lb/acre/year)-Grey Farm 187
6-27 Relative Comparison of Estimated Average Forested
Watershed Chemical Export to Estimated Average
Agriculture Watershed Chemical Export (lb/acre/in)
1980-1981 188
6-28 Estimated Average Potential Watershed Chemical Export of
Total Phorphorus During Storm Events to the Patuxent
River Basin 189
6-29 Estimated Average Potential Watershed Chemical Export of
Total Nitrogen During Storm Events to the Patuxent
River Basin 190
6-30 Chemical Export Functions for the Patuxent River NPS
Watersheds (lb/acre/inch of rain) versus Storm
Flow (gallons) 191
6-31 Chemical Export Functions for the Patuxent River NPS
Watershed (lb/acre) versus Total Rainfall , 198
6-32 Chemical Export Functions 'for the Patuxent River WPS
Watersheds (lb/acre) versus Flow In Gallons 202
6-33 Chemical Export Functions Developed From Multiple Linear
Regressions (5 independent variables) 206
XXV
-------
TABLES (continued)
Number Page
6-3^ Chemical Export Functions Developed From Multiple Linear
Regressions (9 independent variables) 208
6-35 Bulk Precipitation Quality at Patuxent Park NPS Station
From September 1980 Through November 1980 211
6-36 Bulk Precipitation Quality at Patuxent Park NPS Station
From December 1980 Through February 1981 212
6-37 Bulk Precipitation Quality at Patuxent Park NPS Station
From March 1981 Through June 1981 213
6-38 Bulk Precipitation Quality at Patuxent Park NPS Station
From July 1981 Through August 1981 214
7-1 Statistical Summary of the Patuxent River Slack Survey
Data for 1980-1981. 330
7-2 Statistical Summary of the Patuxent River Slack Survey
Data for 1980-1981 Divided By Surface, Middle and
Bottom Depths 331
8-1 Statistical Summary of the Patuxent River Monthly Water
Quality Variables, 1980-1981, at Salinity Regions
of 0-3 ppt, 3.1-10 ppt and Greater Than 10 ppt 435
9-1 Statistical Summary of the Patuxent River Intensive
Survey Data For 1980-1981 625
9-2 Statistical Summary of the Patuxent River Intensive
Survey Data for 1980-1981, Grouped According
to Surface, Middle, and Bottom Depths 626
10-1 Yearly Mean Dissolved Oxygen in the Patuxent Estuary,
1936-1981 635
10-2 Yearly Mean Dissolved Oxygen in the Upper Patuxent
Estuary, 1936-1981 636
10-3 Yearly Mean Dissolved Oxygen in the Lower Patuxent
Estuary, 1936-1981 637
10-U Yearly Mean Dissolved Oxygen for the Month of August in
the Patuxent Estuary 638
xx vi
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TABLES (continued)
Number Page
10-5 Yearly Mean Dissolved. Oxygen for the Month of August
in the Upper Patuxent Estuary 641
10-6 Yearly Mean Dissolved Oxygen for the Month of August
in the Lower Patuxent Estuary 642
10-7 Dissolved Oxygen Deficits in the Lover Patuxent Estuary,
1936-1981 677
10-8 Dissolved Oxygen Deficits in the Upper Patuxent Estuary,
1936-1981 681
10-9 Dissolved Oxygen Deficits in the Patuxent Estuary,
1936-1981 685
10-10 Dissolved Oxygen Deficits (DOD) in the Upper Patuxent
Estuary, By Decades 689
10-11 DOD in the Lower Patuxent Estuary, By Decades 690
10-12 DOD in the Patuxent Estuary, By Decades 691
10-13 DOD in the Lower Patuxent Estuary at Various Depths,
1936-1981 1 692
10-lU DOD in the Upper Patuxent Estuary at Various Depths,
1936-1981 698
10-15 Averaged DOD in the Patuxent River at Various Depth Ranges. 704
10-16 Averaged DOD in the Upper Patuxent River at Various Depth
Ranges 705
10-17 Averaged DOD in the Lower Patuxent River at Various Depth
Ranges 7°6
10-18 Monthly DOD in the Upper Patuxent Estuary, 1936-1981. . . . 707
10-19 Monthly DOD in the Lower Fsrtuxent Estuary, 1936-1981. . . . 712
10-20 Upper Patuxent River DOD for the Month of August at Various
Depths j ... "...
10-21 Lower Patuxent River DOD for the Month of August at Various
Depths 718
xxvi i
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TABLES (continued)
Mumber Page
10-22 Patuxent River DOD in August at Various Times of the
Day and Depths 722
10-23 Upper Patuxent River DOD in August at Various Times
of Day and Depths 726
10-2*+ Lower Patuxent River DOD in August at 'Various Times
of Day and Depths 730
10-25 July and August DOT) in the Patuxent Estuary at Various
Depths ' 734
10-26 July and August DOD in the "Upper Patuxent Estuary at
'Various Depths 738
10-27 July and August DOD in the Lover Patuxent Estuary at
Various Depths 742
10-28 Upper Patuxent River DOD, January Data, 746
10-29 Lower Patuxent River DOD, January Data 747
10-30 Upper Patuxent River DOD, February Data 748
10-31 Lower Patuxent River DOD, February Data 749
10-32 Upper Patuxent River DOD, March Data 750
10-33 Lower Patuxent fliver DOD, 'March Data 752
10-3*1 Upper Patuxent River DOD, April Data 754
10-35 Lower Patuxent River DOD, April Data 756
10-36 Upper Patuxent River DOD, May Data 757
10-37 Lower Patuxent River DOD, "May Data 758
10-38 Upper Patuxent River DOD, June Data 760
10-39 Lower Patuxent River DC®, June Data 761
10-1*0 Upper Patuxent River DOD, July Data 763
10-141 Lower Patuxent River DOD, July Data 765
10-1+2 Upper Patuxent River DOD, September Data . 768
xxviti
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TABLES (continued)
Number Page
10-1+3 Lower Patuxent River DC®, September Data 770
10-1+1+ Upper Patuxent River DOD, October Data , 773
10-1+5 Lower Patuxent River DOD, October Data 774
10-1+6 Upper Patuxent River DOD, November Data 776
10-1+7 Lower Patuxent River DOD, November Data 777
10-1+8 Upper Patuxent River DOD, December Data 779
10-1+9 Lower Patuxent River DOD, December Data 780
11-1 Correlation Coefficients of Various Water Quality
Variables to Determine Linear Associations , , . , 816
11-2 Correlation Coefficients Between Nutrient and Salinity
Stratification at Stations in the Lower Patuxent
River 820
11-3 Correlation Coefficients Between Transformed Values
of Nutrient and Salinity Stratification at
Stations in the Lower Patuxent River 821
11-1+ Patuxent River Longitudinal Phytoplankton Results for
July 1980 823
11-5 Patuxent River Longitudinal Phytoplankton Results for
April 1981 824
11-6 Patuxent River Surface Chlorophyll-a and Pheophytin-
a Data 832
11-7 Patuxent River Longitudinal Water and Sediment
Bacteria Measurements For July 23-21+, 1980 . , , , 833
11-8 Patuxent River Longitudinal Water and Sediment
Bacteria Measurements for August 21, 1980 . , . , 834
11-9 Patuxent River Longitudinal Water and Sediment
Bacteria Measurements for April 20-21, 1981 . , . 835
11-10 Photosynthetic and Belated Measurements in the
Patuxent River 836
xxix
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TABLES (continued)
Number Page
1-11 Summary of Lower Patuxent Estuary Plankton Productivity
(Pn) and Night Time Respiration (Rm) During October
1980-August 1981 844
1-12 Comparison of Phytoplankton Demand and Bethic
Remineralization of Nitrogen and Phosphorus in the
Lower Patuxent Estuary, 1980-1981 845
1-13 Univariate Linear Relationships Between Water Quality
Variables and Silica From Calculated Mean Station
Values During 1980-1981 872
1-14 Univariate Linear Relationships Between Water Quality
Variables and Salinity From Calculated Mean
Station Values During 1980-1981 873
1-15 Statistical Summary of Patuxent River Intensive and
Slack Survey Data, 1980-1981 ; 874
1-16 Statistical Summary of Patuxent River Intensive and
Slack Survey Data With 1980 and 1981 Data Separated.. 875
1-17 Statistical Summary of Patuxent River Intensive and
Slack Survey Data for Surface, Middle, and Bottom
Depths, 1980-1981 876
1-18 Statistical Summary of Patuxent River Intensive and
Slack Survey Data for Surface, Middle, and Bottom
Depths with 1980 and 1981 Data Separated 878
1-19 Statistical Summary of Patuxent River Water Quality
Variables, 1980-1981, With Salinity Regimes (a)
0-3 ppt, (b) 3.1-10 ppt and (c) greater then 10 ppt.. 881
1-20 Sediment Oxygen Demand and Net Nutrient Fluxes Occurring
in the Lower Patuxent River, October 1980-November
1981 888
1-21 Summary of Upper Patuxent Estuary Sediment Nutrient
Fluxes, 1979-1980 889
1-22 Benthic Respiration in the Patuxent River 1980-1981... 896
1-23 Patuxent River Lateral and Center Station Means...*... 923
xxx
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LJ.3 1 ur HDDKJiV JLAliUNO A1NLI ainjJULS
ABBREVIATIONS
B0D5 —biochemical oxygen demand in five days
BOD20 —biochemical oxygen demand in twenty days
BOD30 —biochemical oxygen demand in thirty days
COD —chemical oxygen demand
CFD —cummulative frequency distribution
CV —coefficient of variation
DIP —dissolved organic phosphorus
DN —dissolved nitrogen
DO —dissolved oxygen
DOC —dissolved organic carbon
DOD —dissolved oxygen deficit
DOS —dissolved oxygen saturation
DP —dissolved phosphorus
ft/sec —feet per second
IWQS —intensive water quality surveys
kg —kilograms
lb/acre —pounds per acre
lb/acre/in —pounds per acre per inch of rain
lb/acre/year —pounds per acre per year
MGD —million gallons per day
mg/l —milligrams per liter
MPN —most probable number
NHg —ammonia
1TC>2 —nitrite
NOg —nitrate
NPS —non-point source
NPDES —national pollutant discharge elimination system
PO^ —phosphate
ppt —parts per thousand
r —regression coefficient
r2 —squared correlation coefficient
SD —standard deviation
STP —sewage treatment plant
TKN —total kjeldahl nitrogen
TN —total nitrogen
TOC —total organic carbon
TON —total organic nitrogen
TP —total phosphorus
TPN —total particulate nitrogen
TPP —total particulate phosphorus
TSS —total suspended solids
yg/1 —micrograms per liter
USGS —United States Geological Survey
N:P --the ratio of nitrogen to phosphorus, by weight.
xx xi
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ACKNOWLEDGEMENTS
The authors thank the following individuals. Lee Zeni, who supported
this data interpretation. Dave Flemer for his encouraging scientific
discussions. Bruce Nierwienski, Mike Davis, Sandy Cainfield, Minnie Cohen,
and Rebecca Himmelmen, all who worked diligently in data management aspects
of the project. Aftab Hassan, and Jerry Oglesby for statistical
discussions. Dave Lively for file management approaches. Steve Domotor is
thanked for proofing the final draft and for editorial changes.
Ed Kruger and the Philadelphia Academy of Natural Sciences staff are
acknowledged for excellent performance of the estuarine data collection
program. Doug Dixon and the Versar staff who monitored the non-point
source watersheds. Biospherics Incorporated and the University of Maryland
who collected the biological and sediment processes data. Bill Boicourt is
acknowledged for the data collection effort involving current speed and
direction, in the lower estuary. Donna Klein, Rose Safford, and Jackie
Chaney are thanked for their secretarial support.
xxxii
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SECTION 1
Introduction
This study was one of five watershed studies funded by the United
States Environmental Protection Agency, Chesapeake Bay Program. The study
was designed to provide non-point source chemical export data for typical
subwatersheds within the Chesapeake Bay Basin, as well as to provide
information concerning the ambient concentrations of nutrients within the
tidal river and estuary of the Patuxent River system. This river system
was chosen for study by the State of Maryland, Department of Natural
Resources because of the public concern for maintaining an economically
important fishery and shellfish industry. Recent reports have indicated
that land use activities have Increased nutrient enrichment. The Patuxent
River Watershed has experienced greater population increases and land use
changes than most other watersheds within the Chesapeake Bay system.
Therefore a research monitoring study was selected for this basin in order
to provide additional information for management of its water resources and
biological resources.
The results of the study have been used by the Chesapeake Bay Program
for developing baywide non-point source (NPS) loading rates and for
characterization of the nutrient enrichment of the Patuxent estuary
relative to other subestuarles within the Chesapeake Bay Basin. Data from
this study are also being used for water quality modeling purposes.
This report constitutes an initial interpretation of what is to date
the most intensive study of this estuarine system. Careful documentation
of the data collection efforts has been included in this report for future
nutrient enrichment and habitat assessment comparisons. All the figures
and tables in this text can be found in the appendices.
Executive Summary
Data collected during this study indicates the Patuxent estuary
sediment oxygen demand measurements are among the highest values measured
and reported in the literature (figure 11-71). High sediment oxygen demand
is a classical example of secondary impacts from nutrient enrichment.
Future high sediment oxygen demands (SOD) cannot be forecasted to date.
Nutrient budgets were calculated from data collected during this
intensive study In order to Indicate to managers and researchers the
potential major sources of nutrient enrichment. The results of these
budgets shown in figures 5-1 through 5-5 indicate the major sources of
nutrients to the estuary during this study. Data indicate the major
sources of total nitrogen are from fluvial sources at Rt. 50, followed by
the lower estuary sediment flux and NPS loads. The data also Indicate
1
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that there is a net exchange of total nitrogen out of the estuary. Figure
5-2 shows the dissolved NO^ + NO3 budget. This budget indicates that
the largest source to the estuary Is also from fluvial sources above Rt.
50, followed by a source from Chesapeake Bay.
The ammonia (figure 5-3) budget indicates the sediment flux in the
upper and lower river may be the greatest source followed by the source
from Chesapeake Bay. The total phosphorus budget (figure 5-4) indicates
that the lower estuary sediment flux and non-point sources in the lower
estuary may be the same order of magnitude and presents the largest
sources. The dissolved orthophosphorus budget indicates that the lower
estuary sediment flux and fluvial sources above Rt. 50 are the major
sources followed by the potential source from Chesapeake Bay.
Theoretical conservative mixing diagrams also indicate potential
sources of nutrients in the estuary. These are shown in figures 11-34
through 11-59. These diagrams obviously indicate high variability from
month to month but on a seasonal and annual basis trends are apparent. For
example, a mid to lower estuary peak of orthophosphorus, dissolved
phosphorus, total phosphorus, chlorophyll-a and silica was observed (see
figures 11-34, 11-35 and 11-36) during the study.
These diagrams support the view, as well as the phosphorus budgets
that a major source of phosphorus to the estuary water column is below the
upper tidal river (Route 50 bridge).
The estimated flushing time of the tidal river and estuary is around
300 days (figure 4-15). This information, in conjunction with the total
nitrogen conservative mixing diagram (figure 11-40), indicates the estuary
serves as a sink for most of the fluvial nitrogen. If the estuary serves
as a sink for nitrogen, (including nitrate, nitrite, and dissolved nitro-
gen, see figures 11-34, 11-41, 11-43) one would expect high sediment-nutri-
ent fluxes of inorganic nitrogen, especially ammonia due to reminerali-
zatlon of organic matter, and associated high sediment oxygen demand due to
settling out and resulting decay of organic material. Figure 11-70 shows
ammonium fluxes from sediments and the budget for ammonia indicates a major
source of ammonia in the estuary is from the sediments. Figure 11-44 also
indicates that ammonia behaves nearly as a conservative substance in the
water, except in the lower estuary where a source is indicated (due to
higher bottom concentrations). Thus, the fate of nitrogen introduced into
the estuary appears to be that it remains in the system for a relatively
long period and is remlnerallzed by sedimentation and biological processes,
yielding high ammonia concentrations in bottom waters.
The role that sediments play in regulating water column concentrations
in the Patuxent estuary appears to be important, as reported by other
studies (57,65).
2
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As part of this study D'Elia (16) calculated that the sediments may
supply approximately 30% of the daily phytoplankton demand for water column
ammonium. This fact indicates that the sediments may be responsible for
controlling water column concentrations occasionally.
A typical concern in estuarine management is determination of the
limiting factors to plant or algal production. Although temperature is one
of the most dominant controlling factors, knowledge of the controlling
nutrient has been used to focus management scenarios for point and
non-point source nutrient controls.
Unfortunately, the limiting nutrient affecting plant production is not
consistent spatially and temporally which makes management strategies dif-
ficult to develop as well as to determine their effectiveness. An evalu-
ation of the redfield ratio (N/P ratio) was conducted using data collected
during this study. This analysis showed that the apparent limiting nutri-
ent varies longitudinally (figures 7-20, 7-21) as well as monthly. A mul-
tiple regression analysis indicated that approximately 75% of the varia-
bility of the redfield ratio could be explained (see squation 11-1) by
location, (i.e. nautical mile) salinity, timing of the survey to the
previous storm event and characteristics which describe the size of the
previous storm event, for example peak daily CFS, average daily CFS during
storm event, and sum of daily CFS from beginning to the end of the storm.
From this analysis it can be inferred that storm events and their associ-
ated export of nutrients cause pulses of nutrients to enter the estuary,
which in turn determine the limiting nutrient. From a management perspec-
tive, this clearly shows the need for considering the effect of storm
events and land use activities on estuarine management.
One measure of the suitability of an aquatic habitat for fisheries and
shellfish production is the level of dissolved oxygen needed for growth and
reproduction. The effects of nutrient enrichment are expressed in the
dissolved oxygen. The effect of increasing nutrient enrichment should be
observed through low dissolved oxygen in bottom waters. Historical
dissolved oxygen measurements (approximately 5,000) were collected from
historical reports and studies conducted in the mainstem Patuxent River.
Statistical analyses were performed in order to determine trends. Figure
10-33 shows a plot of the mean dissolved oxygen deficit throughout the
mainstem estuary. Summer deficits average around 2 mg/1 with a maximum
deficit around 2.3 mg/1 in September. Figure 10-29 clearly shows the mean
dissolved oxygen deficit is around 3 mg/1 in the lower river (10-24 ppt
salinity) at depths greater than 30 feet. Yearly mean dissolved oxygen
plots (figures 10-1 to 10-4) show no apparent trends for the entire river.
However, a strong trend towards lower dissolved oxygen is observed in
figure 10-12 for a river segment above Western Branch, based upon seasonal
mean dissolved oxygen. A lower dissolved oxygen trend is observed (figure
10-31) when dissolved oxygen deficits are regressed for the upper estuary.
A similar trend is indicated in the lower estuary when all values are
regressed versus time (see figure 10-32, line 6) although it is not as
apparent as in the upper estuary. In section ten of this report a detailed
3
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presentation in the form of tables shows dissolved oxygen deficits
categorized by months, depths and time of day. These tables clearly show
the lack of consistent monitoring in the estuary, especially in deeper
waters in the lower estuary. Lack of consistent historical measurements
indicates ambiguous results when more detailed statistical analyses of
dissolved oxygen deficits are performed.
The relative importance of freshwater flow effects on nutrient
concentrations were examined by conducting regression analyses between
station nutrient concentrations, surface to bottom salinity differences and
average freshwater inflow before the estuarine water quality surveys. This
analysis was performed to indicate the effect of advective processes on
stratification. The result of this analysis is shown in table 11-3 and
indicates that stratification at each station may be uniquely controlled.
However, on the average, stratification (indicated by surface to bottom
salinity differences) and freshwater inflow can explain around 50% of the
variability of nutrient concentrations. Further analyses should be
performed to more fully explain dominant physical processes at different
longitudinal stations.
The relative importance of NPS loads to the basin are shown in the
nutrient budgets. Table 6-28 indicates the predominant NPS loads of total
phosphorus and total nitrogen comes from agricultural lands. This data is
consistent with other estimates (28). Table 6-27 shows the ratio of
agricultural to forested chemical export during storm events. Data from
this study indicate that total phosphorus is 6-7 times higher in agri-
cultural runoff than from forested land runoff. Total suspended solids
(suspended sediment) was five times higher in agricultural runoff from the
sites monitored in this study.
Fluvial sources above Route 50 are the major source of NO2 + NO3
(figure 5-2), with Chesapeake Bay being the major source. Non-point source
export of ammonia on a basin basis appears insignificant. Total phosphorus
NPS export i6 indicated as the major source to the estuary as shown in
figure 5-4. NPS chemical export of orthophosphorus is insignificant
compared to the sediment flux in the estuary.
Figures 11-89 through 11-95 show the results of applying the duncan
multiple range test for characterizing zones of chemical similarity from
data collected in the water quality surveys. These plots as well as others
shown in section eleven of the report indicate spatial locations which have
relatively unique concentrations when compared to all of the other main-
stream stations. In many cases this analysis identified the surface water
concentrations as a unique class in the turbidity maximum region of the
estuary. Unique zones were identified in the turbidity maximum region for
silica, salinity, B0D5, total suspended solids, and total organic carbon.
Unique zones were identified in the lower estuary for surface water pH;
bottom water alkalinity and chlorophyll-ji near the mouth of the estuary;
silica in bottom water and surface water at the mouth of the estuary. It
is interesting to note a unique zone was identified for dissolved oxygen
4
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and dissolved nitrate. This zone showed the lowest average concentrations
for both dissolved oxygen and dissolved nitrate. This zone or region of
the estuary occurs downstream of the mid-estuary sill shown by the low
mid-river mean hydraulic depth in figure 4-6. This zone is also the region
where lower estuary dissolved oxygen values have historically been close to
zero. Observations from the slack, water surveys indicate this may be a
region or natural upwelling of bottom anoxic waters as tidal energy forces
the water upriver. The mid-river sill, as well as the fact that the rate
of change of water depth increases in this area makes the upwelling more
likely. Plots of temperature and salinity profiles in this region of the
estuary also indicate inversions (higher salinity and lower temperature in
surface waters) of the water column. High chlorophyll-a^ values in this
upper region of the lower estuary may also be due to upwelling phenomena.
Figure 11-30 shows dinoflagellates (cells/ml) increasing in this region
where upwelling may predominate under certain circumstances.
Conclusions
Data collected and initially analyzed under this grant indicate that a
trend exists for loweS: dissolved oxygen above Western Branch, based on a
seasonal analysis. Fluvial inputs (including point source loads) represent
the greatest sources of NO^+NO^, ortho-p, total nitrogen, and total
phosphorus. Simple nutrient budgets also indicated Chesapeake Bay may be a
source for NO2+NO3 (34.6%), NH$ (16%) and total nitrogen (20.9%). A
significant source of total phosphorus from NPS (40% of the total) to the
estuary is indicated. Upwelling of lower estuary water, rich in nutrients
from sediment-nutrient fluxes may be responsible for episodes of high
chlorophyll-a_ in the lower estuary.
Recommendations
Investigations should continue to determine the future trend of
lower dissolved oxygen in the upper estuary.
A statistically based monitoring program should be established
around Sheridan point and above, in order to determine if
historically low dissolved oxygen is increasing in extent and
frequency of occurrence.
The above monitoring should be coupled with dynamic monitoring
in order to determine to what extent lower estuary high
chlorophyll-^ may reflect periods and processes related to
upwelling of bottom, nutrient rich waters, characteristic of
phytoplankton derived from Chesapeake Bay.
A detailed monitoring of sediments and sedimentation is
necessary for developing a baseline of SOD and Sediment
Nutrient Fluxes.
5
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Once completed, the varlability over time with respect to SOD
and Sediment Nutrient Fluxes should be monitored to determine
the effectiveness of point and non-point source controls.
Monitoring of dissolved oxygen in oyster bed areas will be
needed to determine if these living resources are being
impacted by point or non-point source land use activities.
Data collected during this study should be used to calibrate
and validate a real-time model of water quality and hydro-
dynamics .
Real time hydrological simulation modeling will be needed in
order to prioritize subwatersheds in the basing for applying
best management practices. Data from this study should be
used for this purpose.
6
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SECTION 2
METHODS
Mainstern River and Estuary Sampling Methodology
Estuary and upper river sampling stations were monitored by the Phila-
delphia Academy of Natural Sciences between June 1980 and August 1981. This
program included seventeen slack water surveys and two twenty-four hour
surveys. Figure 2-1 indicates the location of the sample sites monitored
during slack tide and intensive water quality surveys. Figure 2-2 shows
the locations of slack tide and lateral slack tide stations. The dates of
the slack tide and intensive water quality surveys are shown in Table 2-1.
Station identification numbers, latitude and longitude and general site
descriptions are given in Table 2-2 for the slack survey stations and
intensive water quality surveys (24-hour surveys). Table 2-3 indicates
sample site descriptions for the lateral slack tide stations sampled during
the slack water surveys immediately preceding each intensive survey.
The intensive water quality surveys (IWQS) were designed to provide
information concerning lateral and vertical homogeneity of the water column
variables. During the two IWQS, samples were collected at all stations
(except the Western Branch wastewater treatment plant) approximately every
two hours for the 24 hour period. The time of sample collection during
each slack water survey is indicated on Table 2-4 as well as the expected
time of minimum current based upon tide tables. Table 2-5 indicates the
time of expected minimum current at five locations during the IWQS
conducted July 24-25, 1980 and April 23-24, 1981. Table 2-1 also indicates
the date of the surveys and the expected date of spring and neap tides
during the study period.
All compatible data was stored in the State of Maryland Water Quality
File and STORET under the station codes given. Variables measured for this
program included stage height, current velocity and direction, dissolved
oxygen, pH, temperature, relative humidity, secchi disc, light penetra-
tion/extinction, total chlorophyll-a, pheophytin, BOD5 and B0D20» total
organic carbon or dissolved organic carbon, chemical oxygen demand, total
persulphate phosphorus, ortho-phosphate, nitrate (NO3-N), nitrite
(NO^-N), ammonia (NH3-N), total persulfate nitrogen, total suspended
solids (total non- filterable residue), dissolved reactive silicate
(Si02), total alkalinity, fecal coliforms and chlorides. Tables 2-6,
2-7, and 2-8 indicate the sample design and schedule for the different
types of survey measurements taken at various depths for each survey type.
7
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Figure 2-1 Patuxent River intensive and slack tide sampling stations,
(ref. Table 2-2 for station discription).
8
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Figure 2-2 Patuxent River slack and lateral slack tide sampling
stations, (ref. Table 2-2 and 2-3 for station discription).
9
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The following is a description of the variables measured and the
methods used:
Stage height measurements were made using General Oceanics Model 6040 tape
recording tide gauges placed at stations XDE2599 and PXT0402. Stage height
(meters) and water temperature (°C) were recorded at 15 minute intervals
at station XDE2599 from June 24 to December 9, 1980 and from March 11 to
August 24, 1981. At station PXT0402 measurements were recorded from June
24 to September 1, 1980 and from May 21 to August 24, 1981. Data has been
placed into STORET. Stage height data was not normalized to any sea level
datum.
Discharge measurements were made at station WXT0045 each time a sample
was taken during the IWQS and during each slack water survey following the
procedures outlined by the United States Geological Survey (1 and 2). A
factory calibrated Marsh-McBirney Model 201 Portable Current Meter was
used.
Discharge data for station PXT0603 was obtained each time a water
sample was collected from the United States Geological Survey (USGS) in
Towson, Maryland. The USGS maintains a monitoring station at the Route 50
bridge crossing the Patuxent River. Discharge data for stations WXT0045
and PXT0603 were expressed as cubic feet per second.
Water velocity and direction were measured during the intensive
surveys and all slack water surveys according to the schedule shown in
Tables 2-6, 2-7 and 2-8. At all stations and substations, three replicates
were obtained, consecutively, at bottom, middle and surface depths. Mean
velocity for each depth was calculated and expressed as feet per second.
Factory calibrated Marsh-McBirney Model 527 electromagnetic water current
meters were used to collect these data from boats anchored on station.
Meter measurements of dissolved oxygen, temperature and salinity were
made as shown in Tables 2-6, 2-7, and 2-8. Dissolved oxygen was determined
with YSI Model 57 oxygen meters, calibrated in the laboratory and prior to
use at each station. Salinity and temperature measurements were made with
either YSI Model 33 SCT meters or Beckman Model RS5-3 salinometers.
Measurements of pH were obtained in the laboratory using a Corning Model
610 pH meter.
Measurements of wind velocity and direction, air temperature, relative
humidity and barometric pressure were obtained according to the schedule
shown in Tables 2-6, 2-7 and 2-8. A Bendix anemometer-wind vane, model
ML-446/PMQ-3 or Sierra-Misco Model 1039 wind speed-direction meters and
Sylva Type 15 compasses were used to determine wind velocity and direction.
Wind velocity data were expressed in knots.
Relative humidity was measured with standard sling psychrometers
manufactured by Taylor Instrument Company. Wet and dry bulb temperatures
were obtained and relative humidity determined from tables provided by the
manufacturer.
10
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Thomen Pocket Altimeter/Barometers, Model 2000-11, were used to
measure barometric pressure. These data are recorded In mm of Hg.
Light penetration/extinction measurements were made with a Li-Cor
Model L.I-185A light meter equipped with a Li-1925 underwater quantum sensor
for measuring submerged, photosynthetically available, radiation. Incident
light was measured approximately one inch below the water's surface. The
sensor was then quickly lowered to a depth where light penetration (uE
units) was 1% of the surface measurement. This depth was recorded as the
depth of 1% light penetration.
Analytical procedures used for the slack surveys and IWQS are shown in
Table 2-9. Table 2-10 indicates the maximum holding times and preservation
techniques used. All methods used are suitable for fresh or ocean water.
Quality Assurance
A quality assurance program was conducted throughout this sampling
program. Stock standards were prepared for each method using distilled
deionized water. Working standards were prepared from the stock solution.
Table 2-11 indicates the stability and/or frequency of standard prepara-
tion. A precision and accuracy program was conducted for these surveys and
the results are shown in Tables 2-12 through 2-21. The method for separa-
tion of samples into respective aliquots is shown in Table 2-3.
Nitrite, nitrate and ortho-phosphorus analyses were conducted at the
Benedict Estuarine Research Laboratory, by the Philadelphia Academy of
Natural Sciences during 1980. Samples were separated into respective
aliquots, preserved as indicated in Table 2-10. Samples requiring the
shortest holding time were analyzed first (i.e., ortho-phosphorus and
nitrite). During 1981 all samples remained frozen until time of analysis.
A Technicon Autoanalyzer (AAII) was used to determine NO^, NO3,
ortho-phosphorus, SiC>2, NH3, total phosphorus and total nitrogen.
Alkalinity, COD and chlorides were titrated; whereas, solids
(nonfilterable), B0D5 and 20, and fecal coliform (MPN) followed the
procedures shown in Table 2-9.
Precision and accuracy were determined for alkalinity, solids (total
nonfilterable residue) nitrite, nitrate, ammonia, ortho-phosphorus,
silicate, total persulfate nitrogen and total persulfate phosphorus. No
program was conducted for water quality characteristics which were deleted
later in the study, i.e. chlorides and COD. Determination of precision
involved analysis of seven replicates run over the entire duration of an
analysis. Precision has been reported with mean, standard deviation and
coefficient of variation.
To determine accuracy, selected samples were spiked and percent
recovery was calculated. New standards were prepared for each survey. In
order to determine if any matrix effect occurred due to salinity, spiked
11
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samples were selected from saline and fresh waters. Precision and accuracy
were continually monitored throughout the sampling period and numerous
duplicate and triplicate analyses were run in order to maintain a check on
precision. In addition, EPA quality control samples were analyzed as a
quality control check.
Tables 2-12 through 2-21 indicate the letter code assigned to samples
chosen for quality assurance and applies to samples within a water quality
characteristic. That is, a sample used for precision which was designated
A, then refers to that same sample which was spiked for the determination
of accuracy. Spiked samples are also marked to indicate whether a fresh
water or saline sample was used.
In addition to the water quality sampling program described above, the
University of Maryland collected data for this study in the lower estuary
at six stations shown in Figure 2-3. Sample methods are the same as those
shown in Table 2-9. In addition, the University of Maryland also collected
particulate organic nitrogen and particulate organic carbon using the
Perkin Elmer 240B CHN Analyzer. These measurements were made at the same
time sediment nutrient flux and respiration measurements were made at the
approximate same time period that water column measurements were conducted.
Biological Sampling Methods
Measurements related to the biological community composed of primary
producers (i.e. phytoplankton) and reducers (i.e. bacteria) were made.
These measurements were conducted by Biospherics Incorporated for this
study. Three tasks were performed and are described below. They are
longitudinal field collections of phytoplankton, productivity measurements,
and collection of water and sediment samples for nitrification bacterial
identification. Sediment oxygen demand measurements, discussed later in
this section, were also measured.
Station location of plankton grab stations are shown in Figure 2-4.
Plankton were collected at eleven sample sites. These sites corresponded
with the slack water and intensive survey sites described previously.
Dates of collection were July 23-24, 1980 and April 20-21, 1981, the same
time period that the 24 hour intensive water quality surveys were
conducted.
The objective of the longitudinal collection and analysis of phyto-
plankton was to identify the dominant algal genera along the river-estuar-
ine system during periods of high and low flow. The procedure used for the
phytoplankton surveys assumes that the two dates sampled represent typical
conditions in the river which may not be true due to meteorological events,
sporadic bloom conditions and large scale patchiness which can bias results
(3).
12
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At each station a single subsample was collected at each of five
surface sites oriented upstream, downstream and cross-channel from the
designated station site. Subsamples were pooled to a composite sample for
taxonomic analysis in order to compensate for small scale patchiness
inherent in single grab samples. This pooling of subsamples gave an
improved representation of species distribution in each region of the
river. Each of the five subsamples were split before pooling for analysis
of chlorophyll-a and pheophytin-a in order to provide an estimate of
original variability in the phytoplankton standing crop at each station
location.
Pooled composite samples were fixed immediately in the field with an
I-KI solution (4) and returned to the laboratory, and preserved by adding
formalin (2.5% final concentration). After 72 hours, the supernatant was
siphoned, and the residual concentrated by centrifugation before counting.
Chlorophyll samples (500 ml each) were immediately vacuum filtered through
0.45 um glass fiber filters, and filters placed in tubes containing a 1:1
mixture of 90% aqueous acetone and dimethyl sulfoxide (DMSO) stored on
vessel in an iced light-tight box, and returned to laboratory. This method
allows better extraction of chlorophyll from green algae.
In addition, at each station, temperature, salinity and dissolved
oxygen was measured with YSI Model 33 SCT meter and YSI Model 51B portable
dissolved oxygen water, calibrated using Winkler titrations. Light
penetration and extinction was measured using a standard 22 cm. Secchi disk
and a Li-Cor Quantum Radiometer/Photometer, Model LI-1928.
Analysis of chlorophyll-a was made after eluting filter pads with
acetone/DMSO at 4°C for 14 hours and analyzed according to SCOR/UNESCO
equations in Strickland and Parsons, (12) or if sample turbidity was high,
by the method described by Vollenweider (14).
Phytoplankton identification and enumeration was carried out on
aliquots from centrifuged sample concentrations using a Palmer-Maloney
nanoplankton cell with a Whipple occular counting grid at 400X resolution.
Replicates phytoplankton cell counts and toxonomic identification were made
on 10% of the samples.
Primary productivity measurements of photosynthesis and respiration
were made for this study by Biospherics Inc. at the stations shown in
Figure 2-4 using in-situ light and dark bottle methods and a dissolved
oxygen method modified from Vollenweider, 1974 (14). These measurements
were taken at the same time benthic respirometer measurements were made.
At each station, five water samples were taken at surface, 0.5, 1.0 and 2
meters and below the euphotic zone (less than 1% light penetration). The
upper four samples were used to construct the value for integral photosyn-
thesis from individual photosynthetic estimates. The subeuphotic zone
samples were used to estimate respiration at a station as well as serving
as blanks for the in-situ benthic water column respiration measurements.
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Each of the five samples at each depth were apportioned into triplicate
sets of light, dark and initial dissolved oxygen bottles, with the initial
bottles fixed according to the modified Winkler method but not acified
(15). The light and dark bottles were placed at their respective depth for
incubation of 6 hours. Surface bottles were evaluated for supersatuation
conditions. Dissolved oxygen analyses were carried out following acidifi-
cation using the method stated above in order to determine precision of
0.02 mg 02/liter. Data were expressed as photosynthetic oxygen change in
mg -at O2 hr~l. In addition to these measurements, water temper-
ature, dissolved oxygen, salinity, chlorophyll-^, light penetration/extinc-
tion, Secchi disc and pheophytin-a was assembled at the stations at various
depths. BOD5 was also taken from the three depths at each station to
coincide with the primary production sampling. The surface BOD sample was
taken from the surface productivity sample and the bottom aliquot taken
within 0.5 meters of the bottom and in nearby the in-situ benthic
respirometer chamber.
The University of Maryland collected water column phytoplankton photo-
synthesis and respiration data at the stations shown in Figure 2-5 for this
study. Estimates were made using the light and dark bottle technique
described previously. However, triplicate light bottles were suspended for
a shorter period (3 to 3.5 hours) at depths corresponding to approximately
90, 60 and 10 per surface insolation. One group of three dark bottles were
suspended at the 10% light level. Bottles were filled with surface water.
Triplicate bottles filled with surface water were also used to determine
initial dissolved oxygen concentrations. Gross primary productivity was
calculated by subtracting oxygen concentrations in the light and dark
bottles after incubation, and respiration calculated by subtraction of
initial and dark bottle oxygen concentrations. Apparent primary production
was determined as the difference between the initial bottle oxygen
concentration and light bottle oxygen concentrations, after incubation.
Areal estimates of water column photosynthesis and respiration were
calculated by plotting O2 concentration rates at the depth of incubation
and graphically integrating the area under the curve. Rates of respiration
were extended to the bottom or to the depth where surface insolation was
reduced to one percent (16).
Bacterial water and sediment analyses were performed at the locations
shown in Figure 2-4. At each station water samples were taken from near
surface and near bottom. An aliquot was withdrawn from the water sampler
into a 125 ml sterile bottle and composited.
Sediment samples were collected at each station shown in Figure 2-3
with a Ballchek 2 inch core sampler with a sterilized polyethylene liner,
and sub-sampled for bacterial analysis. Subsamples were made using the
upper sediment layer. The remainder of the sediment sample was divided
into two portions, one for wet seine particle size and silt/clay descrip-
tive analysis (i.e., seine through Taylor screen). The second subsample
was weighed, dried at 105°C, reweighed and combusted at 800°C in order
to determine moisture content and % organic matter.
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All bacterial samples were placed on Ice and analyzed within 10 hours
of collection. Standard methods of dilution plating (APHA, 14th ed.) was
followed. A selective medium was used to isolate and numerate total
Nitrobacter spp. separately from total Nitrosomonas spp. (American Type
Culture Collection (ATCC) medium #480 for Nitrobacter and ATCC medium #221
for Nitrosomonas), both prepared with 15 gram purified agar/liter for use
in plating. This method was used because viability of those organisms
belonging to each genus is directly determined by virtue of their growth on
the identifying medium and each viable organism produces a visible and
countable colony.
Benthic Measurement Methods
Sediment oxygen demand and nutrient fluxes were measured during this
study by the University of Maryland and Biospherics Inc. iBiospherics
monitored sediment oxygen demand at the locations shown in Figure 2-4.
These measurements were taken at the same stations, and dates, as the
primary productivity studies. Figure 2-6 is a diagram of the chambers
designed and used for this study. Chambers were placed firmly in the
sediment. The exposed sediment area of a chamber is 0.051 m^ (507cm^)
and the volume is 0.0076 m^ (7.6 liters) for a sediment to volume ratio
of 0.07. Imbedment and sealing between the chamber and sediment surface
was verified by scuba diver.
A dissolved oxygen meter (YSI model 51-B) and submersible probe with
stirrer was used to monitor oxygen depletion within the chamber. A battery
operated rheostat-controlled submersible pump with shipboard controls was
used to slowly circulate water over the sediment in order to approximate
natural river flow and uniform dissolved oxygen in the chamber.
The effect of respiratory activity by plankton and bacteria in the
chamber water was determined using data for the deepest primary productivi-
ty respiration estimate. The inset in Figure 2-6 indicates that only the
region of linear decrease of dissolved oxygen was used to estimate the area
oxygen demand since the curve becomes asymptotic under heavy respiratory
demand. Data were expressed as grams O2 m-^ hr~l. All oxygen probes
were calibrated using the modified Winkler method before deployment and
intercalibrated before leaving the laboratory.
The University of Maryland sampled stations shown in Figure 2-5.
Triplicate measurements of sediment nutrient flux and sediment oxygen
demand were made in-situ similar to the above description. Current
velocities in the chambers were maintained at approximately 10 cm/s
(typical of bottom current velocities). These chambers were fitted with
ports for extracting water for nutrient flux measurements. Oxygen
measurements were made every ten minutes for a period of 2 to 2.5 hours.
Nutrient samples were withdrawn at 20 minute intervals. A 10-liter dark
bottle filled with bottom water was incubated and sampled to estimate
nutrient-fluxes associated with the planktonic community.
15
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Nutrients analyzed for flux calculations were nitrate, nitrite,
ammonium, dissolved organic nitrogen, dissolved inorganic phosphorus,
dissolved organic phosphorus dissolved silicate and total phosphorus.
Samples were frozen and stored for analyses in the lab by methods shown in
Table 2-10.
Point Source Sampling Methods
Western Branch Haste Water Treatment Plant (station 750632) samples
were flow composited during each of the slack water surveys. Flow compos-
ited samples were accomplished by means of an ISCO 1870 recording flow
meter connected to an ISCO 1680 sampler equipped with a composite base. To
maintain the integrity of the flow composited sample, the sampling contain-
er was packed in ice during the collection period. To reduce the effects
of effluent chlorine a small amount of dechlorinating agent, 10 ml of
sodium thiosulfate, was added to the sample container. The water sample
from the treatment plant was collected immediately past the discharge weir
but before the water went into the conduit to the Western Branch tributary.
Due to the nature of the sample and the collection mechanism, analyses were
not completed for total chlorophyll-a, pheophytin-a and fecal coliforms.
Data was stored in ST0RET.
On June 22, 1981 samples were collected at sewage treatment plants in
the upper Patuxent River and analyzed for TKN, TP, Ortho-P,- NH3-N,
NO2+NO3-N and N02~N by the EPA, Central Regional Laboratory. This
data is not included in this report, but is available from the Tidewater
Administration.
Non-Point Source Assessment Methods
Five non-point source (HPS) sites were selected for monitoring and
analysis in the Patuxent River Watershed. Site selection was conducted in
cooperation with the local Soil Conservation District and Versar, Inc. The
subwatersheds were representative of the major land use and physiographic
features which affect the nature and extent of NPS pollution. Potential
subwatersheds were categorized according to the following considerations:
(a) Land use.
(b) Absence/presence of road crossings.
(c) Factors in the Universal Soil Loss Equation (rainfall, soil
erodibility, slope gradient, crop management, erosion control
practices)•
(d) Drainage area.
(e) Accessibility.
(f) Previous data.
16
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(g) The stream must be non-tidal at the sampling site.
(h) There must be no point source discharges upstream of the site.
(i) The stream channel must have a fairly regular cross-section or
existing flow control^structure to facilitate calibration of a
stage-discharge rating curve.
Three of the watersheds selected lie in the coastal plain province of
the river basin. The remaining two watersheds are located in the piedmont
province, specifically, within the Cattail Creek Basin of the Howard County
Soil Conservation District. Figure 6-1 shows the locations of these
subwatersheds.
The Patuxent River Park site is an entirely forested watershed which
has not been disturbed within the last 40-50 years.
Two agricultural watersheds near Route 258 in Deale, Maryland are
basins previously studied by the Smithsonian Institute, Chesapeake Bay
Center for Environmental Studies. Two years of NPS monitoring data exists
for these sites. These basins are mixed agricultural watersheds, the
predominant crops were corn and tobacco.
The other two NPS watersheds are in the Cattail Creek Basin of Howard
County. Cattail Creek was also identified by the Howard County Soil
District 208 planning program as a critical environmental area. These are
agricultural watersheds in the piedmont province of the Patuxent river
basin.
Stream Flow Measurements
A continuous flow record was maintained at each site. Stream flow
measuring techniques and devices varied depending on the characteristics of
the site. The methods included:
(a) The installation of primary flow control devices such as flumes
and V-notch weirs with empirical relations for measuring stream
flow.
(b) Existing structures, such as a drain culvert or a stable channel
section of a stream and subsequent calculation of the stage-
discharge rating curve. The stage-discharge relation of all
primary devices installed were also verified.
An H Flume was selected for use at the Patuxent River Park, Z-Farm and
G-Farm. H-type flumes are particularly suited for gaging runoff from small
agricultural or forested watersheds for the following reasons:
o Minimal head loss.
o Operate across a large range of flow conditions.
17
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o No stilling pond is created which could ultimately undercut the
structure due to back pressure.
o Operate with up to 50% submergence (ratio of downstream to
upstream head).
o Self cleaning, thus reducing the deposition of sediment within
or behind the structure.
Flumes were fabricated of sheet metal and installed at the sites
according to the specifications contained in the Manual of Agricultural
Hydrology, U.S.D.A. 1979 (17).
Installation of these flumes included approach boxes with extended
wingwalls. The flume was leveled and the crest elevation was tied to a
permanent benchmark by survey techniques.
Sharp crested 120° V-notch weirs with rectangular overflow were used
at sites where existing structures facilitated their installation and where
base flow was otherwise difficult to gage. The flow in the concrete box
culverts beneath Route 258 draining the Deale A and Deale B agricultural
watersheds were two such sites. The 120° V-notch increased base flow
sensitivity; however, it did not significantly reduce the culvert capacity.
When stormflow exceeded the notch capacity, the flow was gaged by rectangu-
lar overflow method. Support,for the weir plate was provided by the
culvert concrete apron and wingwalls. The notch was initially positioned
approximately 12 inches above the stream bed, however actual position
depended upon the characteristics of the nappe after the plate was
installed. The plate was raised to a point where the nappe experienced
freefall and is aerated on all sites. Although the secondary flow
monitoring instruments were factory calibrated according to the empirical
formula for the V-notch weir with rectangular overflow, the stage-discharge
relationship were checked periodically with actual current velocity
measurements.
Instrumentation
ISCO Model 1870 Flow Meters were used to continuously monitor stream
flow. These flow meters monitor stream depth using a pressure transducer
(bubble) system. The bubbler tube was submerged near the stream bed or
bottom of the flume. Air supplied by an internal compressor bubbles out of
the tube at a constant rate resulting in a pressure in the tube proportion-
al to the level in the stream. The flow rate was recorded on a strip chart
and total flow displayed. A chart speed of two inches per hour was used to
continuously record flow. The ISCO Model 1870 produces a signal propor-
tional to flow rate which allowed connection to automatic samplers to
collect a flow proportioned composite sample. An event mark was placed on
the chart record each time a stream sample was collected for the composite
storm sample.
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Water Sampling
In order to accurately monitor stormwater runoff, the collection of
flow proportioned samples was required and the flow measuring and sampling
instruments were designed to provide this capability. No extrapolation or
manipulation of the sample is therefore required after collection, and the
composite sample is analyzed to provide a mean concentration during a
storm.
The ISCO Model 1580 automatic sampler was coupled with an ISCO Model
1640W sample actuator for sampling. The sampler pumps uniform small
increments (at least 100 ml) into a single receptacle at flow proportioned
intervals. Actual sample size was determined on site and depended on the
volume and duration of anticipated runoff. The model 1640W sample actuator
initiated the sampling equipment when stream flow rose to a predetermined
height. Once sampling was initiated, the automatic sampler collected flow
incremented samples across the entire storm hydrograph and terminated
sampling when the stream height dropped below the actuator. Each time a
sample was collected for compositing, an event mark was placed on the flow
strip chart record mentioned above. This mark served dual purposes: (1)
the mark was used to corroborate the correct operation of the sampler. As
the water passed through the weirs and flumes, it ran into a mixing box and
pipe placed beneath the discharge nappe. A sampler intake tube was routed
to this box for the purpose of obtaining a well mixed sample,'thus avoiding
the problem of depth integration. The actual samples withdrawn were
composited with a 2 1/2 or 5-gallon polyethylene or borosilicate glass
bottle within the ISCO sampler.
While all NPS sites were equipped with monitoring instrumentation to
automatically begin sampling when runoff events occurred, the sites were
periodically verified by pre-runoff visits. Immediately before selected
storm events, field personnel visited each NPS site to insure that all
instruments were functioning properly, that the flow meter was calibrated,
and that the sampling action commenced when the stream stage rose to the
predetermined height. Site visits were also conducted during storm events
to verify that sampling had been initiated and to apply corrective measures
should the systems fail.
Located at each monitoring site an instrument housing was installed.
Each housing readily contained the flow meter, sampler, 12 volt batteries
(if used) tool storage and log books. The housing units were constructed
of steel to minimize the chance of damage and were weather-proofed. They
were securely mounted at the site with concrete fasteners attached to a
poured concrete foundation, or to wood posts which had been anchored to the
ground with concrete. Each housing had a case hardened padlock and hasp to
discourage vandalism. Weekly equipment maintenance visits also served as a
continuous check on the site security.
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Each NPS site was visited a minimum of once a week during NPS monitor-
ing even if no storm events occurred. During these visits, personnel
performed the following quality control checks:
(a) Strip chart removal and replacement;
(b) Calibration checks on time clocks and level recorders (i.e.,
adjustment of pen to correct stream level);
(c) Verification of instrument function and application of corrective
actions should they be required;
(d) Replacement of batteries where required;
(e) Documentation of equipment condition and recording of all required
adjustments.
During each site visit the field crew placed a mark on the hydrograph
just above the pen position. Time and date of visit were written near this
mark. The purpose of this was to provide a time check when the hydrographs
were later integrated for total storm flow calculation and to provide a
cross reference between the hydrograph and station log book in the event of
any question concerning the quality of data. Routine maintenance of flow
meters and samplers was performed monthly in accordance with the
manufacturer's recommendations.
Sample Collection and Shipment
Following each storm event or within 24 hours of sampling initiation,
(whichever came first), field personnel visited the NPS site for sample
collection. The time and date of visit was marked on the hydrograph strip
chart and in the log book maintained at each NPS station along with all
other relevant information such as name, volume of sample, temperature of
sample, etc. The sample container was removed and immediately split into
separate shipment containers as follows:
o Total Organic Carbon (TOC) - Borosilicate glass
o Solids/BOD - polyethylene
The samples were then placed in a cooler filled with ice. After all
samples had been collected and stored for shipment, they were immediately
delivered to the laboratory for analyses. Filtering and preservation of
samples in accordance with EPA approved procedures was performed by the
laboratory personnel as shown in Table 2-22 and Figure 2-7.
o Nutrients (TKN, NOjj,
polyethylene
20
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As previously mentioned, all samples were collected within 24 hours of
sampling initiation. This was required to insure that samples were
analyzed within required holding times. If the runoff event continued
after 24 hours the cycle was allowed to continue for an additional 24 hours
or until the stage dropped to the defined point. These additional samples
were analyzed separately from the first sample. Results were presented for
both the entire storm and separate 24 hour storm increments. Data and log
books are provided in an Appendix to this report.
Meteorological Assessment Methods
The objective of the meteorological assessment was the quantification
of the atmospheric conditions that directly or indirectly affected water-
shed chemical export. This assessment occurred concurrently with the NPS
sampling and included the monitoring of rainfall quantity and quality.
Atmospheric conditions, such as wind speed, temperature, relative humidity
and barometric pressure, which affected those loading rates for the entire
study area were recorded. To accomplish this goal a continuous recording
rain gage was placed at each non-point subwatershed under study. A weather
station, with the capability of continuously monitoring wind speed, temper-
ature, relative humidity and barometric pressure, located near the three
coastal plain sites was installed. Rainfall water quality information was
collected at the centralized weather station by adapting the rain gage
instrument to retain the measured rainfall for the purpose of chemical
analysis. Emphasis was directed towards the operation, calibration, and
maintenance of rainfall measuring instruments to ensure the overall quality
and quantity of rainfall data collected. Sites were instrumented with a
Weather Measure Model
Each rain gage station was visited a minimum of once a week, as well
as immediately following all storm events. At each visit instrument
functioning was verified. Because of the need for flow meter and rain gage
time synchronization, special attention was given to ensuring proper
function of rain gage clocks. All rain gages were synchronized, along with
flow meters, to a common time reference.
Each rain gage station was supplied with a field logbook for the
purpose of recording all site visits, instrument settings, malfunctions and
activities performed, as well as, any observations concerning land use
practices in the basin, which was relevant to the overall study effort
(e.g., fertilizing practices, plowing, etc.).
All instruments were strictly maintained according to the schedule
recommended by the manufacturer. This included occassional cleaning and
application of a silicone-oil to moving parts. Raingauge locations were
selected based upon the following factors:
o Centrally located to all the NPS study basins and not
necessarily central to the entire watershed since the
recorded data would be related to stormwater runoff
quantity and quality;
21
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o Because the instruments are extremely delicate the site
had to provide the maximum security possible.
o Accessibility.
o The site had to be on grass cover rather than hardtop
which could potentially cause excessive heat radiation
affecting instrument performance.
o The site had to be in a relatively open area with no
obstructions.
One weather station was located in the Patuxent River Basin study
area. The weather station provided an indication of the meteorological
condition in the Patuxent River study area which might impact atmospheric
NPS loading rates. The meteorological factors recorded included windspeed
and direction, relative humidity, ambient temperature and barometric
pressure.
The weather station was equipped with a field logbook to document all
activities that took place at the station during the course of study.
Instrument chart records were removed once a month. When chart records
were changed the following information was recorded at the end of the chart
roll:
o station number o date
o station location o field crew initials
o 'time (EST) o pertinent observations
o tape time (EST)
Bearings in wind speed and direction sensor were regularly checked and
replaced if necessary.
The weather station was equipped with a Weather Measure Model M701
Meteorograph which provided continuous record of ambient temperature,
relative humidity, and barometric pressure. A Weather Measure Model
W200-SC Wind Speed and Direction Sensor coupled with a Model W224 Series
recorder was also used.
The instruments were housed in an all wood instrument shelter which
complies with the U.S. Weather Bureau "cotton-region-type" shelter specifi-
cations. The shelter had louvered sides to allow free air circulation, and
a double roof to provide insulation from direct solar radiation as well as
rainfall. Wooden legs supported the shelter 48 inches above the ground
surface to further protect the instruments from surface radiation or other
conditions which may bias the operation of the measuring devices.
The weather station was visited for inspection on a weekly basis. At
each visit, instrument function was verified and corrective measures imple-
mented, should malfunction occur. As with the flow and rain gages, special
attention was given to ensure proper function of Instrument clicks.
22
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SECTION 3
LAND UTILIZATION, POPULATION AND WASTEWATER PROJECTIONS
Land Utilization
The Patuxent river basin experienced significant land use changes in
the late 1800's and early 1900's similar to eastern shore tributaries (18).
Figure 3-1 shows that since 1950 the Patuxent drainage area has experienced
a significant increase in land uses other than agricultural and forest
land. Forest land has decreased as well as pasture and cropland. If the
trends observed in Figure 3-1 continued, it can be estimated that by the
year 2000, fifty percent of the drainage area will be in non-agricultural
and forest land uses.
Population
Population of the Patuxent increased from 35,000 in 1940 to over
134,000 people in 1960. The 1980 population is estimated to be approxi-
mately 350,000. Figure 3-2 shows the population projections to the year
2020, developed in 1969 (19).
Figure 3-3 shows the county population projections developed by the
Maryland Department of State Planning (20). Table 3-1 shows the estimated
percent population increase within the Patuxent Basin counties from 1980 to
the year 2000. Table 3-2 shows, for comparison purposes, the approximate
difference between the 1969 projections and the reported 1980 population
for each county. From this table it can be seen that Howard County's
population was much larger in 1980 than projected. Several other county
populations were much lower than expected to have been by 1980.
In general, the 1969 projections overestimated the 1980 population.
Table 3-2 also shows that in 1969, the sewered population for 1980 was
expected to be around 375,000, or approximately 100 percent of the
population. As of 1982, the Maryland Department of State Planning
estimates that approximately 265,850 people, or 76% of the basin population
is served by central sewerage facilities.
Wastewater Projections
Table 3-3 shows the existing (1980) and projected year 2000 wastewater
flows in the basin by major facility (21).
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This table shows that the future waste flows may approximately double
by the year 2000. These figures also show that the per capita use of water
is approximately 100 gallons of water per day. Although the year 2000
population projections are not available at the time of this report, based
upon the 100 gallons per capita per day use of water and the 67.8 mgd
wastewater flows, sewerage capacity would be available for 677,613 people,
or a 51.7% increase in the Basin's sewered population for the year 2000,
assuming the same per capita use of water.
24
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SECTION 4
PHYSICAL CHARACTERISTICS OF THE PATUXENT RIVER
Geology, relief, soils, vegetation, rainfall and other variables
interact to create a river valley. The entire watershed drains approxi-
mately 900 square miles. The basin is approximately 80 miles long
(northwest to southeast) and is usually less than 15 miles wide, with a
total length of the river from headwaters to the Chesapeake Bay of
approximately 110 miles. The general flow of water is to the southeast
over Piedmont upland soils and rocks. The fall zone lies near the
convergence of Howard, Montgomery and Carroll counties at an elevation of
approximately 150 feet above sea level.
Geology
The topography in the Patuxent is influenced by the Piedmont and
Coastal Plain provinces. The basin has several unique upland areas under-
lain by metamorphic and igneous rocks providing a broadly undulating sur-
face with many deep river valleys, with smaller streams flowing over bed-
rock in the uplands area. Larger streams flow on a thin layer of alluvial
material, thus masking the valley cut into hard rock. In the lower coastal
plain portion of the basin, the streams and creeks flow in a much broader,
flat and densely vegetated floodplain underlain by alluvial deposits and
wetlands.
Below Hardesty, Maryland, the river becomes tidal and is long and
narrow, broken by swamps at various stream junctions. The upper part of
this area has been filled by deposition of eroded materials over the last
two to three hundred years.
Geomorphological Relations
Geomorphological relations have been developed to characterize the
Patuxent Estuary. In 1977-78 the Maryland Department of Natural Resources
conducted an extensive bathymetric survey of the river (23). Data from
this survey have been used to calculate geomorphological functions. In
addition, DNR topographic maps were used to determine the drainage area
relation. These sources of data were used to determine functions of drain-
age area, hydraulic depth, water surface area, width, cross-sectional area
and volume of the estuary.
25
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Hydraulic depth was calculated as follows:
DH = CA/TW (4-1)
where: CA = Cross-sectional area
TW = Water Surface Width
DH = Hydraulic depth
Water surface area was calculated from surface water widths and nautical
mile designations as follows:
Sk± = ((TWX + TW2)/2) * X12
(4-2)
where: TW^, TW2 = top widths at river nautical
mile 1 and 2 respectively
X12 = longitudinal distance between transect 1 and 2
,SA^ = Surface Area between transect 1 and 2
The volume of water between cross-sectional areas were calculated from
cross-sectional areas, and longitudinal nautical mile as follows:
= ((CA! + CA2)/2) * X12
(4-3 )
where: CA^, CA2 = cross-sectional area at transects
1 and 2 respectively
Vj = volume between transect 1 and 2
X^2 = longitudinal distance between transect 1 and 2
The BMDP statistical package was used to regress longitudinal values of
calculated surface areas, volumes, widths, hydraulic depth, and drainage
area. The following nonlinear functions were linearized and the above
geomorphological variables were regressed using least squares regression:
(a) y = MX 4C (4-4)
(b) y = K exp (ax), (4-5)
(c) x = K exp (ay) (4-6)
(d) y = K Xa (4-7)
In applying the above functions the dependent variable (Y) was the geo-
morphological variable and (x) was nautical mile. Each linearized function
was applied to the longitudinal river profiles of the variables and the
least squares regression giving the highest r2 (squared correlation
coefficient) was selected and is shown below:
TW = 4420.9063 exp (-0.07477X) r2 = 0.674 (4-8)
CA = 57641.6 exp (-0.12701X) r2 = 0.953 (4-9)
DH = 13.035 exp (-0.05224X) r2 = 0.5837 (4-10)
26
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SA = 4775455.9 exp (-0.07352X) r2 = 0.4789 (4-11)
DA = 0.66047X - 3.0492 r2 = .0562 (4-12)
V = 63211702 exp (-0.12973X) r2 = 0.806 (4-13)
These equations can be used to approximate the respective value a given
nautical mile with various degrees of confidence.
Cumulative functions of these variables were also determined for the
Patuxent Estuary by regression of the linearized functions listed above.
The advantage of developing cumulative functions of the morphological vari-
ables is that a smoother relation is observed, resulting in a much higher
r2 than the discrete step functions shown above. The second important
advantage of developing a cumulative variable versus river mile relation is
that the derived function can be differentiated with respect to river mile
to obtain an instantaneous variable function. For example, top width
calculated using the above function gives a 50% error at river mile 10.5.
The cumulative function gives an error of 21.6% at the same location. In
essence the cumulative function can then be used to approximate the value
of the variable at a particular nautical mile and at the same time can be
used to determine the rate of change of the variable between any two
transect or locations in the longitudinal direction. The best cumulative
geomorphological function for the previously described variables are:
CTW = (In X - 3.7203)/(-0.00003) r2 = 0.964 (4-14)
where:,} CTW = cumulative (surface) river
width at nautical mile X
CCA = (In x - 3.4760)/(-5 E -06) r2 = 0.968 (4-15)
where: CCA = cumulative cross-sectional
area at nautical mile X
CDH = (In x -3.8 499)/(-0.00854) r2 = 0.970 (4-16)
where: CDH = cumulative hydraulic depth at
nautical mile X
CSA = 9840331.9 (X ** 0.71896) r2 = 0.980 (4-17)
where: CSA = cumulative cross-sectional
area at nautical mile X
CDA = 1021.06 exp (-0.01921X) r2=0.941 (4-18)
CDA = cumulative drainage area at
nautical mile X
CV = (In x -0.28802)/(4.E -09) r2 = 0.968 (4-19)
CV = cumulative volume at river
mile X
Figure 4-1 shows the drainage area and cumulative drainage area;
Figure 4-2, the cross-sectional area and cumulative cross-sectional area;
Figure 4-3, width and cumulative surface water width; Figure 4-4, the
volume and cumulative volume; Figure 4-5, the surface area and cumulative
surface area; and Figure 4-6, the hydraulic depth and cumulative hydraulic
depth of the Patuxent estuary and lower tidal river, normalized to mean low
water datum.
27
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Freshwater Inflow
Freshwater Inflow to the mainstem of the Patuxent River during this
study period is shown in Figure 4-7. It can be seen that during the summer
and fall of 1980 freshwater input was lower than normal. The average cubic
feet/sec/sq. mile at Bowie during 1980 was 1.0142. The average for the
period of record for the Patuxent is 1.265 ft^/sec/sq. mile indicating
slightly below normal freshwater inflow. Figure 4-8 shows the average
monthly flows and standard deviation measured at Bowie with those obtained
during the 1980 study period.
Estuarine Hydrography
The Patuxent is a unidirectionally flowing freshwater river from the
headwaters to approximately Hardesty (64 nautical miles from mouth of
estuary). From this location to the mouth of the estuary the river is
subject to tidal influence. The Patuxent is a partially mixed estuary in
the lower portion of the river. Figure 4-9(b) shows the net non-tidal
transport of the estimated two layer flow system characteristic of the
Patuxent. Figure 4-9(a) indicates a potential three-layer flow system
observed by Owen, 1969 (24). Two 24 hour longitudinal velocity component
averages for the Patuxent are shown in Figure 4-10. Figure 4-10(a) also
indicates the potential three layer flow pattern in the lower river. This
diagram indicates the variability of the calculated surface of no net
motion.
Figure 4-ll(a) shows the net non-tidal current at Chesapeake Bay In-
stitute's station PX2 in 1952 and current meter moorings during this study
at PXl and PX2 (Figure 4-ll(b) and (c) respectively). Profiles a and b are
from the same station location area, and PX2 is upestuary in the Patuxent,
see Figure 4-12. Data collected in 1980 (25) for this study did not show a
three layer flow pattern when mean velocity profiles were calculated. A
comparison of the low-frequency component of the velocity measured in the
lower Patuxent estuary shows that the lower estuary responds in a classical
two-layer circulation, driven predominantly by the local winds. Comparison
of the axial component of the velocity record showed that when wind forces
the upper layer water to move up or down the estuary, the lower layer water
responds by flowing in the opposite direction, e.g., a classical two layer
flow. In order to determine the existence and variability of a three layer
flow system in the Patuxent, a greater time record of current measurements
in the Patuxent Estuary (25) is required.
Salinity data collected from the slack water surveys during 1980 and
1981 are shown in Figures 7-1, 7-2, and 7-3. Depth averaged values of
salinity were calculated at each station for each survey in order to deter-
mine the depth average salinity at a given nautical mile during the study
period. Least squares regression yielded two equations with relatively
high r-squares. The following polynomial form of an equation based upon
simple least squares procedure yields salinity as a function of nautical
28
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mile with the intercept of 16.717 taken as the average salinity observed
during the 1980-1981 study period at the mouth of the Patuxent:
Sx = -0.01664X1*9+16.717 (4-20)
Figure 4-13 shows the observed and calculated longitudinal salinity profile
using the above equation as well as an exponential function derived using
least squares. The polynomial function can be used for approximating the
percent of Chesapeake Bay water and Patuxent River freshwater at any
longitudinal location in the estuary using the relation:
Pv = F(Sx) (4-21)
So
where: P = percent freshwater or Chesapeake Bay water at nautical mile x
Sx = estimated or observed salinity at x
So = salinity at the mouth of the estuary
Figure 4-14 shows the results of this simple calculation, i.e. estimated
percent freshwater and Chesapeake Bay water from nautical mile zero to 45
using equations 4-19 and 4-20. This is based upon averaging data taken
from 1980-1981 and will change according to the input of freshwater. The
location of 50% mixing of these two water types occurs at approximately the
location of the mid-river sill.
Calculation of the flushing time of an estuary is useful in order to
approximate the time period a conservative pollutant may remain in an
estuary or estuary segment. The steady state depth averaged flushing time
of the Patuxent estuary for average freshwater inflow and mean flow
conditions can be approximated using the definition of the freshwater
flushing time (Tf) as follows:
Tf - Vf (4-22)
Qf
where: V = freshwater volume between transect X^ and X2
Qf = freshwater flow rate into the volume
This calculation does not include effects of tidal flushing which can be
important. Using volumes calculated from (a) the previously mentioned
bathymetric survey data; (b) the percent of a given volume of freshwater by
applying equation 4-20; and (c) determination of the freshwater input at a
longitudinal location calculated by applying equation 4-18, multiplied by
the average freshwater flow rate, the freshwater flushing time of the
Patuxent can be approximated, as shown in Figure 4-15. The total flushing
time obtained using this method is 315 days. Due to the assumptions of
depth averaged salinity, average freshwater inflow, mean low water volume
and no tidal effects, this value is more likely to be an approximation of
the maximum flushing time. „Q
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SECTION 5
SOURCES OF NITROGEN AND PHOSPHORUS TO THE PATUXENT RIVER
This section is a description of data collected from this study and
data gathered from other literature concerning the relative contribution of
nitrogen and phosphorus to the Patuxent River.
Point and Non-point Relative Contributions
Existing wastewater flows to the basin have been estimated to be 35
million gallons per day (mgd) Table 3-3. In the year 2000 wastewater flows
are estimated to be near 68 mgd (27). Existing point source loads to the
basin are estimated to be 861 tons/year total nitrogen and 373 tons/year
total phosphorus. By the year 2000, assuming secondary treatment level,
the loads would be 1,661 tons per year total nitrogen and 650 tons/year
total phosphorus. The basin non-point source potential loads in 1978 were
reported to be 816 tons of total nitrogen and 235 tons of total phosphorus
(27). By the year 2000, the potential NPS load was estimated to increase
to 985 tons/year TN and 240 tons/year TP. The Maryland Department of State
Planning recently reported that potential NPS loads of TN and TP may be
around 732 tons/year and 180 tons/year respectively (28). The limited data
collected from the 5 subwatersheds in this study indicated the potential
NPS load to the Patuxent may be as low as 282 tons/year TN and 101
tons/year total phosphorus during years of low rainfall. The latter
figures are calculated from data shown in Tables 6-28 and 6-29 of-this
report. These figures are low compared to other estimated NPS loads
reported. Calculation of NPS loads of TN and TP using the upper standard
deviation of the lb/acre/inch loading estimates from the 5 subwatersheds in
this study provides values in the range reported by Halka, 1982 (28).
Over the past 15 years environmental scientists have begun to consider
the role of precipitation and its components (e.g. acidity, sulfate,
nitrate, ammonia, and metallic,cations) to ecosystems (49, 50, 51, 52).
Correll and Ford (67) found for the Rhode River that the importance of
precipitation as a source of estuarine nitrogen was greatest when land
runoff was low and its nitrate concentration was also low, and in years of
drought or below average rainfall during the growing season. During this
study, limited data was collected concerning chemical concentrations of
nutrients in rainfall. Table 5-1 indicates loads of nitrogen and
phosphorus to the Patuxent River basin. Assuming 40 inches of rain per
year (29), those data indicate that total nitrogen (NO2 + NO3 + TKN)
loads from precipitation are 4.5X higher than TP loads.
30
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Nitrogen and Phosphorus Budgets
There are a number of potential sources of nitrogen and"phosphorus to
an estuarine system (i.e. fluvial, point and non-point source inputs,
intrusion of Bay waters, rainfall, water-column processes, and sediment
flux). During the last few years our perspective on the importance of
these components in estuarine productivity-nutrient cycling has changed.
For example, while water-column processes were once thought to dominate
estuarine N remineralization (53; 54), benthic remineralization is now
considered to be an important source of recycled nutrients available for
phytoplankton photosynthesis and as important zones of carbon and oxygen
consumption (55, 56, 57, 58). It seemed appropriate to calculate nitrogen
and phosphorus budgets for the Patuxent river in an effort to determine the
potential contribution of these nutrients from the sources discussed above.
Five nutrient budgets were calculated for the Patuxent River (Total
nitrogen, dissolved nitrite & nitrate, dissolved ammonia, total phosphorus
and dissolved orthophosphorus). These budgets assume 25 inches of rainfall
during a 7 month period (April through October, 1981). Sediment flux was
calculated by averaging benthic flux data taken for this study reported in
D'Elia, et.al., 1981 (16). Fluvial inputs were based upon 1981 average
concentrations and flows at station PXT0603 (Route 50) and at Western
Branch, for the upper and lower basins respectively. NPS loading rates
were developed from data reported in Section 6. Physical characteristics of
the basin such as drainage area, water surface area and estimated sediment
surface area were taken from data presented in Section 4. The rainfall
loading rates were calculate^ based upon data reported by Smullen et.al.,
1982 (29).
To calculate the exchange with the Chesapeake Bay a stratified two
layer flow condition was assumed at the mouth of the Patuxent River (i.e. a
net seaward flow at the surface and a net landward flow at the bottom).
Salinity was used as a conservative constituent to these flows.
(SB) (Qb) = (Of + Qb) (Sp) 5-1
where: Qp = fluvial flow (cfs)
Qg = Chesapeake Bay flow into Patuxent (cfs)
Sg = Average bottom salinity
Sp = Average surface salinity
The equation was rearranged to calculate the unknown flow coming in
from the Chesapeake Bay. The salinity values were taken from 1981 averages
at station XCF9575; 0.1 nautical miles from the mouth.
therefore: QB = Op Sp
(SB~Sp)
1981 averages of nitrogen and phosphorus concentrations at the surface
and bottom were multiplied by the corresponding flow to calculate the mass
loads.
31
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Three separate nitrogen budgets were computed and are shown in Figures
5-1, 5-2 and 5-3. Freshwater runoff from the mostly forested and urban
drainage basin supplies a major part of the nitrogen. For NO2 + NO3,
63% of the total load is from fluvial inflow. On the other hand, fluvial
inflow contributes only 17% of the total ammonia load. Ammonia's major
source is sediment flux. All three nitrogen budgets have an input source
contributed from the Chesapeake Bay.
A summary of the nitrogen budgets suggest that the bay and freshwater
inflow were major inputs to the Patuxent. The deposition of nitrate and
organic nitrogen to the sediment was recycled out as ammonia. There was a
lack of data concerning the benthic flux of dissolved organic nitrogen
(DON) in the lower estuary (16) and therefore the resulting calculations
were probably high for the average flux of total nitrogen from the lower
estuary sediment. Comparison of the total pounds of nitrogen loaded into
the Patuxent River to the pounds conserved (i.e. average concentrations)
suggests that the ecosystem utilizes 65% of the NO2+NO3, 92% of the
NH3 and 76% of the total nitrogen.
Two phosphorus budgets were calculated for the Patuxent. The
dissolved orthophosphorus (OP) budget and the total phosphorus (TP) budget
are presented in Figure 5-4 and 5-5 respectively. The fluvial discharge
contributed 66% of the TP with 23% of that being OP. The major source of
orthophosphorus was the sediment at 60%. Analysis of the phosphorus
budgets suggests that most of the fluvial TP sinks to the sediment as
particulate and is then released as orthophosphorus. The ecosystem used
86% of the total phosphorus inputed into the Patuxent and 88% of the
dissolved orthophosphorus.
It should be emphasized that the calculated NPS loads were low
compared to other studies, as stated earlier. This could have resulted in
lower calculations in pounds of nutrient loaded from fluvial discharge.
Significant loads of nutrients were inputed into the Patuxent River from
the Chesapeake Bay because of low rainfall and low flow conditions recorded
during this time period. Yet the hypothesis is the net exchange with the
Bay will stay near zero, implying that the Patuxent is an isolated system
which must utilize the nutrient loads within its' own ecosystem.
Complete budgets are rare for individual systems such as the Patuxent
due to problems inherent in their calculation. For example, biochemical
pathways involved in nitrogen and phosphorus cycling are unclear, various
nitrogen and phosphorus pool sizes are difficult to estimate, and flux
rates may vary seasonally. A better understanding of nitrogen and
phosphorus structure in sediments and nutrient fluxes to the Chesapeake Bay
are needed for more realistic budgets.
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SECTION 6
NON POINT SOURCE AND METEOROLOGICAL WATERSHED MONITORING
The following section describes the chemical export monitored from
five small subwatersheds within the Patuxent River Basin. Statistics were
used to describe the relationship of rainfall to chemical export or
non-point source loads. Measured data was used to estimate yearly loads
from the watershed. Comparisons were made to reported non-point source
loads by previous investigations. A description of the meterological
measurements taken during the study period is presented, along with a
general description of the soils In the Patuxent Basin.
Soils Description
The soils for the whole Patuxent River can be broadly divided into
those originating from igneous and metamorphic rocks of the Piedmont
Province and soils in the coastal plain derived from unconsolidated
sediments. Specifically, the Chester series of silt loams dominate the
upland Piedmont area. This series is deep and well drained, and underneath
this series is a deeply weathered zone of clays and silts derived from
weathering of original bedrock. Manor and Mt. Airy series occur on slopes
below the upland ridges and this series is found over phyllite and schists.
These soils are thin with rock fragments and mica flakes. The manor soils
have a danger of erosion due to the fact that they are well drained, and on
slopes. In the Patuxent, however, these soils are cultivated extensively.
The Mt. Airy soils are more restricted for use for pasture and woodland.
In the stream valleys, the Glenelg silt loams which are well drained soils
are found highest in the valleys near the break in slope between hillslope
and floodplain or terrace. Soils of this series have eroded, however they
are still highly productive and extensively cultivated. The flatter valley
slopes hold the Glenville and Bailie silt loam series, the Glenville series
being a combination of alluvial materials and derivation from schist.
These areas of the valley may have dense impermeable layers of the Bailie
series that hinder water movement within the soil, and are only moderately
productive. The Baile silt loams, formed in the floodplain and in the
upland depressions, are usually left in woodland.
The Glenelg-Glenville-Baille soils persist downstream in the valleys
until the stream develops a unique floodplain where overland flow occurs
with some regularity (within approximately a mile of the stream). Comus,
Codorus and Hatboro soils form in the alluvial materials washed from
hillslopes, and are typically found at the foot of slopes bordering the
floodplain.
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The sedimentary beds of the Coastal Plain province reflect an abrupt
change in composition, characterized by the Beltsville-Chillum-Croom asso-
ciation in the fall zone. Areas are underlain by red clays; mantles of
sand or silt (the Christiana loams and clays) and fine sandy sediments.
The Sassafras soils are widespread throughout this region in upland and
level terrain that is well drained and under extensive cultivation, as well
as residential and industrial use. The soils of the Coastal Plain valley
bottoms do not have a clear demarcation at the fall zone. South of the
fall zone, Comus soils associated with Codorus and Hatboro series occur in
the floodplains. These soils are frequently associated with areas of
flooding, recreational and wildlife reserve areas. Locally derived
alluvial deposits form members of the Bibb series in stream valleys. These
are deep silty or sandy loams that frequently show poor drainage due to
underlying clay layers, flat topography and a swampy environment. Much of
the drainage as in the Coastal Plain is swampy. Standing water may persist
in the floodplain a week or more after a rain. These areas form unique
habitat for various forms of wetlands wildlife (22).
Subwatershed Descriptions
Five watersheds were identified for monitoring chemical export during
storm events. Three of these watersheds lie in the Coastal Plain Province
and the other two watersheds are located in the Piedmont Province, partic-
ularly within the Cattail Creek Basin of the Howard County Soil Conserva-
tion District. Figure 6-1 indicates the location of the watersheds
monitored during this study. Table 6-1 indicates the landuse, size of the
watershed and the monitoring station number. The Patuxent Park site drains
into the Black Walnut Creek forested watershed. This site has not been
disturbed within the last 40-50 years, and thus serves as an excellent
reference for historical forested chemical export estimates. Access to
this site was granted by the Maryland National Capital Parks Commission.
The two agricultural watersheds on Route 258,-Deale, Maryland are basins
previously studied by Correll and Dixon, 1980, of the Smithsonian
Institute, Chesapeake Bay Center for Environmental Studies (32). Two years
of NPS monitoring data (1977-1978) existed at these sites and this program
thus continued data collection at these sites. These are mixed agricultur-
al watersheds. Predominant crops are corn and tobacco. Land use data and
physiographic characteristics of these sites has been previously reported
by the Smithsonian Institute.
The two Piedmont Province watersheds lie in the Cattail Creek water-
shed, and area indentified by the Howard County Soil Conservation District
208 planning program as a critical environmental watershed. These two
watersheds serve mixed agricultural (field corn and pasture) land uses.
Z-Farm is predominately made up of hydrologic soil group B soils and
G-Farm, hydrologic soil group A soils.
Z-Farm is approximately 55 acres in size, and the Howard County Soil
Conservation District (HCSCD) indicated that the 1981 crop year and land
uses were predominately a mixture of alfalfa, pasture, hay, grain corn,
silage corn and barley with a 1.3 acre homestead area. This site repre-
34
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sents a dairy operation, with convential tillage practices, drill planting
operations as well as no-till tillage. Figure 6-2 shows the soil map for
this site.
Table 6-2 shows the Soil Survey data and interpretations made by the
Howard Soil Conservation District (HSCD) for this site and the G-Farm
subwatershed (33). The Glenelg Soil series have a high soil moisture
capacity, are well drained and deep and strongly acid. If well managed
they are highly productive with the main limitation being soil erosion.
The native vegetation consists of mixed upland hardwoods, and the soils
form from weathering of crystalline rocks containing mica. The Glenville
series are moderately productive, moderately well drained, strong to
extremely acidic, have a fragipan and occur on flats, in depressions and at
the foot of slopes. They are formed from micaceous rocks and in alluvium,
with native vegetation of tolerant hardwoods. The fragipan impedes
drainage, limits the available moisture capacity and restricts root
developments. The Manor series consists of deep, well drained soils
located on level or steep uplands. They are formed from micaceous rocks
and mixed hardwoods are their natural vegetation. They have a thin surface
layer with soft rock fragments or gravel in some areas near the surface.
They have a high moisture capacity, acidic to very acid and are susceptible
to erosion. The Mt. Airy series are also moderately deep, strongly acidic
and excessively well drained soils whose native vegetation is mixed
hardwoods. They have a low to moderate capacity for soil moisture and
moderately productive. The depth to bedrock is approximately 30 inches and
the hazard of erosion is quite high.
Universal Soil Loss Equation (USLE) Factors were developed for these
two sites by the HSCD. Use of the factors for the G-Farm site (e.g. R=175,
K=0.26, LS = 1.67, L=200, S=0.09, P= 0.00, C=0.158) yielded a calculated
present loss of sediment at 9.6 ton/acre/year with T=2.75 ton/acre/year.
Application of the USLE to the Z-Farm site (e.g.'R=175, K=0.34, L=300,
S=0.06; LS=1.17, P=0.5 (strip cropping) C=0.07) yielded an estimated
present loss of sediment at 2.44 tons/acre/year with T=3.0
tons/acre/year.**
On the Z-Farm subwatershed hydrologic soil group B conditions were
good, with a total of 49.7 acres and hydrologic group A soils totalling 5.4
acres. G-Farm had 2 acres of hydrologic group C soils, 7 acres of group B
soils and 25 acres of group A soils. The average weighted watershed slope
was 9% for G-Farm and 6% for Z-Farm. The weighted SCS runoff curve number
for G farm was 61 and 70 for Z-Farm. Use of the Soil Conservation Service
peak discharge rate method, i.e. Technical Release 55, yield 35 cfs/inch of
runoff, an adjusted 39 cfs/inch of runoff and adjusted peak discharge of
29.8 cfs/inch of runoff at G-Farm. Table 6-3 shows the peak discharge for
**The sampling site was located within a pasture with cattle access which
probably disturbed sediment transport during storm events.
35
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various rainfall frequencies or storms for these two sites for comparative
purposes. Table 6-4 shows the detailed cropping or land utilization during
the 1981 sampling period for Z-Farm and G-Farm.
Figure 6-3 shows the general land use pattern obtained by the
Smithsonian Institute for the Deale A and Deale B sites and reported in
1978. Detailed land use analysis for these watersheds were not obtained,
compared to the excellent information obtained at the Z-Farm and G-Farm
sites. Table 6-5 indicates the exact location of the monitoring sites and
rainfall gauges.
Statistical Summary of Measured Chemical Export
A total of 116 samples were taken at the NPS stations; 102 were storms
and 14 were base flow. Of the total samples, 87 were from the agriculture
sites (77 storm, 10 base). Patuxent Park - 25 storms and 4 base flows;
Deale A - 31 storms and 3 base flows; Deale B - 24 storms and 4 base flows;
Z-Farm - 16 storms and 3 base flows; and G-Farm - 6 storm samples. Storm
loads were calculated by multiplying the resulting flow proportional con-
centration (mg/1) times the volume of water passing the flow measuring
device from the beginning of the storm to the end of the storm as deter-
mined by the stream hydrograph. The load was divided by the number of
acres yielding lb/acre for each monitored storm event. The average lb/acre
per storm event was calculated and the results
are shown in Table 6-6 thru 6-12.
Another simplistic approach for estimating chemical export is to
calculate the mass loading per acre during the storm, as indicated above,
and divide the load by the size of the storm event, i.e. inches of rain.
The resulting (lb/acre/inch) value can then be used to calculate estimated
loads from the monitored watersheds given seasonal rainfall estimates
and/or frequency of occurrence of storm events. Tables 6-13 thru 6-19
present the statistical sumc^aries of chemical export calculated in this
manner. The lb/acre/in mean value was used to estimate the lb/acre/year
export by multipying by 42 inches of rainfall per year. The results from
this calculation are shown in Tables 6-20 through 6-26.
The data collected during this study indicate that agricultural water-
shed chemical export is on the average three times greater than forested
areas (see Table 6-27). Specifically total suspended solids, representing
potential sediment transport from agricultural land is nearly five times
greater than forested land. The average water quality variable exports at
agricultural sites tend to be greater than forested areas by a factor of 2,
except nitrite. Total phosphorus chemical export from agricultural land
was approximately 6.8 times greater than the forested site. Total
Note: the average "C" factor for this crop year was eleva,ted abnormally
due to the farmers trial use of soybeans and sorghum following a
barley harvest.
36
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inorganic nitrogen is approximately 3 times higher for agricultural land.
Total organic carbon is greater by a factor around 2.5 and biochemical and
chemical oxygen demand is greater by a factor of 2.3 to 2.7. Total
dissolved nitrogen is approximately 1.1 to 1.3 times higher from agri-
cultural land than forested land assuming the sampling was representa-
tive. A comparison of data published from other chemical export studies
indicate that nitrate is generally higher from agricultural land, indi-
cating the Patuxent Park site may not be a typical site for nitrate export
measurements, however other nutrient parameter comparisons are similar to
ranges reported in the literature (34, 35). The nitrate (NO3) plus
nitrite (NO2) comparison indicates the total nitrite plus nitrate export
is probably representative. It is believed that the NO2 values are not
representative but NO2+NO3 observations are valid.
Comparison of Estimated Storm Loads from the Patuxent River
The statistical summary of data presented in the previous subsection
and reported published literature was used to estimate potential chemical
export from the Patuxent River Basin surface to waters during storm events.
Table 6-28 shows the potential watershed export of total phosphorus to the
river during storm events using the loading rates developed from this study
for forested and agricultural land. The total estimated potential load of
total phosphorus from agricultural land utilization is 532,813 lbs/year.
Approximately 104,131 lbs/year from forested land. This table also indi-
cates the potential load from other land uses of 37,574 lbs/year of total
phosphorus. These estimates indicate agricultural land contributes 79% of
the NPS load, 15% from forested land and approximately 6% from other land
uses. Other researchers and agencies have shown similar trends (28).
Table 6-29 shows the estimated potential total nitrogen from loading
rates developed from this study. These sites indicate total nitrogen of
approximately 654,962 lbs/year from agricultural land or 30% of the esti-
mated total and 12% from forested land. Data developed by the Maryland
Department of State Planning (28) indicate that other land uses contribute
328,287 lb/year of total nitrogen or approximately 58% of the total nitro-
gen load. It should be noted that these are estimated from the average
loading rate discussed in the previous subsection and may be low.
Calculation of the total nitrogen loading using the upper range of the
standard deviation of the mean total nitrogen loading rate (6.9297) for all
agricultural sites monitored in this study indicates agricultural lands may
contribute around 1,425,737 lbs/year of total nitrogen. Use of the upper
range of the agricultural loading rate indicates, from data in this study,
that agricultural land may indeed contribute approximately 71% of the total
nitrogen from the land surface to the river system and thus 13% from
forested areas and 16% from other land uses. This latter estimate using
data solely from the Patuxent River Basin indicates agricultural loads of
total nitrogen are close to other estimates (28).
37
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Total organic carbon from agricultural land use, using a loading
factor of 25.779 lb/acre/year indicates an estimated 5,303,849 lbs/year.
Forested land may contribute on the order of 2,754,899 lb/year, with a
loading rate of 10.1009 lb/acre/year.
Rainfall Runoff Statistical Relationships
Least square linear regression was applied to chemical export data
from the five subwatersheds monitored for this study. Regressions were
performed using the lb/acre/inch of rain (dependent varible) and stream
flow in gallons (independent variable) from the storm event monitored at
each site and all sites combined. Logarithmic transformations were
performed on the dependent and independent variables above, and the
resulting best regression equation was selected based on the regression
coefficient (r). These equations are shown in Table 6-30.
Least square regression was also applied to lbs/acre (dependent
variable) chemical export versus total rainfall and various linear com-
binations of total storm rainfall and average or maximum storm intensity.
Logarithmic transformations were also performed on the dependent and
independent variables and the best regression equation was selected based
on the regression coefficient (r). The results of this analysis are shown
in Table 6-31.
Regressions were also performed with lb/acre chemical export (depend-
ent variable) versus flow in gallons and combinations of factors which
normalized storm flow to size of watershed (acres), total inches of
rainfall and maximum intensity of rainfall during the storm. Logarithmic
transformations were made on dependent and independent variables. The
results of this regression analysis is presented in Table 6-32 showing the
selected regression equation based upon the highest regression coefficient
(r).
Comparison of these least squares regression results indicate that
BOD5 and BOD30 is strongly dependent upon storm flow at each site.
Highest regression coefficients were obtained by combining data from all
sites and normalizing flow to the size of the storm, i.e. total rainfall.
Total suspended solids (TSS) correlations were generally higher when
lb/acre was regressed against flow. TSS versus total rainfall times maximum
storm intensity (TRF*M1NT = dependent variable) was greatest at the Z-Farm
watershed, indicating rainfall processes affected chemical export more than
stream transport processes from this site. Nitrate plus nitrite (lb/acre)
regression indicates very good correlations with increased flows. The same
is true for ammonia, with the Deale B site yielding the highest coeffi-
cient. TKN and dissolved TKN show good correlations. It is interesting to
note that gallons normalized to the size of the storm may be a better
predictor of total phosphorus at Deale A.. All other variables were highly
correlated to stream-flow as expected.
38
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Multivariate regression techniques were applied to the data collected
from these sites. It was not uncommon for squared multiple correlations
above 0.9 (see table 6-33 and 6-34). Although discrete sampling over a
hydrograph or storm may yield excellent detailed storm characterization,
the lb/acre versus flow or stage correlations obtained from flow-composite
sampling as conducted in this study provide excellent data for estimating
storm loads. The results of the multiple regression (i.e. high r^)
analyses also Indicates that calibration of hydrological simulation models
at these sites will probably yield excellent loading information, especial-
ly at the Deale A, Deale B and Patuxent Park Watersheds. Due to limited
sample collection at the G-Farm site and Z-Farm site, and associated lower
correlations, the confidence of results from a hydrologic simulation model
will be less.
The Howard County Soil Conservation District estimated the existing
soil loss with the Universal Soil Loss Equation (USLE) on Z-Farm and G-Farm
subwatersheds. Using their results and the monitoring results one can
calculate a potential gross sediment delivery rate for use with the USLE.
The estimated average sediment delivery ratio at Z-Farm is estimated to be
14.6E-03 with a maximum of 42.3E-03 and estimated minimum of 4.84E-03. At
G-Farm, an average of 22.IE-03 a maximum of 44.9 E-03 and minimum sediment
delivery ratio of 20.9E-03 is indicated.
Meteorological/Rainfall Analysis
Bulk precipitation measurements were made from the Patuxent Park
subwatershed. Concentrations were measured from 26 storms and the data are
shown in Tables 6-35, 6-36, 6-37 and 6-38 along with the size of the
rainfall event in centimeters of rain. Loading rates calculated from this
data are as follows: TOC=30.59 kg/ha/inch of rain; N02+N0"3=137.952E-3
kg/ha/inch of rain; TKN=359.229E-3 kg/ha/inch of rain; and TP=36.836E-3
kg/ha/inch of rain.
Storm analysis indicate that at the five subwatersheds monitored for
chemical export, no storm was larger than the 1 year storm or with a
probability of occurrence less than 100%. This indicates quite clearly
that storm runoff monitored during this study represents average size
storms. The largest storm where quality data was taken from the subwater-
sheds was 2.48 inches. Based upon rainfall frequency data, a one year
storm (100% probability of occurrence) is equal to 2.6 inches of rainfall;
a 2 year storm (50%) is 3.2 inches; a 5 year storm (20%) is 4.2 inches; a
10 year storm (10%) is 5.1 inches; a 25 year storm (4%) is 5.6 inches; a 50
year storm (2%) is 6.3 inches; and a 100 year storm (1% chance or probabil-
ity of occurrence) is equal to 7.2 inches of rainfall.
39
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SECTION 7
DESCRIPTION OF LONGITUDINAL SLACK SURVEY RESULTS
The following is a description of the results of slack water surveys.
Seventeen slack water surveys were conducted from 6-25-80 to 8-13-81 as
described in Section 2.
Slack tide salinity profiles are shown in Figures 7-1 and 7-2. The
extent of the idealized salt wedge and the expected area of the turbidity
maximum region can be seen in these Figures. These depth averaged salinity
profiles show that the salinity wedge decreases to nondetectability between
nautical mile 30-40. Stratification was dominant in the lower and mid
estuary stations, with the bottom layer being more saline. Occasionally an
inversion occurs which causes the surface layer to have higher salt concen-
trations as seen on 3-19-81, 6-25-81 and 7-28-81. Around nautical mile 15
to 20 the extent of vertical stratification decreases substantially in
almost all slack survey as shown in plots in Figure 7-3. Table 7-1 shows
the salinity statistics for the slack surveys. Average salinity in the
river observed during this study was 10.32 ppt. The increase in salinity
observed throughout the river from June 1980 to July 1981 is due to the
below average rainfall during the study period. Comparing the slack survey
salinity results to historical data indicates that, on the whole, the
salinity levels are low. Historical data of salinity at the mouth of the
estuary yield a mean of 20.7 ppt + 6.5 ppt. Data collected during this
study period ranged between 10.5 to 20 ppt with an average of approximately
16.4 ppt at the mouth of the estuary.
Temperature profiles are presented in Figure 7-4. The largest surface
to bottom temperature differences are observed in the lower estuary as
expected. Differences between the upper and lower layers increased in late
spring, to their maximum in June and July and decreased again in August.
Average temperatures for the river were 20.9 + 6.7°C with minimum and
maximum values of 4 and 33.1°C respectively.
Figure 7-5 shows longitudinal values of pH. Values higher than 8 were
observed at mid-river in July 1980 and in the lower estuary in April and
June 1981. The lowest values were observed mid-river in August, 1980 and
in the upper river in September 1980, approaching a pH of 6 between
nautical miles 35 to 52. Average pH observed during the study period was
7.4 + 0.56 with a minimum of 6.1 and a maximum of 9.4. The March, 1981
values are critical since these upstream values may not be conducive to the
success of spawning finfish. Further evaluation of pH in the river may be
40
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warranted In order to determine the extent and duration of any pH problem
tn the estuary, especially during the spring during and after the spawning
period of fish.
Figure 7—5 plots show the results of Secchi disc measurements. These
values indicate that in the expected turbidity maximum region the light
penetration reaches an average minimum of 0.1 meters. The July 1980 survey
indicated that a substantial area in the river received very little light
penetration as measured by secchi disc. Phytoplankton and related measure-
ments taken at approximately the same time and location showed a very heavy
inorganic detritus load as well as the largest number of species of phyto-
plankton and total cells/ml of water. Diatoms and Blue Greens were the
dominant species in this region followed by total Cryptophytes and Cryso-
phytes. Also during this survey, the highest water temperatures were
observed and pH above 8 was observed in this region of low secchi measure-
ments. Dissolved oxygen was below 4 mg/1 and up to 8 mg/1 with associated
DO saturation from 45% to 100%. Additional observations could be made
concerning other nutrient parameters, however the above observations are
made to show how secchi disc can be a good indicater of phytoplankton
blooms and high organic and detrltal concentrations in ambient estuarine
water.
The Dissolved oxygen plots shown in Figure 7-7 indicate, as expected,
greater surface to bottom differences in the lower river, especially during
the July 21, 1980 survey, at which time dissolved oxygen at the bottom of
the lower estuary was approximately 1-2 mg/1. It is interesting to note
that during every slack, survey the surface to bottom variation at the
station (XCF9575) nearest the Chesapeake Bay was not as stratified as
expected. During several surveys in the summer and early fall months,
there was very little stratification. In several surveys increased DO was
observed in the turbidity maximum area relative to upstream and downstream
values. This phenomena is probably related to the greater primary
productivity and mixing phenomena. Average river DO during 1980 and 1981
was 7.5 + 2.61 and 7.09 + 2.45 mg/1 respectively. Average mid-depth DO at
upriver stations was 6.54 + 1.55 and 7.19 + 2.44 mg/1 during 1981 and 1980
respectively. Lower river bottom DO averaged 7.22 + 2.87 and 6.91 + 2.89
mg/1 during 1980 and 1981 respectively.
Figure 7-8 shows the calculated dissolved oxygen saturation (DOS)
profiles for the slack water surveys. During June and July of 1980 super-
saturation of dissolved oxygen was observed. Supersaturated waters are
observed mid-river in September and November of 1980, however stratifica-
tion is lower. 1980 and 1981 slack survey data indicate average DOS of
82.9 + 21.1% and 79 + 19.7% respectively. Mid-depth samples taken at the
upper river stations indicate lower than average DOS 72.6+14.7 in 1980
and 69.6 + 12.9 in 1981. D.O. saturation during the study period ranged
from 5 to 146%.
Slack tide longitudinal profiles of dissolved nitrate are shown in
Figure 7-9. As expected, concentrations are higher up river, especially
above mile 35 where salinity is not detected. Decreasing lower river
concentrations are probably due to dilution of freshwater with Chesapeake
41
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Bay water, although a potential mid-river source is indicated by an upper
river peak on occassions. This peak is at the station below Western
Branch. Highest concentrations in the upper river were observed during the
August, September and October 1980 surveys, when rainfall had been minimal
for several months. Average nitrate for the river during the study period
was 0.61 + 1.04 mg/1. Nitrate values at the upper river, mid-depth
stations yield a 1980 and 1981 mean and standard deviation of 2.64 + 0.82
and 2.24 + 0.49 mg/1 respectively. Very little stratification was observed
in the longitudinal profile. Estuarlne bottom depth observations indicate
a mean of 0.21 + 0.38 and 0.56 + 1.94 mg/1 for 1980 and 1981 respectively.
Surface observations in the estuary indicated a mean of 0.21 + 0.39 mg/1
for 1980 and 0.47 + 0.94 mg/1 in 1981.
Figure 7-10 shows low concentrations of dissolved nitrite as expected
during the longitudinal slack surveys. Similar to nitrate, nitrite is
higher In the upper tidal river section. In several cases a mid-river peak
of NO3 is observed, indicating a potential source in the vicinity of
Western Branch and the turbidity maximum area of the river. As was also
noticed for nitrate (NO3), there were very low measurements for nitrite
(NO2) In the lower estuary. The exception occurred on August 20, 1980
when nitrite had increased concentrations and stratification in the lower
estuary. Mid-depth samples taken at the upper river stations indicate an
average of 0.14 + 0.12 and 0.15 + 0.08 mg/1 during 1980 and 1981. Surface
values in the estuary are much lower, i.e., 0.01 + 0.02 mg/1 in 1980 and
1981. Bottom mean values were highest in 1980 (0.2 + 0.02 mg/1). In 1981
the bottom water average was 0.02 + 0.02 mg/1.
Longitudinal plots of dissolved ammonia shown in Figure 7-11 also
indicate higher upper river mid-depth concentrations. These figures as
well as statistical analyses indicate that bottom waters on many occasions
are higher than surface values as expected. A mid-river source or peak
concentration is observed on several occasions in the upper estuary.
Stratification of ammonia is greater than observed stratification of NO2
or NO3, probably due to sediment flux of ammonia to the water column. On
several occasions these plots indicate concentrations at the mouth of the
estuary are higher than the lower estuary, indicating the intrusion of Bay
water as a source of ammonia to the lower estuary. Bottom average values
during 1980 and 1981 were 0.10 + .19 and 0.13 + 0.19 mg/1 respectively.
Concentrations are generally lower at the surface as expected, with 0.06 +
0.09 and 0.12 + .20 as the average concentrations during 1980 and 1981.
Mid-depth values at the upper river stations averaged 0.63 + 0.63 in 1980
and 0.59 + 0.48 in 1981. All data for intensive and slack surveys indicate
surface and bottom values differ by an average of 0.03 mg/1 ammonia.
Total particulate nitrogen (TPN) concentrations observed during the
slack surveys (Figure 7-12) do not indicate consistently higher concentra-
tions at mid—depth stations in the upper river. In fact, in all but one
survey TPN concentrations are higher in the middle portion of the estuary
where relative flushing time is greatest. These concentrations are
representative of nitrogen fixed in organic material and with primary
producers and as such indicate high densities of algal cells. TPN
42
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concentrations near 0.9 mg/l occur quite often in the estuary. During
August 20, 1980 TPN in the middle estuarine zone exceeded 3 mg/l. As
expected, surface TPN is usually higher but there is not a consistent
trend. TPN during several surveys are higher at the surface and bottom
depths near the mouth of the estuary, indicating a potential source.
Figure 7-13 shows the dissolved kjeldahl nitrogen measured during the
1980-81 study period. Upper river stations indicate higher concentrations.
These concentrations reflect the ammonia and organic nitrogen forms in the
river. No consistent trend is observable in the estuarine zone except that
it is not uncommon for maximum concentrations to shift between bottom and
surface waters.
Figure 7-14 shows the dissolved organic nitrogen values. These values
provide insight into the river in that concentrations of dissolved organic
nitrogen are much lower, on the average, in the upper tidal river. This
indicates that either the Chesapeake Bay is a source of organic nitrogen or
that other Inorganic nitrogen is being utilized to produce living organic
matter, whose composition is made of organic nitrogen. Since Chesapeake
Bay waters are not consistently higher in TON at the mouth of the river,
it could be easily concluded that the lower and middle estuary is a very
productive portion of the estuary for conversion of organic nitrogen to
inorganic nitrogen. This hypothesis is substantiated by a review of TPN
concentrations in the middle and lower rivers where it can be seen that the
TPN peak concentrations are associated with TON peak concentrations. The
dissolved organic nitrogen peaks could be a result of high cell densities
of primary producers smaller than 0.45 um. In fact, the July 21, 1980
concentration profile follows the same trend of increasing numbers of total
phytoplankton cells/ml observed during the same time period, and the
general trend of cells/ml of unidentified 1.5-2 um coccoid species.
Total organic carbon was only analyzed for the first five survey dates
(June 25, July 21, July 28, August 20 and September 15, 1980). The highest
TOC value occurred on August' 20, 1980 when total particulate nitrogen was
at its maximum, at the surface, during the study period. At this same time
DO stratification was greatest at the same location during the survey with
surface DO near 8 mg/l and bottom DO near 4 mg/l. The pH ranged from 8 at
the surface to 6.6 at bottom depth. At the same time, salinity was
observed to be greater at the surface, and surface temperature was lower,
indicating upwelling of potentially nutrient rich waters (Figure 7-15).
Total particulate phosphorus was also high at this region where mixing
of fresh and salt water is expected to be greatest (see Figure 4-14) and as
seen by a peak in relative retention time (see Figure 4-15). Nitrogen (in
the forms of nitrate, nitrite and ammonia) does not show a peak in this
portion of the river, but dissolved phosphorus does, indicating that
phosphorus adheres to the suspended solids. Ortho-phosphorus and ammonia
show a general trend of higher concentrations at the stations where the
turbidity maximum is, supported by high pheophytin-ji concentrations. More
interesting is the fact that the longitudinal plot of silica has a minimum
where the peak TOC occurs.
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Plots shown In Ftgure 7-16 show the concentrations of total phosphorus
observed during the slack surveys, with higher concentrations In the head-
waters as expected. Mid-river peaks of total phosphorus values were
observed Indicating a source upstream potentially due to biological
conditions and/or due to mixing in the turbidity maximum area of the river.
Average total phosphorus values at the surface and bottom depths were
approximately the same on the average. 1980 and 1981 surface total
phosphorus values were 0.10 mg/1 and 0.11 mg/1 respectively. Bottom depth
total phosphorus values averaged 0.10 mg/1 and 0.13 mg/1. Mid-depth
stations in the upper river showed a mean and standard deviation of 0.41 +
.32 mg/1 and 0.28 + .18 mg/1 in 1980 and 1981 respectively. Higher
concentrations up river in 1980 are probably due to relatively constant
point source inputs and groundwater recharge during this low flow period.
Total particulate phosphorus survey plots, shown in Figure 7-17 follow
a general trend of decreasing concentrations from the headwaters to the
mouth of the estuary. During several of the surveys a distinct mid-river
peak of TPP was measured. This peak occurs in the vicinity of nautical
miles 23-35, an area of the expected turbidity maximum and where bottom
topography (see Figure 4-9) would indicate potential upwelling of Chesa-
peake Bay water and associated particulate matter. This peak may occur due
to tidal forcing functions and high freshwater inflows which probably
resuspend particulate organic matter and associated nutrients. Bottom TPP
concentrations are generally higher throughout the river. Higher concen-
trations at the mouth of the estuary do not necessarily indicate the
Chesapeake Bay as a potential source of total particulate phosphorus.
Figure 7-18 plots of dissolved total phosphorus, during slack surveys,
indicate higher upstream concentrations. Concentrations at the mouth of
the estuary do not indicate Chesapeake Bay waters as a source of dissolved
phosphorus. Mid-estuary maximum concentrations were detected on several
surveys in the vicinity of the turbidity maximum where upwelling of bottom
waters potentially rich in dissolved phosphorus would be expected to occur.
Surface concentrations of dissolved phosphorus were, on the average,
slightly higher than bottom waters by 0.01 mg/1 during 1980 and 1981.
Great stratification of dissolved phosphorus is observed usually in the
mid-estuary. Average upstream mid-depth values during 1980 and 1981 were
0.41 + 0.32 and 0.28 + 0.18 mg/1 respectively. Average up river mid-depth
concentrations were higher in 1980 by 0.13 mg/1, probably due to decreased
rainfall during 1980. Bottom depth concentration average and standard
deviation during 1980 and 1981 were 0.03 + 0.02 and 0.02 + 0.02 mg/1
respectively. Average surface concentrations were 0.03 + 0.02 mg/1 in 1980
and 0.02 + 0.02 mg/1 in 1981.
Dissolved ortho-phosphorus trends were similar to dissolved phosphorus
concentrations (see plots in Figure 7-19). Concentrations decrease down-
stream and only show occasional higher concentrations at the mouth of the
estuary, with a general trend of increasing values in the mid-estuarlne
zone. Stratification was not observed often. Surface and bottom concen-
trations show identical average values of 0.02 + 0.02 mg/1 in 1980 and
44
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1981. Again, mid-depth samples taken up river indicate higher average
concentrations in 1980 (0.44 + 0.32 mg/1) and lower concentrations in 1981
(0.27 +0.18 mg/l) or concentrations In 1980 were higher, on the average,
by 0.17 mg/l. Thus, it is apparent that during low flow conditions,
ortho-phosphorus Increases more than total or dissolved phosphorus
concentrations. This could be critical for the river since ortho-phos-
phorus is the form of phosphorus readily used by primary producers.
The slack tide profile of total nitrogen to phosphorus ratios are
shown in Figure 7-20. In almost all slack water survey plots there is a
trend for phosphorus limitation at the mouth of the estuary. At approxi-
mately nautical mile 16 the data indicates a trend of nitrogen limitation.
The system shifts again towards phosphorus limitation in the turbidity
maximum area of the river where productivity was highest. The upper river
then appears to shift again towards a nitrogen limited environment. A
mid-river peak in concentrations was observed during several slack water
surveys. A more detailed analysis of these profiles, described later,
indicates an association of total N-P longitudinal profiles to antecedent
rainfall-runoff events. Figure 7-21 shows longitudinal plots of the
redfleld ratio (dissolved NH^ + NO^ + NO-j divided by dissolved
ortho-phorphorus). Similar to the total N:P ratio the Redfleld ratio has a
mld-estuary peak in the area of the turbidity maximum. The September 1980
survey did not show such a pronounced peak. This survey had very low N:P
Redfield ratios throughout the longitudinal profile, indicating for that
day the river was entirely nitrogen limited. The survey was conducted more
than thirty days after the last storm event as evidenced through examina-
tion of the Route 50 USGS gauging station hydrograph record. The low flow
conditions caused a depletion in orthophosphorus suggesting Its source is
from freshwater inflow.
Longitudinal plots of BOD^ are shown in Figure 7-22 and show that
surface BOD is higher during most of the study period. Surface BOD5
average and standard deviation was 3.32 mg/l in 1980 and 3.18 mg/l in 1981.
Bottom depth BOD^ was 1.93 mg/l in 1980 and 2.49 mg/l in 1981. Strati-
fication was more pronounced in the summer. Mid-depth upper river samples
showed slightly higher average values of 3.35 mg/l in 1980 and 3.71 mg/l in
1981. Minimum B0D5 observed during the study period was approximately
zero (0.1) and a maximum of around 10 (10.6). The longitudinal trends
generally show peak values occurring In the mid estuary between 16-35
nautical miles. Comparison of BOD values during periods when phytoplankton
blooms were thought to have occurred shows a relatively good correlation.
During most surveys a mid-river peak in the turbidity maximum region was
observed.
Limited chemical oxygen demand measurements were observed during a few
surveys and results are plotted in Figure 7-23.
Chlorophyll-a plots are shown in Figure 7-24. It can be seen that
chlorophyll-ja values are almost always low in the upper river. Mid-depth
upper river values indicate average and standard deviation of 14.83 + 17.8
45
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ug/1 and 20.72 + 19.34 ug/1 during 1980 and 1981 respectively (uncorrected
for presence of pheophytin); 11.96 + 15.62 ug/1 in 1981, corrected for
presence of pheophytin. Surface values averaged 30.92 + 60.58 ug/1 in 1980
and 26.72 + 17.2 ug/1 in 1981 (uncorrected). Bottom depth chlorophylls
averaged 11.71 + 13.57 ug/1 in 1980 and 22.40 in 20.40 in 1981 (uncorrect-
ed). Corrected values at the surface indicated an average of 20.42 + 15.15
in 1981 and 11.96 + 15.62 at bottom depths in 1981. Mid-river peaks are
apparent in the turbidity maximum area and lower regions of the estuary.
Pheophytin-a values for 1980-1981 indicated mid-estuary peaks in
bottom waters throughout the study period. The upper two stations indicate
a reduction of concentration due to dilution. Most of the time, however,
at river miles 23-35 there is a consistent peak in concentrations (in the
turbidity maximum area). Values were higher, in general, in 1981, with a
mean of 9.5 and standard deviation of 16 ug/1. Bottom water concentrations
in 1980 were 5.52 + 5.38 ug/1. Surface values averaged 4.1 + 13.4 ug/1 in
1980 and 5.8 + 7.6 in 1981. Mid-depth upper river samples averaged 4.72 +
3.87 ug/1 in 1980 and 5.52 + 5.6 ug/1 in 1981. During the study period
pheophytin ranged from zero to 100 ug/1 (see Figure 7-25 plots).
Figure 7—26 shows dissolved reactive silicate. It can be seen that
concentrations decrease until mile 35 in all but four surveys. During
these surveys the decrease is not at substantial in the turbidity maximum
region. In almost all surveys there is a lower river peak in silica
concentrations. Silica concentrations were higher at the mid-depth tidal
river stations (1980 - 4.3 + 2.15 mg/1; 1981 - 2.82 mg/l). Lower estuary
samples averaged 4.30 + 2.15 mg/1 at the surface and 4.77 +2.7 mg/1 in
bottom waters in 1980 and 3.31 +2.82 and 3.58 + 3.27 mg/1 in surface and
bottom waters in 1981.
Seston or total nonfilterable residue longitudinal plots (Figure 7.27)
indicate peak mid-river concentrations in the region of the turbidity
maximum. In some cases two peaks are observed in the river which may
reflect phytoplankton blooms. As expected, residue is higher in bottom
waters (1980 - 40.78 +34.18 mg/1; 1981 - 61.04 +82.71 mg/1) and surface
and mid-depth samples were approximately the same on the average (Surface:
80 - 34.27 + 17.91 mg/1; 1981 - 34.27 + 17.91 mg/1 Mid-Depth: 22.8 + 11.48
mg/1 and 40.78 + mg/1 in 1980 and 81 respectively).
Table 7-1 shows the mean, standard deviation, standard mean error and
coefficient of variation for the 1980-1981 slack tide surveys. Table 7-2
shows the same survey data by years and depth range for the slack tide
station surveys.
46
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SECTION 8
TEMPORAL VARIATION OF WATER QUALITY VARIABLES
The following is a discussion of the temporal variability of water
quality variables observed in the Patuxent Estuary from 1980-1981. Figures
8-1 through 8-20 are plots containing both the intensive and slack, water
survey station concentrations, with surface, bottom, and average values as
well as the maximum and minimum values observed during the 24 hour
intensive surveys shown. From these plots one can determine potential
seasonal trends. It can also be determined how data collected during a
twenty-four hour survey, i.e. minimum and maximum values, compare with the
limited number of observations (2 samples) collected during the slack tide
surveys at a given station. These graphs show that variability of chemical
constituents can be substantial during a 24 hour period, and that slack,
water data collected on one day should be interpreted as representing the
station monthly trend at a particular station location only within an order
of magnitude.
Salinity plots are shown in Figure 8-1 and show low summer and early
fall values due to low rainfall during this period. The up river stations
do not show as great a difference between the 1980 and 1981 data. It can
be seen that stratification or the minimum and maximum value observed
during the April 1981 intensive survey is much greater than the rest of the
year. This greater range between maximum and minimum values could have
been a result of stratification due to freshwater inflow from a storm event
that occurred before the survey.
The temporal plots of temperatures are shown in Figure 8-2. The plots
indicate that during the summer temperatures were slightly higher In 1980.
As expected, the temperature range observed during the intensive surveys
were greater. Surface to bottom temperature differences seldom exceeded 1
to 1.5°C during the slack survey.
The pH plots in Figure 8-3 do not indicate any significant seasonal
trend. In fact the range is so large at many stations during the intensive
surveys, one might question the ability to approximate seasonal pH at a
given station using the slack tide data. For example, the range observed
during July 1980 intensive survey at station XED4892 (mile 25.5) is larger
than the seasonal trend for the year. This is not the case however at
station XED9490 (mile 30.6), where the range of pH values are comparatively
quite small for the entire study period. It can also be observed that the
pH range is smaller in the upper river when compared to the lower river.
47
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Temporal plots of secchi disc (Figure 8-4) In the lower river stations
show a marked reduction of secchi depth during the summer months. This is
due to an increase in algal growth. The mid estuary stations, especially
station PXT0402 at nautical mile 35.2, shows consistently low values. From
nautical mile 25 to 40, (where the turbidity maximum region lies) the
Patuxent River experiences minimum light penetration throughout the year.
The upper estuary follows the same pattern as the lower estuary with good
visibility in the spring and winter and low values in the summer.
Figure 8-5 shows the temporal variability of dissolved oxygen. As
expected, low summer concentrations are observed. The lowest values
observed during the study period are in the lower river at stations XDE5339
(mile 13.9) and XDE9401 (mile 19.9) where estimated flushing times are
greatest. It can be seen that the range of values observed during summer
months is much greater due to increased biological interactions and
temperature effects on oxygen solubility. The July average dissolved
oxygen in the lower estuary was 5.0 + 2.0 mg/1. During August the middle
estuary showed lower average values in the 3.1 to 10 ppt salinity range
(5.1 + 1.1 mg/l) during the study period. The average D.O. at XDE9401
during 7/24/80 was 4.89 + 2.46 with a minimum value of 1.5. The
coefficient of variation was 113 with a standard mean error of 0.58 during
this intensive survey. Four days later a slack survey indicated a mean
D.O. of 6.4 + 0.35, and coefficient of variation (CV) of 5.5 at the same
station. It can be seen from analysis of this station that slack surveys
provide quite different results concerning the D.O. conditions in the
estuary. If one is interested in determining statistically valid D.O.
conditions in the lower estuary, detailed sampling is needed.
Mid-depth dissolved oxygen in the upper river indicates minimum values
occur around 4.4 mg/1. The twenty four hour variability at these stations
are much less than expected, however D.O. variability increases around
nautical mile 42.9 (station PXT0494) above Western Branch. Jug Bay (PXT
0455) station data is not as low as expected. The CV at PXT0455 during the
study period was however higher than the other two up river stations for
DO. Average DO was lower at the Rt. 50 station (5.7 + 1.36; min 4.1; max -
10.39) when the upper stations are compared.
Dissolved oxygen saturation (DOS) was highest in March (100.9 + 5.9%)
and April (94.8 + 11%) and plots are shown in figure 8-6. July DOS was
66.9 + 26.9% in the salinity zone greater than 10 ppt salinity. At the
upper river stations, mid-depth samples show Jug Bay waters have a higher
saturation (78 + 12%) and at Rt. 50 (PXT0603) saturation is lower (61 +
8%). Maximum D.O. saturation in the upper river occurred at Jug Bay
(104%). The Rt. 50 station maximum was 81%. The greatest saturation was
observed at the station on Western Branch (min-58%, max-146%). The station
with the greatest DOS variance was XDE2599. The data collected during the
intensive river surveys again show the large diurnal variance when sampling
occurs over a 24 hour period. For example, the variance of DOS observed at
station XDE2599 during the July, 1980 survey was 635%. A slack survey
conducted four days later gives the variance as 28%. This same magnitude
48
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on difference between slack water and intensive river surveys exists at
station PXT0603 where the July, 1980 intensive shows a DOS variance of 654%
and the slack water survey 4 days later gives a variance of 56%.
Dissolved nitrite values are surprisingly high in the lower river from
August through October (see plots in figure 8-7). An obvious nitrite
maximum is observed near Benedict from mile 0.1 to nautical mile 19.9.
This maximum appeared to peak in late August and is substantiated from both
1980 and 1981 data. In fact, further observation indicates that the peak
moves downriver from early August through early September. This movement
is somewhat faster than one might expect, due to our early first order
estimates of the flushing time in the lower estuary. A nitrite peak was
also observed in the mid estuarine zone in the spring of 1981. The two
uppermost mid-depth stations also indicate a nitrite peak in the fall of
1980. The peak concentrations observed in the lower and upper river occur
during the period of reduced freshwater inflow to the river. Average
nitrite concentrations during August 1980-1981 were 0.1 + 0.1 in salinity
zone 0-3 ppt; 0.02 + 0.02 in salinity zone 3.1-10 ppt; and 0.1 + 0.03 in
the zone greater than 10 ppt.
Data indicate that mid-estuary water samples on August 21, 1980 had
the highest concentration (4.3 x 10^ Colony Forming Units (CFU)/ml) of
Nitrosomonas species at station PXT0402 and sediment samples were highest
at mid-estuary stations PXT0455 (4.5 x 10^ CFU/gram wet sediment),
PXT0402 (3.6 x 10^ CFU/gram wet sediment), and XED9490 (7.6 x 10^
CFU/gram wet sediment). Nitrobacter species indicate the same similar
trend, i.e. where dissolved nitrate concentrations are low, bacteria levels
are high. It is hypothesized that high nitrite in the mid-estuary may be a
function of microbial-nitrification-denitrification processes.
Figure 8-8 shows that the temporal plots of dissolved nitrate are
generally high in the spring and fall months. This trend of decreased
levels during the summer is dominant in the mid estuary stations from
nautical mile 13.9 to 35.2. Lower estuary stations showed an increase in
the spring yet did not indicate a nitrate peak in the fall and early winter
in 1980. The last three upriver stations had relatively high concentra-
tions of nitrate throughout the year. The range of values observed during
the April 1981 intensive data is quite large. For example, on April 23,
1981 the nitrate C.V. observed during the intensive survey was 48.8 while 4
days later the slack survey data yield a C.V. of zero, thus indicating the
extreme variability between the two types of surveys. The lower river ( 10
ppt salinity region) reached an average maximum of 0.92 +2.2 mg/1.
Mid-estuary highest monthly values were observed in May 1981, with a mean
of 0.8 + 0.3 mg/l. Upper river average values peaked in May, with 1.28 +
3.5 m/1.
Figure 8-9 shows the temporal plots of ammonia. The stations near
Lower Marlboro (XED9490, 30.6) and up from there indicate fall and spring
maximum values. At Benedict (station XED4892) a maximum is observed in the
spring of 1981. In the lower estuary below Benedict the concentration of
49
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ammonia remains low with increased levels occurring in the summer. From
nautical mile 0 to 20, a summer ammonia maximum is observed. A summer peak
is also observed at mile 25.5 above Benedict. The variability of ammonia
during the summer in the lower river increases when compared to other
months. For example, at salinities greater than 10 ppt the mean and
standard deviation is 0.1 +0.1 mg/1 during June and July. Observation of
the coefficient of variation at the different stations document greater
variability in the lower river. This is believed to be a result of ammonia
flux from the sediments as indicated from increased summer sediment flux
measurements collected for this study. All stations in the estuary exhibit
this trend, although upper stations indicate potentially higher spring and
fall ammonia maximums.
Total organic nitrogen (TON) (figure 8-10 plots) shows generally
higher summer values. Results of the intensive surveys support the view of
extreme variability. Upper and lower river concentrations are not
substantially different as was the case for inorganic nitrogen.
Calculated total particulate nitrogen (TPN) concentrations are shown
in figure 8-11 plots. At Jug Bay (PXT0455, mile 40) a seasonal trend of
high early spring and fall concentrations is observed. Variability of TPN
is apparently greater in the lower estuary (mile 9). During slack surveys,
occasional surface to bottom concentrations range from approximately 0.2
mg/l to 0.8 mg/1. Surface values are generally higher in July and August,
however during spring, in the lower river (stations at mile 0 and 9) bottom
concentrations are higher. Near nautical mile 13 and 20, the bottom
concentrations are higher during the spring. The April 1981 high TPN
values at XED9490 may be due to high cell counts of cryptophytes and
crysophytes observed in this region of the river (see Section 11 figures).
Figure 8-12 temporal station plots indicate that total phosphorus is
relatively constant at the mouth of the estuary. Concentrations at the
mouth of the river are generally lower than upstream values. Plots of
salinity versus total phosphorus for the April, 1981 intensive survey
indicate simple conservative mixing may control the concentrations of total
phosphorus. At XDE2599 (nautical mile 9.6) the 24 hour survey on July 19,
1980 indicates a potential summer maximum of total phosphorus. The maximum
surface concentration indicates that a bloom of algae may have occurred in
the lower river, or the maximum value of 0.57 mg/1 was an outlier. At
nautical mile 14 to mile 25 the data indicate a definite total phosphorus
summer maximum. At mile 30 the variability of total phosphorus from surface
to bottom is quite high, especially when compared to the consistent range
of values observed at the lower estuary. Examination of Figure 4-6 shows
the hydraulic depth generally decreases in this area of the river and
Figure 4-14 indicates that mixing of freshwater and Chesapeake Bay waters
would, on the avierage, be maximum in this area. These two factors may
explain part of the reason why bottom concentrations in this turbidity max-
imum are so high, as well as nutrient flux being high in this region. Data
at station XED9490 (nautical mile 30) indicates an average concentration of
0.16 + 0.07 mg/1, standard mean error of 0.008 mg/1, C.V. of 41 and maximum
50
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and minimum values of 0.4 and 0.06 mg/1 respectively. At Nottingham
(station PXT0402, nautical mile 35.2) the average and standard deviation
for the study period was 0.2 +0.1 mg/1, standard mean error of 0.01 mg/1
and C.V. of 58, with a maximum and minimum value of 0.96 and 0.07 mg/1
respectively. Average values at the mouth of the estuary were 0.05 + 0.06
mg/1 (station XDE2599, mile 9) and 0.04 + 0.01 mg/1 (station XCF957T, mile
0.1). Data observed during this study indicate that the Chesapeake Bay may
not be a source of total phosphorus to the estuary, especially when one
notes the fact that surface to bottom concentrations at the main channel
station at river mile 9 are quite small and are not generally higher than
up estuary stations.
Dissolved phosphorus temporal plots tend to indicate that bottom
waters are not a source of dissolved phosphorus (see Figure 8-13 plots at
stations XCF9575 and XDE2599). The data indicates that during 1981 surface
to bottom differences at station XDE5339 were greater than the down estuary
station, however in 1981 no significant surface to bottom concentrations
are observed. The sediment nutrient flux data collected by the University
of Maryland for this study (16) indicates that during the summer of 1980
and previous years data there is an August flux of phosphorus from the
sediments, which is probably why concentrations in bottom waters increase
in the summer and early fall of 1980 at station XDE5339. This summer
bottom water dissolved phosphorus peak is also observed at nautical mile 20
(XDE9401) thus substantiating fairly conclusively that the sediments are a
source of phosphorus in the lower estuary and not Chesapeake Bay waters.
The data at the next upriver station at mile 25.5 (XED4892) substantiates
this transport process of nutrient rich bottom waters as well as blooms of
dinoflagellates, cryptophytes and chrysophytes of phytoplankton occurring
at station XED4892 during late July of 1980.
Figure 8-14 shows the temporal plots of dissolved ortho-phosphorus.
During summer months, bottom waters are generally higher but this trend is
not consistent. The July 1980 survey indicates the surface values were
higher. Lower estuary stations indicate higher concentrations in the
summer and fall of 1980 compared to summer 1981 values. A maximum occurs
in mid to late fall in the lower estuary. In the mid-estuary a maximum
occurs earlier, except at mile 30 in the turbidity maximum area where
biological utilization of orthophosphorus is probably at its maximum, and
the peak is not therefore observed in the months of August and September.
Comparison of station XED4892 (mile 25.5) and station XED9490 (mile 35)
show opposite monthly trends. At mile 35.2 a minimum appears to occur in
the late summer and early fall. This data substantiates that the turbidity
maximum area is a very complex area of the estuarine system where trends
can reverse in only a few miles. The intensive survey maximum and minimum
surround what one may determine as a seasonal trend. Thus the slack
surveys, especially in the turbidity maximum portion of the estuary are
probably insufficient to characterize late spring, summer and fall
conditions of an estuary.
51
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Total particulate phosphorus plots (Figure 8-15) indicate no seasonal
trend in the upper river stations. From the mouth of the estuary to mile
25.5 there is a summer maximum. At mile 25.5 bottom concentrations were
usually higher. At station XED9490 values obtained during the 24 hour
surveys indicate extreme variability over a twenty four hour period. Thus,
discrimination of seasonal trends are probably not reliable if based upon
slack survey data.
Dissolved organic carbon plots shown in figure 8-16 indicate higher
fall concentrations at all stations. This variable was not collected
during the summer and early fall surveys. The variability of this
constituent is less than expected. DOC average concentrations were higher
in the 0-3 ppt range (17.0 +'4.9 mg/1) in October 1980 and lower estuary
values indicate an average of 13.2 + 2.6 mg/1. A DOC minimum occurred in
August with 3.9 + 1.1 mg/1 in the 0-3 ppt salinity region 2.2 +0.3 in the
3.1-10 ppt region and 1.7 + 0.8 mg/1 in the lower estuary. Total organic
carbon measurements taken during the summer of 1980 indicate higher
concentrations in the estuary in August and September. If 1980 T0C and
1981 DOC concentrations are representative of typical conditions, this
suggests that during the summer most of the carbon is in particulate form.
Figure 8-17 plots of pheophytin indicate no general monthly trends at
all stations. This variable, which is an indicator of dead algae, shows
extreme variability as evident from the range of observations taken during
the intensive surveys. Average concentrations during the study period
suggest that the most productive area of the river system is at Nottingham
(nautical mile 35.2) since pheophytin is greatest at this location (17.8 +
14.2 ug/1, C.V. of 80) followed by concentrations at Lower Marlboro
(XED9490) with values averaging around 13.78 + 10 ug/1, C.V. of 100. These
two stations (where concentrations are highest) are also In the turbidity
maximum region of the river. All lower estuary stations show a marked
reduction of pheophytin concentrations. For example, concentrations were
lowest in the lower estuary ( 10 ppt) during the months of June (2.6 + 3.7
ug/1), October (2.2 + 1.4 ug/1) and December (2.1 + 2.1 ug/1). Maximum
average concentrations of pheophytln-a were observed throughout the river
during May 1981 with the upper salinity (,0-3 ppt) zone showing average
values of 30 + 25 ug/1, the mid-estuary zone (3.1 - 10 ppt) of 18.5 + 19.3
ug/1 and the lower estuary ( 10 ppt) indicating average values of 6.5 + 2.7
ug/1. Greater values during this period might be expected since the April
1981 longitudinal phytoplankton results showed higher total phytoplankton
cell counts at all upper river and lower estuary stations. Algal cell
counts were also high In the July 1980 phytoplankton survey at stations
XED9490 (Lower Marlboro), PXT0402 (Nottingham) and at PXT0455 (Jug Bay).
Dissolved reactive silicate concentrations (see plots in figure 8-18)
indicate that a silica maximum occurs in the lower estuary during the
summer and early fall, with surface concentrations generally higher.
Station variability of silica is not as great as other nutrient variables.
The lower estuary stations' maximum values were observed during the summer
52
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and early fall. This seasonal trend still existed in the mid-estuary
accompanied by a spring peak. Up river stations indicated relatively
consistent values throughout the study period, with higher concentrations
observed during 1980 when freshwater input was lower. At station PXT0603
higher values in, 1980 (the dry period) indicate that groundwater may be a
major source of dissolved silica to the estuary.
Seston concentrations indicated by the total non-filterable residues
shown in figure 8-19 plots indicate a summer maximum at all upper river and
lower estuary stations. Mid-estuary stations (mile 25, 30, 35) indicate
much higher surface to bottom differences, with bottom concentrations being
higher during most surveys. The upper river area (0-3 ppt) observations
indicate higher concentrations in the spring and early summer, due to
higher freshwater inflow and high loads of detrital material. In the
mid-estuary (3.0 - 10 ppt) concentrations are highest throughout the system
with a maximum occurring in spring and again in August and September. The
spring maximum is probably a result of high spring storm runoff and early
phytoplankton blooms whereas during the summer values are probably high due
to primary production. In the lower estuary section is highest in March
and September with a minimum observed in May.
BOD^ temporal plots show, as expected, tremendous variability. For
example, during the 24 hour surveys at mile 20 (XDE9401) the maximum and
minimum values bound the apparent seasonal trend line. Trends do not
appear to be consistent from one station to the next. Statistical analysis
indicates that in the upper estuary (0-3 ppt) BOD^ is greatest during May
and September. In the salinity zone 3.1 - 10 ppt, BOD5 is greatest in
April and September. Due to the inherent variability of the BOD5
analysis, these trends are suspect, however intensive survey data during
July 1980 indicates a BOD5 of 2.8 + 1.3 mg/1 in the upper region (0-3
ppt); BOD5 of 3.7 + 2.1 mg/1 in the mid-estuarine region (3.1 - 10 ppt);
and 2.2 + 1.3 mg/1 in the lower estuarine region.
April 1981 values indicate an average BOD of 3.4+1.5 mg/1 in the
upper estuary, 2.3 +0.8 mg/1 in the mid-estuarine region and 4.0 + 1.6 in
the lower estuary. The C.V. for BOD5 is greatest at the Western Branch
ambient station and the lower estuary stations. The BOD5 average was
highest at the Route 50 Bridge, PXT0603 (4.2 + 1.6 mg/1) with a maximum of
8 mg/1. The minimum average BOD5 was observed at the Western Branch
station 1.8 + 1.2 mg/1, with a maximum of 7 mg/1, and minimum of 0.1 mg/1.
Table 8-1 shows the monthly average and standard deviation of
variables for the three estuary zones described above.
53
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SECTION 9
INTENSIVE WATER QUALITY SURVEY VARIABLE RESULTS
The following is a discussion of the results of the intensive water
quality surveys conducted July 24-25, 1980 and April 23-24, 1981. These
surveys were conducted in order to describe the short term variability of
the water quality variables. Longitudinal phytoplankton surveys, described
earlier, were also conducted at approximately the same time period (i.e.
July 24, 1980 and April 20-21, 1981) and are discussed later in the report.
Stage height and current velocity data were also obtained and plotted for
two stations (XDE2599 at 9.6 and PXT0402 at 35.2).
Figure 9-1 shows the results of the two intensive surveys for salini-
ty. Salinity stratification is quite small at the mouth of the estuary.
Higher surface values occurred frequently during July and less frequently
during the April survey. Average salinity at the mouth of the estuary for
the July survey was 14.5 + 0.5 ppt compared to 17.5 + 1.2 ppt in April. At
station XDE2599 stratification was slightly greater in July with a mean and
standard deviation of 13.5+0.7 ppt and 17.1 + 0.2 ppt in April. During
the July survey surface values were consistently higher than bottom waters
during the first part of the survey. Increased bottom salinities occurred
during the later survey period.
In April very little stratification was observed. At mile 13.9
(XDE5339) stratification appears slightly greater with the July and April
mean and standard deviation of 12.78 + 1.15 and 14.43 + 1.7 ppt respective-
ly. It is interesting to note that at these lower stations the range was
greatest over the 24 hour period at the mouth, with the maximum value of
18.5 and minimum value of 12.6. At XDE9401 (nautical mile 19.9) stratifi-
cation is still greater in July (a trend which is generally true for this
whole survey, with a mean of 11.3 + 1.18 (9 min - 13.4 max) ppt in July and
are 14+1.9 (11 min. - 17 max) ppt in April. While the influence of tidal
stage and velocity on salinity is only slightly noticeable at these lower
stations, at mile 25.5 (where the estuary becomes much shallower) the
effect of tidal forces is more evident, with a July mean and standard
deviation of 5.5 + 2.3 (0.7 min. - 9.0 max) ppt and for April the
statistics were 10.5 + 2.5 (7.6 min. - 14.9 max.) ppt. Thus, effects of
low flow conditions in July and high flow conditions in April become much
more evident at this station located in the lower region of the turbidity
maximum zone. See figures 9-20 and 9-21 for a comparison of tide stage and
current velocities in the river during the IWQS. Salinity is consistently
higher in the bottom water layer at this location, however stratification
54
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decreases during maximum current velocities. The effects of tidal action
on the 24 hour salinity variation increase, and reaches a maximum at mile
30.6 (XED9490) at Lower Marlboro. Mean and standard deviation of salinity
reached 11.3 + 1.18 ( 9 min - 13.4 max) and 14 + 1.9 (11.1 min - 17 max) in
July, 1980 and April, 1981 respectively. Thus, a range of 4-6 ppt occurs
at this upstream station over a tidal cycle. Higher salinity at the
surface is probably due to upwelling of bottom water due to bottom
topography. Salinity at station PXT0402 (mile 35.2) indicates a tidal
salinity range from 0.1 to 1.2 ppt, with slight stratification, dependent
on tide stage and currents.
Table 9-1 indicates that average river salinity was 65% higher during
July 1980, compared to the April 1981 data. The average river salinity
standard deviation for surface and bottom waters was relatively constant at
about 6.1 ppt. The surface to bottom salinity difference averaged around
3.6 ppt during the intensive surveys during both years.
Figure 9-2 shows plots of water temperature observed during the
intensive survey. At station XCF9575 the stratification is greatest during
slack tide conditions as expected. Average temperature differences between
surface and bottom waters in the estuary for these surveys was 1°C in
July 1980 and 0.1°C in April, indicating as expected, greater stratifica-
tion in the summer. Very little overall stratification was observed in the
spring. The most interesting plot is PXT0402 where the April 1981 data
indicates that bottom waters were consistently warmer than surface waters,
indicating a potential inversion of waters.
Plots of pH shown in Figure 9-3 indicate there is a slight relation
between pH and tide stage. During the July 1980 survey average pH in
surface water and bottom water was 7.18 and 7.13 respectively. In April
average values were 8 and 7.86 respectively at the surface and bottom.
Mid-depth upper river values were 7.02 and 7.14 in July and April. The
lowest pH occurred at XDE2599 (mile 9.6) during the April survey (6.4).
The maximum pH observed was during the same survey (9.4) at XDE5339 (mile
13.9). It was not uncommon for a pH above 8 to occur on several occasions
at several stations, and pH values tended to be more variable as indicated
by the standard deviation at the middle estuary stations. The pH appears
to be strongly affected by the current and stage height data, especially at
the mid and lower estuary locations.
Figure 9-4 indicates dissolved oxygen values observed during the
intensive river surveys. Station XDE2599 at mile 9.6 indicates a surface
water inversion half way through the July 1980 survey. This inversion is
verified from observation of salinity and temperature profiles. The same
process occurred at XED4892 (25.5 nautical mile) and at mile 30.6
(XED9490). At mile 35.2 it was not uncommon for surface and bottom values
to increase and decrease inversely during the 24 hour period, indicating
this region experiences potential upwelling of bottom waters. During the
April 1981 survey the surface to bottom ranges of observed D.O. is much
smaller than observed in July 1980 survey, as expected. The surface to
bottom inversion does appear to follow stage height and velocity changes
55
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to some degree. The upper three stations observed an average D.O. of 4.85
+ 0.71 mg/1 and 7.3 mg/1 during July and April, respectively. Bottom
samples in the middle and lower estuary indicated an average of 5.1 + 1.83
mg/1 in July and 8.57 + 1.23 in April. Surface values averaged 6.11 + 1.39
and 8.88 + 0.97 mg/1 in July and April respectively. Average 24 hour DO
was lowest at station XDE5339 (nautical mile 13.9) with a mean of 4.3 mg/1
and standard deviation of 2.7 mg/1 (min - 0.5 mg/1; max - 8 mg/1). During
the April survey average DO was lowest at station PXT0603 (nautical mile
54.2 - Rt. 50 Bridge) 6.3 + .7 mg/1 (min - 5.2, max 7.1 mg/1). D.O. was
greatest at WXT0045 (Western Branch) at 13.9 mg/1 in April, or 146%
saturation.
Dissolved oxygen saturation (DOSAT) plots are shown in figure 9-5. As
expected, DOSAT was greatest during the April survey with average surface,
mid-depth, and bottom values of 96 + 10%, 74 + 15%, and 92 + 13%
respectively. During the July 1980 survey surface, mid-depth and bottom
average river DOSAT were 80 18%, 58+8%, and 65 + 23%. Minimum DOSAT
observed during the 2 year period was observed at station XDE5339 during
the July, 1980 survey at 6.6% of saturation. The highest average DOSAT in
July was 100% at XCF9575 at the mouth of the estuary. Minimum 24 hour
average DOSAT occurred at PXT0603 (Rt. 50 bridge) and at PXT0494 (Rt. 4
bridge) with a mean and standard deviation of 63 + 6% and 70 + 6%
respectively, thus indicating a greater potential for biochemical activity
and utilization of oxygen in the upper tidal and non-tidal river in April.
During the July survey the minimum station 24 hour average and standard
deviation was 54 + 6% at the same upper river station (PXT0603) followed by
station XDE5339 below Benedict at 57 + 36%. The maximum station 24 hour
average was at station XED4892 (above Benedict) during July with 83 + 14%
followed by station PXT0402 (Nottingham) at 79 + 9%. The data suggests
that the primary productivity is high in the region above Benedict during
the summer. Below Benedict, algal respiration and/or decomposition may be
occurring, causing an oxygen demand in this region of the estuary.
Secchi disc plots (see figure 9-6) indicate very little response to
tide stage and velocity changes. It is interesting to note that these
measurements indicate that approximately no light penetration occurred for
several hours at some locations. Secchi depth was usually around 0.1
meters most of the time during the July survey and rarely exceeded 0.2
meters above nautical mile 25.
July IWQS nitrate plots shown in figure 9-7 indicate that from mile 19
to 35 there is a strong relationship between stage height and nitrate con-
centrations, especially at mile 35 (PXT0402) near Nottingham. Data at this
station indicates concentrations may range from 0.5 mg/1 to 1.5 mg/1 (a
factor of 3) due to tidal forcing functions. This relation is true at
several other mid-estuary stations as shown by the plots. This phenomena
results in a large standard deviation of observed values. At this station
in July, the mean was 0.97 mg/1 with a standard deviation of 0.33 mg/1 (min
is 0.5, max is 1.5 mg/1) for the 23 observations made during the 24 hour
period. During July the surface and bottom average values were 0.23 + 0.37
mg/1 0.22 + 0.34 mg/1 respectively.
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The April observations indicated higher concentrations of nitrate through-
out the river, i.e. surface: 0.36 + 0.47 mg/1 and bottom depth values:
0.32 + 0.44 mg/1. The average concentrations observed in the upper estuary
stations were 1.36 + 0.22 mg/1 and 2.13 + 0.3 mg/1 for July and April
respectively. During the July 24 hour survey dissolved nitrate was usually
highest at station PXT0603 (1.6,+ 0.19 mg/1). During the April survey, the
average dissolved nitrate concentration was 2.4 +0.16 mg/1 at this
station. —
Figure 9-8 shows the 24-hour temporal plots of nitrite. Concentration
fluctuations appear to be correlated with tidal stage with a small lag time
at the mid-estuary stations where tidal forces would be expected to
dominate mixing. April average concentrations indicate surface and bottom
concentrations were similar (surface -.0.02 + .03, bottom 0.03 + 0.3 mg/1)
as well as the July survey (surface 0.03 4^ 0.03, bottom 0.03 + 0.03 mg/1).
However, mid-depth stations in the upper estuary and tidal river indicate
almost a 50% increase in the July survey (0.23 +0.1 mg/1) as compared to
the April survey (0.14 + 0.04 mg/1). Higher July 1980 values are probably
a result of the below normal rainfall during the summer of 1980.
Average nitrite was highest during the July survey at station PXT0603:
0.36 + 0.08 mg/1 (min - 0.25, max 0.46 mg/1), at PXT0455: 0.16 + 0.02 (min
- 0.14, max - 0.2 mg/1) and station PXT0494: 0.18 + 0.004 (min - 0.17, max
- 0.19 mg/1), reflecting higher freshwater concentrations and resulting in
dilution at down river stations. Average April survey values were much
lower at station PXT0603, 0.15 + 0.01 mg/1, slightly higher at PXT0455,
0.18 + 0.04 tag/1 and lower at PXI0494, 0.1 + 0.02, indicating "Western
Branch as a potential source of nitrite-
Dissolved ammonia temporal plots during the 24 hour surveys are also
correlated with tidal forcing in the mid-estuary (station XED9490, PXT0402,
XED4892). These plots indicate that there is no consistent trend of higher
surface or bottom concentrations in this portion of the river over a 24
hour period. However, below this zone where mixing is greater, the bottom
ammonia concentrations are more than 50% higher in July, probably due to
sediment nutrient flux processes (see station XDE9401 mile 19.9). The
dissolved ammonia average for the entire river during these river surveys
indicate April values are higher at surface, mid, and bottom depths
(surface: July - 0.06 + 0.04, April - 0.2 + 0.24 mg/1; mid-depth: July -
0.29 + 0.14, April - 0.71 + 0.33 mg/1; bottom: July - 0.13 + 0.07, April
0.18 + 0.26 mg/1). April values show a much greater variability of ammonia
concentrations than the July survey when all station data is compared. The
reason for higher ammonia in April is not clear.
Comparison of ammonia concentrations in the lower estuary shows that
April concentrations are much lower. For example, at XDE5339 (mile, 13.9)
July average 24 hour survey data indicate an average and standard deviation
of 0.09 + 0.08 mg/1 compared to 0.02 + 0.01 mg/1 in April, concentrations
more than three times higher* Analysis of PXT0603 data (at Rt. 50 bridge)
indicates that freshwater concentrations of ammonia is an order of magni-
tude higher in April. The trend is not true at station WXT0045, therefore
57
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the high April ammonia concentrations may be resulting from wastewater
treatment loads. High water column ammonia in the lower estuary in July
could also be due to biological reminerallzation in the water column as
well as high sediment fluxes of ammonia.
Total dissolved organic nitrogen (TON) is shown in Figure 9-10 plots.
Correlation of TON with tide height is not as strong as with inorganic
forms of nitrogen as expected. However, at mile 30.6 there is a fairly
strong correlation. Water column concentrations are quite variable. It is
interesting to note that the apparent inversion of surface and bottom
waters at station XCF9575 (mile 0.1) did not apparently affect the
concentrations of observed DON.
Total particulate nitrogen (calculated) is shown in Figure 9-11 plots.
At the mid-estuary stations concentrations were generally higher early in
the survey at the surface and lower after sunset, indicating some type of
diurnal effect at surface and bottom depths.
Plots in Figure 9-12 indicate total phosphorus concentrations are also
associated with tidal measurements at particular locations. Bottom depth
values are generally higher. During the July 1980 survey, surface, mid and
bottom values averaged 0.02 + 0.37 mg/1, 1.36 + 0.22 mg/1, and 0.22 + 0.34
mg/1, respectively. April upper river and estuary concentrations were
slightly lower, (surface: 0.08 + 0.06, depth - 0.4 + 0.17, bottom - 0.11 +
0.1 mg/1). Visual observation of the change in values over the 24 hour
period indicate that tidal forces may be responsible for nearly a 100%
increase in concentration. Trends of lower estuary station concentrations
occurred in April, indicating higher values at XDE2599 and lower values at
the stations above and below this location. In the upper estuary and river
dilution of freshwater phosphorus concentrations are apparent, except
between stations PXT0455 and PXT0402 where concentrations do not change
between stations. This indicates a possible mid-river source of total
phosphorus.
Particulate phosphorus at station XDE2599 in April is correlated to
tidal stage, but this trend is not as evident during the July, 1980 inten-
sive survey (see plots in Figure 9-13). Calculated particulate phosphorus
is generally higher at bottom depths as expected. Tidal effects are
apparently strongest at mile 25.5 (XED4892), at the lower end of the
turbidity maximum region. Plots of dissolved phosphorus (Figure 9-14) did
not show a strong tidal association with changes in concentrations except
at mile 9.6 (XDE2599) in April, where concentrations increase by more than
a factor of three. On the average, dissolved phosphorus was higher during
the July survey (surface: 0.03 0.01, mid-depth: 0.21 + 0.13, bottom:
0.03 + 0.02). The mid-depth average (i.e. upper river stations) was the
same in July and April (0.21 + 0.13). It is obvious that statistical
analysis of the 24 hour survey data does not allow one to discriminate the
effects of tidal forces on the concentrations.
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Orthophosphorus concentration (figure 9-15) plots indicate that values
were affected by tide stage at mile 13.9 (XDE5339) and mile 25.5 (XED4892)
similar to other variables, especially in July, when salinity, temperature,
and D.O. stratification were generally greater. Bottom values were
generally higher, however this trend was seldomly consistent over the 24
hour period. Dissolved orthophosphorus was 3 times higher in July at
surface and bottom depths. Mid-depth concentration averages remained the
same during the July and April intensive survey. Surface and bottom
concentrations were the same magnitude, indicating averaging concentrations
over a 24 hour period masks the fine scale processes affecting concentra-
tions. In the lower estuary, an order of magnitude increase in orthophos-
phorus was observed at mile 9.6 (XDE2599) when compared to the upper and
lower stations, thus indicating a source of ortho-phosphorus at this
location. Mid-estuary concentrations follow trends of dilution in July.
However in April, mid-estuary concentrations increase above Benedict.
Figure 9-16 shows temporal 24-hour plots of dissolved reactive sili-
cate. Silica concentrations respond to river stage by changing concentra-
tions (an order of magnitude) at the mid-estuary stations, especially in
the area of the expected turbidity maximum zone. In fact, silica concen-
trations appear to be associated with tidal action more than any other
variable. Silica was higher in July, with mid-depth samples in the upper
estuary showing highest concentrations, as expected (see Table 9-1).
Pheophytin-a^ concentrations appear to be dominated by tidal action at
station XED9490 (nautical mile 30.6). Average river concentrations were
slightly higher in July as expected (see Table 9-1). Bottom values in the
mid-estuary are higher, indicating that the mid-estuary is a recipient of
dead algal biomass from blooms occurring above or near this region (see
figure 9-17 plots).
Total suspended solids (total nonfilterable residue) plots in figure
9-18 indicate strong tide stage related variation at mile 30.6. As with
other variables, concentrations can increase by a factor of three over a
tidal cycle.
BOD5 plots in Figure 9-18 indicate greatest variability over the
tidal cycle at mile 25.5 (XED4892). There is no apparent trend of higher
surface or bottom concentrations during both surveys. Table 9-1 supports
this observation with the July 1980 surface BOD^ average of 2.88 + 1.65
mg/1 and bottom BOD5 average of 2.27 + 1.33 mg/1. Mid-depth average
BOD^ was 2.51 + 0.53 mg/1 in July and 4.24 + 1.45 mg/1 in April.
Table 9-1 gives a statistical summary of data collected during the
intensive surveys.
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SECTION 10
HISTORICAL PERSPECTIVE OF DISSOLVED OXYGEN AND DEFICITS
Dissolved Oxygen in the Patuxent River
A major concern of water quality management for the Patuxent River is
the low concentration of dissolved oxygen in the deep waters of the lower
estuary. While summer dissolved oxygen depletion is a normal, naturally
occurring event in the lower Patuxent, historical records suggest that the
degree and duration of low dissolved oxygen concentration may be increasing
(59, 40, 16). Low dissolved oxygen concentrations result when oxygen
consumption in deep waters and sediments is greater than oxygen replenish-
ment from surface waters. Stratification of the water column effects
oxygen distribution by decreasing surface and deep water mixing, resulting
in decreased oxygen replenishment to deep water. It has been suggested
that low dissolved oxygen concentrations characteristic of deep waters in
the lower Patuxent may be due to inflow of oxygen poor water from the
Chesapeake Bay (65) or due to increased upstream domestic waste loading
(62). Low dissolved oxygen has been reported to cause oyster mortality at
depths greater than 5 meters, and environmental concentrations of dissolved
oxygen are reportedly approaching levels that can be expected to kill fish
(40).
Historical Dissolved Oxygen
A substantial amount of dissolved oxygen data for the Patuxent has
been collected since the 1930's to the present (e.g. 60, 61, 62, 63, 64).
Historical data was used in an effort to characterize trends in dissolved
oxygen concentrations and distributions over this time period.
Historical dissolved oxygen data was stored on the EPA ST0RET infor-
mation and retrieval system for analysis of historical D.O. and dissolved
oxygen deficits (DOD). Historical data sources included the Maryland
Department of Natural Resources Water Quality File, the Chesapeake Bay
Institute historical data and historical data compiled by the University of
Maryland for the EPA Chesapeake Bay program.
Table 10-1 shows the yearly mean dissolved oxygen, standard deviation
and number of observations made in the estuary, tidal river, and mainstem
river up to the USGS gauging station at Route 50. This table also shows
the correlation coefficient from linear regression of D.O. vs salinity for
the years 1936 to 1981. Figure 10-1 is a plot of the mean values. Yearly
60
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mean dissolved oxygen shows no clear trend through the years, as might be
expected due to different sampling locations and timing of sample
collection.
The river was divided into an upper zone (0.2-10.0 ppt) and lower zone
(greater than 10.01 ppt) based upon salinity. The division of the river
was selected based largely upon the classification of brackish water as
proposed by Ekman, 1953 (38). Table 10-2 shows the mean dissolved oxygen
in the upper river. Figure 10-2 is a plot of these mean values. It should
be noted that due to a limited number of values during some years, these
plots may be a misleading comparison. Values reported from 1936-1939 are
in the same range of values as in the late 1970's and 1980's, indicating
little change in conditions in the upper river.
When looking at the physical characteristics of the Patuxent, the
figures and simplistic calculations presented in section 4. point out
several items of interest. First, Figure 4-15 indicates where flushing is
maximum and where dissolved oxygen may be lowest. This is substantiated by
historical plots of dissolved oxygen versus salinity. Historical data and
data reported in this study indicate low dissolved oxygen is in the
salinity region of 11-14 ppt or approximately nautical miles 11 to 19.
Flushing times in this portion of the river are greatest as shown in Figure
4-15. Also, Figures in Section 10 show that the dissolved oxygen deficit
is lowest in the 3-4 ppt salinity zone of the river. This is around
nautical mile 33 to 34 and as shown in Figure 4-15. This portion of the
river is expected to have the smallest flushing time in the upper estuary.
In addition, Figure 4-14 shows that nautical mile 26-27 is the river
segment where there is, on the average, 50% freshwater and Chesapeake Bay
water. This is the location of an upestuary sill, which is probably the
result of the mixing and resulting geochemical processes which form and
precipitate sedimentary particles (26). This location is also the lower
extent of the turbidity maximum location in the estuary. Above this
location, the water quality of freshwater will probably dominate the
mainstem estuary. Above this reach (approximately mile 35-43) is also the
area where seasonal historical dissolved oxygen appears to show significant
seasonal downward trends.
Table 10-3 and Figure 10-3 show the yearly mean dissolved oxygen
observed in the lower estuary. Figure 10-1 also indicates no linear trend
of yearly mean average D.0.
One might expect that a yearly mean D.0. trend would be more evident
when historical data for the month of August was analyzed. Table 10-4 and
Figure 10-4 show the yearly mean dissolved oxygen for the month of August
from 1936 to 1981. Correlation of D.0. versus salinity substantiate lower
D.0. in the lower river as shown on Table 10-4.. Table 10-5 and Figure 10-5
show the August yearly mean D.0. in the upper river zone. No consistent
trend with salinity is evident in this zone. August yearly mean values are
generally lower than yearly means for the entire mainstem river and estuary
as expected. Figure 10-6 and Table 10-6 show the August yearly mean D.0.
in the lower estuary. Values during the late seventies and during this
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study do not appear to be different from data taken from 1936-1939, except
for the data taken during 1978. In summary, when D.O. is analyzed from a
yearly temporal scale, no distinct trends are evident for the estuary and
tidal river nor the upper or lower salinity zones. Such trends may be
deceiving, without knowledge of specific conditions occurring during and
previous to the time a measurement was made.
Plots of actual data taken during the years are shown in figure 10-7,
where D.O. is plotted against salinity for each year. It is quite evident
from examination of these plots that low dissolved oxygen was observed from
1936 to 1939. In fact, during this time period one can conclude that
frequent dissolved oxygen around 1-2 mg/1 in the lower river was not an
uncommon occurrence, especially in the area of the river where the relative
flushing time is greatest. Observation of these plots leads to the con-
clusion that low dissolved oxygen in the lower estuary at deeper depths has
not generally increased. Although some years show a greater tendency for
low dissolved oxygen, i.e. 1978 and 1963, one must take into consideration
that the number of observations taken during these years increased by a
factor of three to four, compared to the number of observations taken in
1937 and 1939.
In order to refine the gross yearly analysis above, the river was
divided into twenty segments along the reach of the estuary and upper river
as shown in Figure 10-8. Based upon these segments, dissolved oxygen was
analyzed on a seasonal basis. The results of a seasonal historical
analysis is shown in Figures 10-9 through 10-28. Plots of the dissolved
oxygen historical seasonal mean and standard deviation were calculated,
using data from the State of Maryland, Chesapeake Bay Institute, and
University of Maryland.
In all segments, except segments three and four, there is no apparent
trend through the years. This analysis provides the best evidence of
increasing low dissolved oxygen trends in the upper river at segments three
and four. This area is the tidal river, where the flushing time is greater
during low flow conditions, and before tidal processes have began to allow
mixing with Chesapeake Bay water. This area is above the upper extent of
the turbidity maximum area.
Historical Dissolved Oxygen Deficits
Measurements of dissolved oxygen are well known to be affected by
temperature and salinity. It is common practice to calculate the dissolved
oxygen deficit, sometimes called the apparent oxygen utilization. This
calculation was made as follows:
DOD = SD0-MD0 (10-1)
where: DOD = dissolved oxygen deficit (mg/1)
SD0 = calculated saturation value of dissolved oxygen
corrected for temperature and salinity (mg/1)
MDO = the measured dissolved oxygen, corrected for temperature
and salinity (mg/1)
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Historical data from the previously mentioned data sources were used
to calculate DOD whenever dissolved oxygen measurements were made in
conjunction with temperature and salinity or conductivity. If conductivity
and temperature were reported we calculated salinity based upon the formu-
lation given by Pritchard and reported by Westinghouse, 1972 (39). Satu-
ration of dissolved oxygen was calculated based upon an algorithm used in
the Maryland Water Quality File. This algorithm was verified using tables
given in Standard Methods, 1975 (11). The following is a discussion of
analysis of the calculated deficits by upper and lower river, 2.0-10 ppt
and greater than 10.01 ppt salinity.
Figure 10-29 shows the historical DOD according to depth ranges. Fig-
ure 10-19 also shows the mean and standard deviation of deficits or appar-
ent oxygen utilization in the upper estuary (2-10 ppt salinity) and in the
lower estuary (greater than 10 ppt). This division of upper and lower
salinity regions is approximately the same as Ekman's classification (38).
Figure 10-32 shows the mean and standard deviation of deficits in the
lower Patuxent estuary. Figure 10-30 shows the same values for the upper
estuary. Figure 10-31 shows values for the river in the region between
2-10 ppt salinity. It can be seen that the trend of yearly means from 1936
to 1981 in the lower river indicate a potential change towards saturation,
while regression of all values (over 5,000 observations) versus time
indicates a small trend towards larger deficits, that in turn indicate
lower dissolved oxygen (see figure 10-32). Figure 10-30 indicates a trend
towards greater deficits in the upper estuary when yearly means or all data
are regressed against time, however, the r^ indicates a very small linear
trend. Figure 10-31 indicates yearly mean DOD and DOD versus time does not
follow a trend.
Table 10-7 and 10-8 shows the actual mean and standard deviation of
DOD for the lower and upper river respectively. In addition, the trend of
DOD with respect to salinity is represented by the correlation coefficient.
Table 10-9 also shows the same information for the estuary within the
entire tidal river and estuary. From Heinle, et. al., 1980 (40) it may be
inferred that the standard deviation or range of the DOD would increase
over the years (due to greater phytoplankton productivity and respiration)
which may in turn increase the range of dissolved oxygen in a nutrient
enriched aquatic system. Evaluation of the historical DOD standard
deviation from 1945 to 1980 does not show this trend in the lower river,
and only limited evidence supports this view for the upper estuarine area
using data from many locations. Table 10-9 shows the standard deviation of
DOD for the entire river system and does not show any trend for increase in
the standard deviation of DOD from 1936-1981.
Tables 10-10, 10-11, and 10-12 show the average DOD for the years
1936-40, 1941-50, 1951-60, 1961-70, and 1971-81 for the upper, lower, and
entire river system respectively. Evaluation of the trends using this
temporal period does show larger deficits in the upper estuary. Only a
very small linear trend is indicated in the lower estuary and for the
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entire estuary when decades of DOD's are analyzed. No trend in the
standard deviation of DOD is observed. A gross evaluation of dissolved
oxygen deficits appears futile, especially when it has been shown that
tides and resulting mixing phenomena effect the stratification and
potential low dissolved oxygen in an estuary (16). However, when
substantial public funds are spent for waste water treatment, it becomes
necessary to fully substantiate statements concerning historical dissolved
oxygen trends, as well as to understand the limits of existing data for
determining dissolved oxygen trends.
In order to more fully understand historical dissolved oxygen deficit
trends, data was grouped into ten depth ranges as follows: 0, 1-5, 6-10,
11-20, 21-30, 31-40, 41-50, 51-60, 61-99, and 100-129 feet. Table 10-13
shows the yearly means, by depth, in the lower estuary. Table 10-14 shows
the mean DOD observed in the upper estuary at various depths. This Table
clearly shows where data collection is needed for future historical
analysis. Figure 10-19 shows the mean and standard deviations of yearly
mean DOD at various depth ranges. Regression of DOD versus years at
various depth ranges in the upper river indicate a slight trend towards
greater deficits (r^ = 0.2 at the surface and r^ = 0.202 at the 1-5 ft.
depth range). This data supports the view that surface water processes may
be utilizing greater oxygen in the upper river and may reflect nutrient
enrichment in the upper river. It should also be noted that observations
in the deeper waters have rarely been made, especially since the 1960's, as
indicated in Table 8-7. Figure 10-19 shows the dissolved oxygen deficits
at various depths in the lower estuary. Although only approximately 50
values are available for regression of DOD vs. time at the 61-99 ft. range,
an r^ of 0.43 is obtained when yearly mean DOD's are used. An r^ less
than 0.1 is obtained when all data are regressed versus time. Due to the
paucity of data taken at this depth this trend may be spurious. More data
is needed at deeper depths to substantiate this trend.
Greater oxygen utilization by biological and chemical processes is
expected to occur during the summer months, with smaller mean deficits
during the spring, fall and winter. Table 10-18 shows the monthly average
historical DOD by years in the lower river. This data shows greater
deficits during the summer months as expected. It is interesting to note
that large deficits have occurred in May (4-5 mg/1 range). Although the
largest monthly average deficits are observed in 1978, this is not due to
poorer water quality trends over the years, but to the station location,
depth and number of samples collected. This table shows that a substantial
amount of data exists historically for the month of August. Figure 10-33
shows the yearly monthly mean DOD for the entire estuarine area.
Table 10-19 shows the yearly mean deficits currently available for the
month of August at various depths in the upper estuarine zone. No linear
trend is observed at any depth range. Values at the surface show no linear
trend over the years (r^ = 0.0). As expected, deficits do increase with
increasing depth. Table 10-21 shows DOD in the lower estuary for the month
of August from 1936 to 1981. Even in the lower estuarine zone a substan-
tial amount of data is currently lacking for making a sound historical
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trend analysis in deep water. Only nine years of data is available for
trend analysis at depths of 21-30 ft. No linear trend (r^ = .02) exists
through the years at this depth range. The same is true for surface values
(0-5 feet), where eleven years of mean August DOD shows no linear trend
(r^ = 0.00). Based upon this information it would appear that all yearly
mean August DOD's do not enable one to reject the hypothesis that the lower
estuary has not been degraded as indicated by increasing oxygen utili-
zation. Attempts should be made to obtain other existing data that would
enable rejection of this hypothesis for August DOD's.
Due to the fact that more data exists during August than other months,
an analysis of DOD by time of day was carried out. Table 10-22 shows the
DOD in August during daily time intervals at various depths. Lack of data
taken at various depth and time ranges precludes more detailed analysis,
however, there is a trend for mean average DOD to increase during the day
from 9-10 a.m. and decrease from mid-day, evening and night.
In the upper river the mean DOD is greater from 3-8 a.m. probably due
to phytoplankton respiration (see Table 10-22). In the upper river the
data suggest DOD then becomes lower from 9-10 a.m. and again increases from
II a.m. to 6 p.m., with the minimum DOD estimated to occur from 7 p.m. to 1
a.m. In the lower river (see Table 10-24) the deficits are again lowest
from 7 p.m. to 1 p.m., increase during the period 3-8 a.m. and reach a
maximum depth average of approximately 2.38 + 1.89 mg/1 from 9-10 a.m.,
with lower average values occurring from 11 a.m. to 6 p.m. An apparent
trend exists during August for larger deficits to have occurred from
1936-1940 to 1971-1981 in the upper river from 1-15 feet, from 9-10 a.m.
and 11 a.m. to 6 p.m., however the number of samples collected in the
1930-40 time period may not be representative. No apparent trend occurs in
the lower river during August, at any depth range or time period.
Historical July and August DOD averaged by depth range and years for
the total estuarine system also indicate that DOD is greatest from 9 a.m.
to 10 a.m. decreasing mid-day, reaching a minimum at night and increasing
again from 3-8 a.m. (see Table 10-25). In the upper river (Table 10-26)
historical July and August averaged DOD by time and depth increase around
3-8 a.m., decrease from 9-10 a.m. and reach a maximum from 11 a.m. to 6
p.m. Similar to historical August data, when historical July and August
data are averaged in the lower river, the maximum is reached from 9 a.m. to
10 a.m. (see Table 10-27).
After combining historical July and August DOD, no apparent linear
trend of increasing DOD through the years is noticeable. It is interesting
to note that lower river DOD tends to reach a maximum from 9 a.m. to 10
a.m. and the upper river data supports the view that maximum DOD is
observed midday, 11 a.m. to 6 p.m., and again from 3 a.m. to 8 a.m.
Detailed review of all monthly DOD showed that there are not enough
values during months other than July and August at various depths to
evaluate potential historical trends.
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Selected plots of yearly DOD versus salinity are shown In figure
10-34. These plots clearly show DOD is close to 8 mg/1 in the late 1930's
in the lower river. Positive values are indicative of low dissolved oxygen
and negative deficits reflect supersaturated values.
Figure 10-35 and figure 10-36 also indicate that DOD is close to being
a normally distributed variable. Figure 10-35 indicates that data taken
from 1939 to 1940 tended to be slightly lower than 1980-81 data. This
analysis would tend to support a general shift towards greater deficits at
all DOD ranges since the late 1930's. The 1980-81 data indicate little
change from the historical average except larger deficits at the extreme
probability ranges, i.e. near zero and 100%. Comparison of 1980-81 to the
late 1930's data indicates that the percentage of time that large deficits
occurred was the same, however there is a small shift from lower to higher
values in the small to negative deficit range. Thus the percent of time
that low dissolved oxygen would be expected to exceed has probably not
changed from the late 30's to 80's. However, the percent of the time that
deficits between approximately 2 to -2 mg/1 would be expected to occur has
changed, thus indicating a general upward shift of DOD's. On the other
hand, it could be argued that the 1930's data was not representative of
conditions in the late 1980's.
Figure 10-36 indicates the distribution of DOD is similar in the upper
estuary and lower estuary with the exception that the upper river can be
expected to experience greater dissolved oxygen saturation than the lower
river, and that the lower river can be expected to have larger deficits,
more often than the upper river, as expected.
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SECTION 11
RESULTS AND DISCUSSION
The Patuxent River is one of the most extensively studied estuarine
systems on the east coast, with water column nutrient studies initiating in
the 1930's (66, 60) and continuing through to the 1980's (62, 30). The
following is a discussion of the results of special analyses performed on
data collected during this study in order to identify and characterize
relationships between various estuarine water quality variables and
processes.
Longitudinal Characterization
In order to classify longitudinal zones of similar water quality
characteristics, the Duncan multiple range test was applied to the slack
water and intensive mainstem station data. The results of this statistical
test are shown in figures 11-1 through 11-8, and indicate areas (i.e.
stations) in the river, which have similar concentrations or characteris-
tics. Stations that are not significantly different are shaded similarly.
These figures also show the mean value at each station for the respective
water quality variable and nautical miles. The depth profile of the
Patuxent has also been shown on these figures to emphasize the general
water depth of the river.
Figure 11-1 indicates the upper river near Rt. 50 (PXT0603) is a
unique area of the river for BOD5, with generally higher concentrations
as indicated by the mean value of 4.2 mg/1. The Duncan's multiple range
test indicates the rest of the river may be considered a separate zone or
region. Alkalinity measurements during the study indicate the upper river,
approximately nautical mile 55-50 and around mile 35 are similar. There is
some similarity in the lower river from mile 0 to 10 and from around mile
15 to mile 5. Three distinct areas, upper river, mid-estuary (turbidity
maximum area) and the lower estuary appear to exist for pH.
A pheophytin-«i zone in the lower estuary is apparent (figure 11-2) and
this same classification exists in the upper river, however from the
turbidity maximum region (upriver) the river can be considered quite
variable, with distinct zones indicated at each station. A total nitrogen
zone is apparent in the lower estuary, while upriver stations are all
fairly unique except from nautical mile 40 to 50, in the major portion of
the tidal river. Salinity characterization using the multiple range test
indicates that the lower estuary (mile 0 to 10) is similar, however above
this area each station and associated zone of the river is unique. It is
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Interesting to note the change of mean salinity between mile 30 and mile 25
mean concentration, i.e. 2.7 and 8.4 respectively. This is the area of the
river where the rate of mixing of fresh and saltwater is greatest. Figure
11-3 indicates three chlorophyll-^ zones in the river. The results show
the* turbidity maximum region as a distinct area. This chlorophyll-a
measurement was uncorrected for presence of pheophytin. The "corrected"
(for presence of pheophytin) chlorophyll-^ figure indicates there are
several unique zones, one at the mouth of the estuary, a long lower and
upper estuary reach and a tidal fresh reach. A sub class or group is
present in the turbidity maximum region and the upper reaches of the tidal
river. Silica values indicate a freshwater-tidal river reach and two lower
estuary reaches which overlap. The mid-estuary, in the turbidity maximum
appears to be a combination of classes.
Figure 11-4 indicates the turbidity maximum region is also a fairly
unique reach of the river for temperature, with overlapping station simi-
larity in the lower and upper river reaches. Several dissolved oxygen
reaches are indicated, one at the mouth of the river, one lower estuary
zone, three zones in the turbidity maximum, and an upper river zone. Since
this analysis is based upon a composite of all station depth values, the
lower dissolved oxygen in deeper waters is not apparent. Total non-filter-
able residue clearly indicates the expected zone of the turbidity maximum,
with the upper and lower river reaches showing similarity. Figure 11-5
indicates that nitrite is quite variable, however, a middle and lower
estuary zone is also apparent. Ammonia is also quite variable from station
to station, however two lower estuarine reaches are indicated. Similar to
salinity, a lower estuary zone and an upper tidal river reach is indicated.
A distinct orthophosphorus (see figure 11-6) reach is indicated in the
lower estuary. In the turbidity maximum region two zones are apparent and
the tidal river appears as a unique class. Dissolved phosphorus is quite
similar throughout the main estuary, however stations in the upper river
and tidal river indicate distinct reaches. Total organic carbon observa-
tions clearly indicate a distinct reach in the turbidity maximum region, a
lower estuary reach and a tidal river, reach, which extends into the
estuary. The dissolved nitrogen classification plot (figure 11-7) indi-
cates unique zones in the upper river and estuary and one zone in the lower
river. This same trend exists with nitrate. Total phosphorus analysis
using this classification technique indicates several upper river and
mid-estuary zones and one lower estuary reach. Dissolved oxygen saturation
shown in figure 11-8 indicates a unique upper estuary reach, and a lower
estuary reach. The upper turbidity maximum region (mile 35) is unique with
the highest mean dissolved oxygen saturation. Dissolved organic carbon,
also shown in figure 11-8 indicates several zones which are similar but
discontinuous by unique areas above and below the turbidity maximum region.
Additional Duncan multiple range tests were applied to all the data
collected at the surface and then to data collected at bottom depths.
Figures 11-73 through 11-80 present the longitudinal characterization of
nutrient parameters for surface values. The bottom values are revealed in
figures 11-81 through 11-88. A combination of surface and bottoms station
data was shown in figures 11-89 through 11-95.
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BOD5 had three zones at the surface and only two at the bottom. At
the surface the river from 0-5, 17-22, and 28-33 nautical mile were
characterized the same with the lowest average values. The surface water
from 5-17 nautical mile had the same biological characteristics as the last
station at 35.2 (PXT0402). The bottom layer was similar in BOD5 values
except the last station 35.2 (PXT0402).
Total alkalinity had six distinct groups at the surface (figure 11-73)
and four separate groups at the bottom (figure 11-81). The greater
division at the surface could be caused by a three layer flow condition
that affected surface concentrations. Comparing surface and bottom
stations together (figure 11-89) there are four zones. The surface and
bottom have similar characteristics from the mouth to nautical mile 20.
The region from 20-35 was homogeneous and had the lowest alkalinity values.
The bottom and surface values for pH have two and four regions
respectively. The bottom had one zone in the lower estuary and another for
the mid and upper estuary. The surface also had a distinct zone in the
lower estuary but the mid and upper estuaries were different.
For pheophytin-«i the surface data was broken into four separate
regions. The largest area was from 0-20 nautical mile and this region had
very low average values. The upper estuary had three small zones that
increased in pheophytin-a^ measurements as it went up the estuary. Bottom
values had four groups equal in size: the lower estuary region, two
mid-estuary regions, and an upper region. The pheophytin values are fairly
stable in the water column of the lower and mid-estuary but vary a great
deal in the upper estuary both longitudinally and horizontally as seen in
figure 11-90.
Total nitrogen concentrations were similar for both surface and bottom
values from 0-20 nautical mile. The mid-estuary from 20-30 miles was
similar for the surface but divided into two zones for the bottom layer.
The upper estuary, at station PXT0402, was distinct for nitrogen with no
stratification in depth.
Salinity values are broken into many zones longitudinally. This
stresses the conservative nature of salinity with fresh water flow.
Surprisingly though, salinity does not present much stratification in
depth. The only distinct division within the water column was from
nautical mile 10-20.
Chlorophyll-a had four regions at the surface and two at the bottom.
Surface values were greater than bottom values, indicating the dependence
on sunlight. For the surface and the bottom values there was a large
distinct area from 0-20 nautical miles. The upper estuary for the surface
was segregated into three separate regions but the bottom values had only
one region. When chlorophyll-a was corrected for phepphytin the surface
region was no longer divided and only one zone was present.
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Silica had definite regions for both the surface and bottom data.
Silica appeared to be a conservative substance that Increased in
concentration as it went up the river. For both depths station XDE4892
(25.5) and PXT0402 (35.2) were similar as seen from figures 11-75 and
11-83.
Average Patuxent temperatures are homogeneous longitudinally with only
one zone present for the surface and bottom.
Data portrays dissolved oxygen (DO) as homogeneous at the surface yet
very divided at the bottom. This suggests a healthy DO was present at the
surface yet becomes depleted at the bottom. When both depths were looked
at (figure 11-91), there were only three zones for DO. The river near
station XDE5339 (13.9) was depleted with an average DO of 5.9 mg/1.
Total residue has three disjoined regions at the surface, from 0-15,
15-20 and 20-35 nautical ¦milps. The bottom had only two zones. Values
increased longitudinally as they went up the river.
Dissolved nitrite characteristics had three disjoined zones for both
the surface and the bottom values as seen in figures 11-77 and 11-85.
Higher values were seen in the upper estuary.
Dissolved ammonia had three dissimilar zones at the surface and two
zones at the bottom. When surface and bottom data were compared together
six zones were indicated. This suggests that ammonia was very stratified.
Dissolved nitrate plots in figures 11-79, 11-87 and 11-92 were for
surface, bottom and combined data respectively. The surface and bottom
were divided into five and three zones. At the surface the station at the
mouth was an isolated zone with other regions located at 5-25, 10-15, 30
and 35 nautical miles. The bottom depth had one large region from 0-25
nautical miles with two smaller regions in the upper estuary. The combined
data indicates five regions with little stratification.
Chloride values for surface, bottom and combined data were broken into
six, five and five zones respectively. Chloride was conservative with
little or no stratification.
Dissolved phosphorus figures have four zones at the surface and four
at the bottom and were shown in figures 11-78 and 11-86. The area from
nautical mile 0-15 was similar at the surface and bottom depths. This was
even the case when surface and bottom values were compared together (figure
11-94). At the surface three separate zones were located at XDE9401 (20),
XDE4892 (25) and at the last two estuary stations from 30-35 nautical
miles. When the depths were combined for dissolved phosphorus there was
little stratification seen except at station XDE9401 (19.9) and XED9490
(30.6) (figure 11-94).
Dissolved ortho-phosphorus was divided into four groups at the surface
and five at the bottom. At the surface the lower estuary was similar from
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0-15 nautical miles but the bottom had two zones in this area. The region
at nautical mile 20 was distinct for the surface and bottom data with
simularity to this region from nautical mile 30-35.
The total organic carbon (TOC) characterization had three regions for
the surface and only one homogeneous region for the bottom layer. The
surface had a lower estuary area between 0-10 nautical mile. The next
region was shown in figure 11-73 from nautical miles 10-20 and 30-35. At
station XDE4892 (25.5) the highest TOC average concentration portrayed by a
separate zone at the turbidity max and indicating greater ecological
activity.
Dissolved organic carbon in figures 11-80 and 11-88 for surface and
bottom data respectively were divided into three different zones. At the
surface the station located at the mouth of the Patuxent was an independent
zone with two larger zones following it. At the bottom the first zone was
located from 0-15 and 25-30 nautical miles. Then two smaller zones were
observed at 20 and 35 nautical miles with average concentrations of 3.8
mg/1 and 6.9 mg/1 respectively.
Total particulate phosphorus was presented in figures 11-80, 11-88 and
11-95. The surface had a large region from 0-20 nautical mile with very
low concentrations. Three smaller zones were in the upper estuary with
higher, more variable concentrations. At the bottom the first zone was
from 0-15 nautical mile followed by smaller zone at mile 20 and between
25-35. Combined data had five separate regions with no stratification
present in the first 10 nautical miles.
Application of the multiple range test does not provide insight into
processes that may be responsible for differences between stations or
station similarity, which has been extrapolated to make inferences concern-
ing river reaches or zones. It is apparent, however, for several varia-
bles, zones of similarity exist between the lower, mid-estuary and tidal
river portions of the river as expected. Further application of such
simple cluster techniques to other estuaries might prove useful for
comparative estuary characterizations.
Nitrogen to Phosphorus Ratios
The longitudinal profiles of the total N:P ratios (calculated on a per
weight basis) and the Redfleld N:P ratio are presented In plots of slack
water survey data (see figures 7-20 and 7-21). Previous studies concerning
coastal eutrophication have indicated that unicellular marine algae
assimilate nitrogen and phosphorus in a ratio of 10:1. Assuming these are
the growth rate limiting chemicals for algal growth in the Patuxent, it can
be assumed that if the N:P ratio is greater than 10:1 there is an abundance
of nitrogen, and phosphorus may be the limiting growth nutrient. If the
ratio is less than 10:1 then nitrogen may be the algal growth limiting
nutrient. Total N:P plots indicate phosphorus is limiting at the mouth of
the estuary most of the time, decreasing to nitrogen limitation below the
turbidity maximum region and increasing towards phosphorus limitation in
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the turbidity maximum region of the estuary. Above the turbidity maximum
region, total N:P ratios would indicate nitrogen limitation. Plots of the
dissolved N:P ratio, i.e. Redfield ratio (NO^+NO^+NHj/orthophos-
phates) indicates potential phosphorus limitation at the mouth, with
occassional nitrogen limitation. A general trend towards nitrogen limita-
tion is indicated below the turbidity maximum region and the greatest
phosphorus limitation in the turbidity maximum region. A trend towards
nitrogen limitation is indicated in the upper river, although the upper
river values are close enough to the 16:1 ratio that the system probably
shifts quite often, probably dependent upon freshwater inflow related to
storm flows.
A more detailed evaluation of the total N:P profiles indicates an
association between the shape of the longitudinal N:P profile to the
antecedant rainfall/runoff conditions. Analysis of daily mean flow
hydrographs at the Route 50 USGS gauging station (PXT0603) indicate that
the greater the time period before the last storm event (peak in hydro-
graph) and the slack water survey, the more the profile fits an exponential
function (see the September 15, 1980 slack survey plot). A formalized
analysis was performed which indicates how close the slack survey data of
total N:P fits an exponential function. How well the slack water profiles
of the total N:P fit an exponential curve can be represented by correlation
of the N:P ratio versus nautical mile.
Plots of the resulting regression coefficients against antecedent
conditions, i.e. number of days between the slack water survey and the (a)
beginning of a storm, (b) the end of the storm, and (c) the middle of the
storm, are shown in figures 11-9 and 11-10. Thus, there is an apparent
relation between the total N:P longitudinal profile in the Patuxent River
and storm events which deliver higher nitrogen and phosphorus loads to the
river system. It is hypothesized that the mid-river phosphorus limited
waters may be strongly related not to biological processes but to input of
nitrogen rich waters to the estuary as a result of the stormwater inflow.
As indicated above the September 15, 1980 slack water survey had no
pronounced mid-river peak (indicating phosphorus limited water), however
the survey was conducted more than 30 days after the last storm event as
evidenced from the Rt. 50 hydrograph. In an attempt to explain more
explicitly the factors affecting the longitudinal variation of the dis-
solved N:P ratio, curvilinear stepwise statistical regression was applied
to the data. The N:P ratio was used as the dependent variable. The
independent variables which explained 75% of the variation of the N:P ratio
were: nautical mile; salinity; days from beginning, middle, and end of the
storm to the survey date; storm characteristics describing the size of the
storm. This regression analysis substantiates several viewpoints. First,
the apparent nitrogen or phosphorus limitation anywhere in the river
(nautical mile 0 to 48) is highly dependent upon the physical characteris-
tics reflected in salinity and location along the river. Second, the
timing of water quality sampling with respect to the last rainfall/runoff
event affect the data collected from slack water surveys and thus conclu-
sions concerning whether the estuarine system or a portion of the system
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tends to be nitrogen or phosphorus limited. Thus, statements regarding
whether the Patuxent River is nitrogen or phosphorus limited should take
into consideration the previous 30 day freshwater inflow regime, and the
salinity distribution. The regression equation obtained for the Redfield
Ratio is:
R = -0.499 (InM) + 0.425 (lnQs) + 0.429 (InA,,,) 11-1
-0.19 (ltiAe) -0.372 (lnQm) -0.151 (InS)
+0.836 (lnQa) -0.126 ( Qa) -0.269
where:
R = dissolved N:P ratio i.e. NO2+NO3+NH3/
Orthophosphorus (mg/1 -N,P)
M = nautical mile
Qs = sum of mean daily CFS from beginning to end of storm (CFS)
Ajjj = number of days from survey date to the middle of the
previous storm (days)
Ae = number of days from survey date to the end of the previous
storm (days)
Qm = peak mean daily CFS of antecedant storm event (CFS)
S = salinity (ppt)
Qa = average mean daily CFS from survey date to beginning day
of antecedant storm
Deletion of five oTit of 202 observations of the N:P ratio that were
indicative of outliers (using Cooks distance) reduced serial correlation to
below 0.01 and resulted in a multiple correlation coefficient (r^) of
0.75. This regression was performed using the BfQP, P9R, multiple linear
regression program (41). Application of the same general procedure,
although not as extensively to the total N:P ratio yielded squared multiple
correlation coefficients greater than 0.5.
I
Water Quality Variable Cumulative Frequency Distributions
i
Cumulative frequency distributions are useful for describing not only
the nature of a water quality variable distribution but to compare and
evaluate variables against which a water quality standard exists. In the
Patuxent River, the first published CFD was presented by the FWPCA, 1968
(19) at the Rt. 50 bridge crossing the Patuxent River. Data reported at
that time indicated that 50% of the time, dissolved oxygen would be
expected to be 4.6 mg/l in June, 4.5 mg/1 in July, 5.0 mg/1 in August, 5.9
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mg/1 in October and 7.4 mg/1 in May, based upon data collected in 1967.
Cumulative frequency distributions are useful because they provide informa-
tion concerning the extreme values, median concentrations and provide
insight into what percent of the time one would expect to observe a value
or a concentration range to be exceeded, equal to or less than another
value or a standard. Water quality variables are known not to be normally
distributed, although published literature concerning this fact is quite
limited. Thus, care must be taken in applying parametric statistical tests
that in many cases are dependent upon the sample population being normally
distributed. Figures 11-11 through 11-21 show the cumulative frequency
distributions of water quality variables collected during this study. Two
plots have been developed for each water quality variable in order to show
the slack water survey data and the intensive water quality survey data.
Although these have been developed for the entire data base collected
during this 1980-81 period, they can be developed for unique salinity
regimes and stations in order to compare trends. Figure 11-11 indicates
that the expected dissolved oxygen distribution for the entire river from
the intensive two surveys is almost the same as the data for the slack
surveys. This raises the question of the need for slack surveys necessary
to characterize dissolved oxygen in a river system. In fact, for many of
the variables the two intensive surveys provide similar distributions.
These graphs also indicate the degree to which variables are normally
distributed. The only variable which appeared to be normally distributed
was dissolved oxygen.
Secchi disc is less than 0.1 meters more than fifty percent of the
time in the Patuxent River based upon the 1980-81 data. Approximately 98%
of the time secchi disc is expected to be less than 0.4 meters. A CFD was
developed for the N:P ratio and indicated 50% of the time the river and
estuarine system would be expected to have an average Redfield ratio of 7
indicating nitrogen limitation. Similar types of figures and statements
may be useful for comparing different water quality conditions in different
regions of the Chesapeake Bay, as well as different regions within the
Patuxent estuary.
Scatter Plots of Water Quality Variables
Scatter plots of variables were developed in order to determine water
quality variable linear associations. Figure 11-22 shows the expected
correlation of total phosphorus (TP) and total particulate phosphorus (TPP)
in the lower estuary. Other plots, although not shown, indicate that TPP
and chlorophyll-ja was correlated (r=0.76) as well as chlorophyll-^ and TP
(see Table 11-1). Figure 11-23 indicates the expected relation between
chlorophyll-^ and particulate carbon in the lower estuary. The highest
linear correlation of dissolved oxygen was found when regressed against the
particulate carbon and particulate nitrogen ration (r=0.62). Insight would
be enhanced and more reasonable predictive statistical models of water
quality variables could be developed if multiple linear regression models
were employed to the data set. Figures 11-24 and 11-25 show a fairly
strong nonlinear correlation between total inorganic nitrogen and
ortho-phosphorus from the 1980-1981 slack water surveys.
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Nutrient Stratification
While estuaries are predominantly characterized on the basis of their
density stratification and circulation patterns (44), predictable short-
term variability of these parameters may be important in the distribution
of salinity, dissolved oxygen, and nutrients in the water column. Haas
(45) reported that in the James, York, and Rappahannock estuaries density
stratification and homogeneity alternated within a time scale of days, with
density stratification pronounced during neap tidal periods and destratifi-
cation approximately 4 days following maximum spring tides.
Webb and D'Elia (46) found that in the York River vertical mixing
during destratification events over a 3 day period acts to replenish oxygen
in deep water and accelerates the input of benthic regenerated nutrients
into the euphotic zone. Thus water quality variables sampled on a weekly -
monthly basis may miss important transient variations in oxygen and
nutrient distributions within the estuary. Short term stratification -
destratification events correlating to spring neap tides have been observed
to a lesser degree in the Patuxent River (47,48).
In order to determine to what degree nutrient stratification may be
associated with salinity stratification, the difference (absolute value)
between surface and bottom concentrations of variables were calculated from
slack tide survey data. Table 11-2 shows correlation coefficients for
various nutrient variables. Although this is not a complete analysis of
stratification, it is a good and reliable indicator. The correlation
coefficients were obtained from least squares regression of the absolute
value of surface to bottom differences of nutrients (dependent variable)
and salinity (independent variable). Station XED4892 (mile 25.5) shows
the greatest degree of stratification. Intensive survey data indicated
stratification was controlled by tidal forces. Table 11-2 indicates NO2
+ NO3 stratification is strongly correlated with salinity stratification.
Ammonia stratification was correlated with salinity stratification at mile
30.6 (station XED9490), the same area where sediment nutrient fluxes of
NH^ are greatest. Table 11-3 shows the lease squares regression
coefficients using various nonlinear transformations of nutrients,
normalized freshwater flow. In general, there is a stronger association
between ortho-phosphorus and ammonia stratification with salinity stratifi-
cation than with NO2 + NO3. Thus nutrient stratification in an estuary
is complex and is not purely a function of salinity stratification or
freshwater inflow. Table 11-3 indicates nutrient stratification is
associated with freshwater input at Route 50. It is interesting to note
that the N:P ratio stratification correlation with salinity stratification
was highest at the mouth of the river system (XCF9575) indicating nutrient
limitations in this river reach may be dominated by transient tidal
conditions.
Nutrient stratification in the water column is not an easily quanti-
fiable process, however in order to refine the above analysis, various
transformations to the absolute value surface to bottom differences of
nutrients and salinity were made, followed by least squares regression.
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The resulting highest correlation coefficients were selected and are
presented in Table 11-3. Although no simple transformation or normali-
zation of the stratification values reveiled a consistent trend for all
variables at all stations, it can be observed that NO^ + NOj stratifi-
cation tends to be related to salinity stratification, NH3 stratification
tends to be related to salinity stratification in the upper estuary, while
the lower estuary stratification is related with a combination of salinity
normalized to freshwater inflow. Orthophosphorus in the upper estuary
shows the opposite trend in the upper estuary, i.e. nutrient stratification
may be dependent upon salinity normalized by freshwater inflow, the middle
estuary nutrient stratification tending to be dominated by salinity only
and in the lower estuary, stratification potentially dominated by salinity
normalized to freshwater inflow. The N:P Redfield ratio stratification
appears to be dominated by salinity normalized to freshwater inflow and the
lower estuary N:P ration stratification due mainly to salinity. This
simplistic analysis does however show that freshwater inflow is associated
with nutrient stratification.
Longitudinal Phytoplankton Survey Results
Two longitudinal phytoplankton surveys were conducted in order to
qualitatively determine the number of cells and species along the estuary
(see Methods Section for sampling techniques). Figure 11-26 shows the
estimated total phytoplankton cells at each slack survey station during the
July cruise and Figure 11-17 indicates the same information for the April
survey. Tables 11-4 and 11-5 are tabular presentations of the raw data.
In July both number of species and total cell counts of phytoplankton
increased substantially downstream of the Western Branch tributary. In
April, the total number of cells and species also increased, but not as
substantially as seen in the plots. Figures 11-28 and 11-29 indicate the
genera of species identified. Below Western Branch a significant increase
of cryptophytes and chrysophytes were observed as well as increases of
green algae species. At the next downstream station a peak of blue green
algae was observed as well as a diatom peak. As diatoms increase in
number, the blue greens decline substantially and cryptophytes and
chrysophytes decrease slightly. At approximately mile 30 the diatoms and
blue greens decrease substantially, and a major peak of unidentified
(1.5-2um coccoid) species dominate the total number of cells and continued
to be the predominate phytoplankton group in the 25 to 30 mile region. As
the coccoid forms, cryptophytes and chrysophytes start to decrease in the
lower estuary, dinoflagellates increase (20-25 mile region). At the mouth
of the estuary in July, the phytoplankton community was dominated by
diatoms, cryptophytes and chrysophyte species. It is interesting to note
that dlnoflagellates increased in the region where depth of the estuary
decreases below a mid-estuary sill and where salinity during the July 21
water quality slack survey indicated higher surface values, indicating
upwelling of bottom water. Salinity was also higher at the surface during
the July 23-24 water quality survey. Temperatures were lower at the
surface, supporting the view of potential upwelling related to the
dinoflagellate mid-river bloom in July.
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July surface dissolved oxygen was highest (6.2) ar. the site where
there was the maximum number of phytoplankton cells, Indicating super-
saturation (Nottingham, PXT0402). At the same location diatoms and blue
green algae reached their maximum density. Minimum surface dissolved
oxygen (4.4 mg/l) occurred at the same location where dinoflagellate
species reached their maximum intensity (see figures 11-29 and 11-30), thus
indicating stronger evidence that the phytoplankton sample collection was
producing representative phytoplankton characterization. The highest
chlorophyll-^ value (79.4 mg.m~3) also occurred at station PXT0402, near
Nottingham, where blue green algae and diatom species were dominant. A
lower estuary peak (below Benedict, XDE9401) of chlorophyll-^ corresponds
to the location where dinoflagellates were dominant. Dissolved oxygen
saturation data obtained from the intensive survey data showed supersatu-
ration at the same locations where diatoms and blue green algae were
dominant as well as the station where dinoflagellates were dominant. The
pH was greatest at the diatom and blue green dominant station and secchi
disc decreased longitudinally as the total phytoplankton cell counts
increased (see figure 7-6). Water column ammonia decreased slightly at the
locations of the dinoflagellate and diatom/blue green dominant locations
(see July 21 longitudinal plot, figure 7-11). A total particulate nitrogen
maximum in surface waters also coincided at the station with maximum cell
counts of cryptophytes, chrysophytes and unidentified coccoid species.
Dissolved organic nitrogen concentrations were substantially higher at the
same locations where blue greens, diatoms, cryptophytes, chrysophytes and
unidentified coccoid species were dominant. The highest total organic
carbon, total phosphorus and total particulate phosphorus water column
concentrations also occurred at the location In the lower estuary where
dinoflagellate, cryptophyte and chrysophyte dominant station.
The total N:P ratio calculated from data for July 21, 1980 indicated
that above Benedict, where the lower estuary bloom of dinoflagellates and
other phytoplankton species occurred, nitrogen may have been a limiting
nutrient. Nitrogen limitation was also supported by values of the Redfield
ratio (see figure 7-21, July 21, 1980). The Redfield ratio also indicates
that the upper river was phosphorus limited where blue greens, greens and
diatoms where dominant. Pheophytin-a was greatest at the stations where
blue greens, greens and diatoms where dominant. Dissolved reactive sili-
cate reached a minimum (near zero) where blue greens and diatoms reached
their maximum cell counts, i.e. Nottingham. A total solids river maximum
was observed at Nottingham and above Benedict.
It is interesting to note that the green non-filamentous algae
Scenedesmus quadricauda was found at stations PXT0490, PXT0455, and
XED9490, all located in the tidal portion of the river down to Lower
Marlboro. This species has been reported to be sixth on a list of 20
pollutant tolerant species of algae (36). In addition, the diatom genera
Nitzschla was observed in July at PXT0402, reported 6th on a list of 22
most pollutant tolerant genera of algae. During this July survey at
station PXT0402, 6 species of diatoms were tentatively identified and
Nitzchia was the least dominant species present. At the other stations
where Scenedesmus quadricauda was tentatively identified, it was never the
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most dominant species, but was most dominant at station PXT0455 where blue
green algae reached r.heir maximum density. This station was also where
blue green algal density was observed to be highest. Neither of these
types of algal cells were present at the freshwater stations (i.e. PXT0603
and WXT0045).
The April 1981 survey indicated diatoms were more dominant at the
mouth of the estuary and decreased up-estuary, reaching a minimum in the
turbidity maximum region. The dominant diatom was Rhizosolenia
fragillissima, followed by the Cyclotella genera of diatoms. The latter
genera have been reported to be a pollutant tolerant genera in freshwater
environments (Parrish, 1975). These two types of diatoms were dominant up
to approximately mile 20, where Rhizosolenia and Skeletonema costatum, a
marine diatom were the dominant diatoms. Above Benedict (XED4892)
Nltzschia species were found, but were not dominant. At the next upstream
station (XDE9490-mile 30) Cyclotella species became dominant and the
Melosira genera of diatoms were observed (also indicated as pollutant
tolerant diatoms). At station PXT0455 at Jug Bay, below Western Branch, no
marine diatoms were observed and the dominant genera were Navicula followed
by Nitzschia genera and Synedra species. This station thus showed a
dominant shift of diatom species towards pollutant tolerant species.
Euglena species, a flagellate algae genera was also found at this station
as well as the station above Western Branch (PXT0494). Above Western
Branch the Synedra genera of diatoms became dominant (another reported
pollutant tolerant freshwater diatom) followed by Navicula species. At the
freshwater stations (PXT0603, WXT0045) the dominant diatoms were the
Navicula genera followed by the Synedra genera. Thus, the small upper
river peak of diatoms were composed of reportedly pollutant tolerant
freshwater species. Without further comparative analysis it can not be
determined that these species are indicative of a polluted environment in
the upper reach of the Patuxent River. Comparison of the water column data
indicates that a silica minimum occurs at the mouth of the estuary where
diatoms were the second dominant type of algae. The most dominant algae
were cryptophytes and chrysophytes. It is also interesting to note that
the small upper river silica minimum occurred at the same station where
Figure 11-31 indicates a small upper river diatom peak.
Figure 11-31 indicates that the second dominant algae genera was a
green algae, tentatively identified as Nannochloris with maximum cell
counts at station XED4892 (mile 25). Dinoflagellates also reached maximum
density at this location. The dominant dinoflagellate at station XDE9401
and XED4892 was Katodinium rotundatum. Above station XED4892 (above
Benedict) there were essentially no dinoflagellates, indicating the source
of dinoflagellates as deeper Chesapeake Bay water. During this survey the
surface salinity was higher than the one meter depth and salinity stratifi-
cation from surface to bottom was approximately 0.1 to 0.2 ppt. In addi-
tion station XED4892 water temperature at one meter was lower. Together
these factors indicate potential upwelling phenomena in this region.
Intensive survey plots of temperature (see figure 9-2) also indicate water
column temperature was the lowest in the estuary at this location.
Cryptomonas species and microflagellates dominated the upper and lower
78
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estuary, with Cryptomonas acuta being the only fairly unique species
tentatively identified. Other than Nannochloris, the upper river green
algal maximum cell density was due to the dominance of coccoid green algae,
and the Chlorella genera, a reportedly pollution tolerant, genera of green
algae. Nannochloris was the dominant green algae observed in the PXT0603
(Rt. 50) sample and Western Branch tributary samples. It is interesting to
note that phytoplankton species and cell densities in April were at their
maximum at the same station where April zooplankton observations (funded by
the U.S. EPA) indicated maximum densities, i.e. stations PXT0455 (Jug Bay),
PXT0402 (Nottingham) and XED9490 (Lower Marlboro).
During the April phytoplankton survey, the highest chlorophyll-a
(mg.m~3) value was observed at the mouth of the estuary where diatom
densities were highest, (XCF9575) see Table 11-6.
Longitudinal Bacterial Measurements
Three longitudinal surveys were conducted in order to qualitatively
identify potential nitrification reaches in the lower river and estuarine
system. Tables 11-7 through 11-9 show the results of the water and sedi-
ment analysis as performed and described in Section 2. A major source of
NOJ is from river discharge. Sediments are a source of ammonia (NH3)
which in water become ammonium (NH^). Nitrification is defined as the
processes (bio-chemical) which provide the pathways for transformation of
ammonia to nitrate, i.e., NH^"1" to NO2- to NO3-. Two genera of
bacteria responsible for nitrification are Nitrobacter species and
Nitrosomonas species. Nitrosomonas species reduce ammonium ions (NH4+)
to Nitrite (N02~) and Nitrobacter species reduce nitrite (N02~) to
nitrate (NO3-). The number of colony forming units (shown in Tables 11-7
through 11-9) indicate the potential magnitude of these species in water
samples and sediments. During the mainstem surveys, water column samples
indicate that reduction of NH^+ to NO2" was potentially greatest at
Nottingham (PXT0402), below Western Branch, July 23-24 and August 21, 1980,
and in the lower estuary an April 20-21, 1981 (Station XDE5339). Reduction
of N02~ to N03~ by Nitrobacter species was potentially greatest in the
water column in the lower estuary (XDE2599) in July, Lower Marlboro
(XED9490) in August and above Western Branch (PXT0494) in April.
In sediments, reduction of NH^*" to N02~ by Nitrosomonas was
potentially greatest in the lower estuary (XDE5339) in July, August and
April. NO2" to NO3" reduction by Nitrobacter species in sediments was
potentially greatest at station PXT0402 (Nottingham) in July, at XED9490
(Lower Marlboro) in August and at XED4892 (above Benedict) in April. Thus
a potential for greater Nh£ to NO2 sediment reduction in the lower
estuary exists, and N0;f to NO3 reduction in the mid to upper estuary.
This data corresponds to high benthic NH^+ sediment flux in the upper
estuary observed in July and August during this study and in previous
studies (Boynton et al., 1980)(57). Trends of nitrification in the water
column are not as apparent. More detailed measurements from more than one
water column sample or sediment sample at longitudinal stations are needed
in order to verify nitrification trends as well as accuracy of measurements
made at one sampling location.
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Primary Productivity Measurements
Productivity measurements were made at six locations in the river
system as described in Section 2. At the three locations, (see figure 2-3)
data indicate that depth averaged net photosynthesis is greatest in the
upper estuary at the Selby Landing site, below Western Branch (see Table
11-10). Net photosynthesis was approximately twice as high at this loca-
tion than at Jacks Bay and a factor of 6 higher than the lower estuary
oxygen budget station at Sotterly Point. The same trend appears with gross
photosynthesis, except that Sotterly Point and Jacks Bay differs only by a
factor of 2. Respiration at Sotterly Point and Jacks Bay is approximately
the same. At Selby Landing respiration is higher by a factor of 2. Sur-
face light and dark bottle primary productivity data also show consistently
higher surface gross and net photosynthesis values as expected. Water tem-
perature is higher in this region of the river (Jug Bay and Selby Landing)
as well as higher nutrient concentrations as a result point non-point
source loads and sediment fluxes. Sediment oxygen demand was, on the
average, greater at Selby Landing than other mid-estuary stations (see
figures 5-12, 5-15 and 5-14). The variability of these measurements is
known to be high. Based upon this data the average and standard deviation
of respiration at any depth during the year from single bottle estimates
would be expected to be 9 + 13 mg -at C^.nT^.hr-1.
Productivity measurements were also made in the lower Patuxent Estuary
as part of this study by the University of Maryland, at sites shown in
figure 2-5. The location of the light and dark bottles were at different
depths than the previously described measurements, the incubation period
was shorter and triplicate bottles were suspended at 90% and 60% of surface
light insolation. The values they report are areal estimates
(0£g.m-^ .d~^) and therefore cannot be directly compared to the
previously described data. The April, 1981 Marsh Point productivity
observations were slightly higher (11.61 + .17 g O2 .m~^ • d-^) than
the other two lower estuary stations. In October, 1980 St. Leonards Creek
productivity was generally higher, and in August of 1981 St. Leonards Creek
was slightly higher. The same trends were observed for respiration
measurements. More variability was observed at the upstream station.
Table 11-11 shows the actual measurements.
D'Elia et al. (16) utilized the above productivity measurements and
the euphotic zone benthic flux data to estimate phytoplankton demand for
ammonia in the daytime. Demand was approximately 10 times greater than the
amount of ammonium in the water column (August, 1980 data). They estimated
the phytoplankton demand of 0.5 ug -at L~^, and average sediment regener-
ation of ammonium of 0.0008 g -at/square meter/day and that sediments may
supply approximately 30% of the daily phytoplankton demand, and can replace
water column storage ammonium by a factor of 2 to 3 times a day. D'Elia et
al., conclude that during this summer period additional recycling sites or
sources of ammonia must exist and hypothesize that remineralization is the
likely source of nitrogen.
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Data reported by the University of Maryland for this study also indi-
cated phytoplankton respiration was greater than benthic respiration.
Benthic respiration (sediment oxygen demand) may account for an average of
24% (range 12 - 58%) of the oxygen utilization In the subeuphotic water
column, thus less than 24% for the total water column. D'Elia et al. (16)
conclude, based upon their relatively few measurements assumptions of
strongly stratified water column conditions, that around 75% of the
observed respiration in the lower river might be partitioned to the
plankton community and 25% to benthic respiration.
Based upon the data collected for this study, gross estimates of the
turnover time (time required for total oxygen content of the subeuphotic
zone to be utilized by water column and benthic respiration) were calcu-
lated, and during periods of strong stratification appear to be approxi-
mately 1 to 4.3 days (16). This information therefore points to the need
to understand vertical mixing as well as the areal and temporal extent of
stratification In order to more realistically determine the extent of low
dissolved oxygen potential impacts on the fishery community. Data
collected from this study during the 24 hour intensive surveys suggest that
in the lower estuary, tidal forces alone may not be strong enough to
replenish subeuphotic dissolved oxygen to a level that is considered
suitable for finfish, but increased vertical mixing during wind events may
provide the energy necessary for vertical mixing in order to destratify the
water column and replenish oxygen to deeper waters in the lower estuary.
Conservative Mixing of Water Quality Variables
The identification of conservative or non-conservative mixing of water
quality variables can be addressed simplistlcally by scatter plots of a
variable versus salinity (42). It is clear that identification of
non-conservative behaviour is difficult when temporal variations of the
inputs produce changes in the residence time and ambient concentrations of
a nutrient species or water quality variable, or when complex circulation
In a particular reach of an estuary is complex and affects the ambient
concentration. This technique of identifying the conservative nature of a
variable in an estuary tends to become more difficult and tentative when
two end members are evident (43), when tributaries freshwater inputs,
topography and estuary morphology changes the longitudinal rate of dilution
or mixing. Statements regarding potential sources or sinks of nutrients
discussed below should be considered in light of the above limitations of
this simplistic analysis.
Figures 11-34 through 11-44 show plots of the 1980-1981 mean station
salinity and the respective mean water quality variable. Figure 11-34
shows total phosphorus concentrations in the upper river is diluted and may
be a potential sink in the salinity region 1-3 ppt. At approximately 8.5
ppt there appears to be a potential source of total phosphorus. At 14.5
ppt there is indication of a sink and at 15.5 ppt a potential source of
phosphorus. The surface total phosphorus plot (not shown) indicated a
stronger trend of a source of phosphorus In the lower estuary, while the
bottom mean total phosphorus versus salinity plot indicated a very strong
mid-estuary source above and below Benedict (XED4892) and XDE9401).
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Dissolved nitrate mean values indicate dilution Is fairly consistent
and the major portion of the estuary may serve as a sink of NO3, however
figure 11-34 indicates a potential lower estuary source. Plots of average
surface concentrations indicated a substantial source of nitrate at
stations XDE2599 and XDE5339 in the lower estuary, while bottom values
indicated a substantial source of nitrate at stations XDE2599 and XDE5339
in the lower estuary. Bottom mean concentrations indicate a potential
source at the mouth of the estuary, probably representing release from the
sediments.
Dissolved phosphorus (figure 11-35) is diluted in the upper estuary.
This plot indicates two end points. At the station above Benedict
(XED4892) a source of dissolved phosphorus is indicated. The surface
dissolved phosphorus plot indicated a definite source in the mid-estuary
(stations XED4892, XED9490, PXT0402), a sink at station XDE5339 and a
source at XDE2599, above Solomons. Bottom concentrations indicate a sink at
Lower Marlboro (XED9490) and a potential source above and below Benedict.
Dissolved reactive silicate shown in figure 11-35 indicates two end
points. However surface and bottom values did not indicate two end points.
The turbidity maximum region (Nottingham-PXT0402 and XED9590-Lower
Marlboro) appears to be a sink for silica. Above Benedict silica appears
to behave conservatively. Below Benedict a source of silica is indicated
(i.e. XDE9401, XDE5339 and XDE2599). Surface and bottom values indicate
the same general trend.
Figure 11-36 indicates a potential mid river source of ortho-phospho-
rus above and below Benedict. Evaluation of mean surface values indicated
a potential source above Solomons to Lower Marlboro. Bottom values
indicate the same trend extends up Nottingham with the highest source
region above Benedict (XED4892), however this station is where the
intensive surveys indicated a factor of 2-3 concentration increase of
nutrient concentrations was associated to tide stage.
Although not shown, plots of total particulate phosphorus indicated
simple dilution dominated this constituent except above Benedict (XED4892)
and above Solomons (XDE2599) a potential source was indicated. Surface TPP
indicated the same trend except a source was indicated above and below
Benedict.
The dissolved organic carbon indicates a source near Nottingham and
potentially from the Chesapeake Bay. Overall, the middle and lower estuary
may act as a sink. Bottom and surface mean values indicate the same
general trend.
Total organic carbon values (figure 11-37) indicate the opposite
trend, i.e., a potential addition or accumulation of total organic carbon.
Bottom values indicate a sink or dilution in the lower estuary.
Pheophytin-a average values follow the trend of conservative
(dilution) action. The same trend was indicated by mean bottom water
observations, while a slight sink is indicated by surface values.
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Total alkalinity and chlorides appear (figure 11-38) conservative as
expected. Figure 11-39 plots indicate higher chlorophyll-^ values at the
mouth of the estuary and uncorrected values indicate a dominant source in
the mid-estuary turbidity maximum region as expected. Bottom chlorophyll-a
values do not indicate a mid-river addition, but a lower river addition.
Figure 11-40 indicates dilution and uptake of total nitrogen in the
upper estuary and a trend for conservative dilution from the salinity
region 3 to 16 ppt. Bottom values indicated straight dilution with no
apparent uptake or source (i.e. linearity). Surface values, indicated
dilution as expected, however an upper river source above Benedict was
indicated as well as above Solomons.
Two end points of seston are indicated in Figure 11-40. This may be
due to the turbidity maximum region. The surface and bottom plots substan-
tiate the source or addition of the suspended solids is in the turbidity
maimum region of the estuary. Figure 11-41 plots shows the increasing pH
near the mouth of the estuary. Dissolved total nitrite behaves non-conser-
vatively as expected, with surface values indicating a potential source
from Chesapeake Bay, however bottom water mean values do not indicate
higher concentrations at the mouth of the estuary. Higher water column
concentrations at the surface may be indicative of remineralization.
Mean dissolved oxygen is highest at Jug Bay, the mouth of the estuary.
Dissolved oxygen 1980-1981 station averages shown in figure 11-43 indicate
the minimum average occuring below Benedict (XDE5339). This same trend is
observed for bottom average values. Surface mean values however indicate
the highest average dissolved oxygen saturation below Benedict. BOD5
plots (figure 11-42) show higher average demand above Benedict. Surface
values for lower estuary regions arp also highest above Benidict and bottom
water BOD5 is highest in the upper estuary.
Average dissolved nitrogen (figure 11-43) values indicate no source of
nitrogen from the Bay, and that the estuary serves as a potential sink for
dissolved nitrogen, however surface and bottom station means indicate a
potentially stronger trend for a source from the Chesapeake Bay or from
bottom sediments. Dissolved Ammonia is non-conservative with a general
trend of the lower estuary bottom waters providing a source of ammonia
below Benedict and above Solomons. Surface ammonia is higher at the mouth
of the estuary indicating potential water column remineralization as well
as at the Nottingham station (PXT00402). Temperature was highest above
Benidict as shown in figure 11-44.
In order to more fully understand the relation between water quality
variables and salinity, plots of concentration versus salinity of actual
survey observations were plotted instead of average values. Figure 11-45
is a plot of all chlorophyll values versus salinity. No general trend is
obvious, except occassional chlorophyll-^ values above 50 ug/1, indicating
eutrophic conditions. Chlorophyll-a, corrected for presence of pheophytin
indicate a definite trend of higher concentrations in the lower estuary in
April of 1982 during the intensive survey.
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Figure 11-46 shows the slack water chlorophyll-a surface and bottom
values in April, collected after the intensive survey, when a large diatom
bloom was evident at the mouth of the estuary. June 29, 1981 chlorophyll
values indicate much lower values at the mouth of the estuary. Figure
11-47 shows the results of the April intensive chlorophyll-a values
indicating high April, chlorophyll-a in the upper and lower estuary
reaches. During the March 19, 1981 slack survey values at the mouth of the
river were much lower, indicating that by April biological productivity
probably increased due to warmer temperatures. Alkalinity plotted against
salinity (see figure 11-49) shows the same trend as mean value plots. The
pH was much lower in the upper river, around 6.7, slightly near the
critical point for juvenile finfish survival.
Figure 11-50 would indicate that during the spring, BODtj is greatest
in the lower estuary. This same figure shows that D.O. saturation is much
higher in the lower estuary in the spring as expected.
Dissolved reactive silicate plotted against salinity for the April 27
slack survey data indicates it behaves rather conservatively in the spring,
with an indication of sources or additional input in the upper estuary.
During the March 1981 slack survey the reverse trend was apparent, i.e.
uptake of silica in the mid-estuarine region. The April 23 intensive
survey data shown in figure 11-52 indicates a source or addition of silica
in the upper estuary. In the upper reaches of the lower estuary there is
also a unique trend of uptake or a sink of silica. During the June 1981
slack survey the conservative nature of silica shows much lower concentra-
tions in the upper estuary, indicating uptake. All data shown in figure
11-53 indicates two trends of silica versus salinity in the upper estuary.
During the summer, upper river concentration appear much lower, probably
due to greater uptake by the algal community, whereas silica appears more
conservative, as expected during the late fall and early spring in the
upper river.
Figure 11-54 shows that during the early spring, there may be a source
of ammonia in the upper estuary and a sink in the lower estuary (see March
1981 data). While during June 11 slack survey bottom waters indicate a
source and in surface waters a potential sink. April 23, 1981 extensive
survey data indicate quite clearly a potential sink in the lower estuary.
The figure also shows that higher suspended solids occur in the summer as
expectd in the mid-estuary.
Figure 11-56 shows dilution and a potential sink of nitrite in the
lower estuary. This plot could also be indicative of the fact that nitrate
is being flushed out of the river as it becomes diluted with Chesapeake Bay
waters in March. Figure 11-57 shows the intensive survey data obtained on
April 23, with indication of some higher concentrations in the lower
estuary.
Figure 1L-56 also indicates a potential sink or uptake of nitrate
during the March 19 slack survey, although probably not significant. The
April 23, intensive survey data indicate nitrates have substantially
84
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increases, especially in the upper estuary. This may be a result of
increased freshwater spring loads and/or nitrification processes operating
at a faster rate in the river. Between these two survey dates the total
nitrogen and total dissolved nitrogen did not appear to change considerably
(see figure 11-58).
It is obvious from these plots that the ability to discuss potential
sources or sinks in somewhat limited, however general trends in the estuary
can be observed. Mean value plots may not reflect actual conditions in the
river and may be misleading.
More detailed nitrifying bacteria measurements would be useful in
determining cell count estimates. This type of data, in conjunction with
the longitudinal water quality variables, would help discriminate the
degree to which longitudinal trends of nitrification could be discerned.
Nutrient and Silica Relationships
In order to determine ^ny gross relations between dissolved reactive
silicate and mean values of water quality variables from mainstem stations
for surface and bottom values were plotted against silica.
Plots of total phosphorus versus silica indicates that in surface
water, a close to linear relationship exists. This trend was not apparent
in bottom waters from the mainstem stations above 5 mg/1 silica. No
obvious relation was observed between dissolved phosphorus and silica,
however a fairly strong linear relation existed between orthophosphorus and
silica.
A fairly strong linear relation also exists for total particular
phosphous and silica. These linear relations are indicative of the
relation between uptake of phosphorus and silica by phytoplankton with
higher TPP indicative of greater blomass. The strength of the linear
relation between TPP and orthophosphorus was stronger with silica than with
any other nutrient variable. Mean salinity and chlorides plotted against
silica indicated that at approximately 3 ppt salinity (turbidity maximum
region) a large sink of silica exists. This region is an area of higher
primary productivity.
A linear trend between silica and chlorophyll-^ and pheophytin-£ was
indicated, indicating higher chlorophyll-a at low silica concentrations.
This indicates that silica may become a limiting nutrient.
Tables 11-13 and 11-14 show the results of univariate linear relations
between water quality variables, salinity and silica from calculated mean
station values during 1980-1981. It can be seen that the degree of rela-
tion depends on depth of water sample taken and whether all station data
are included in the analysis. These results (r^) can be used to help
determine which variables appear to act conservative.
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Gross Station Statistical Summaries
Tables 11-15 and 11-16 shows the univariate statistics for all data
collected during the slack water and intensive surveys in 1980-81. This
has been included for future comparison and for comparing other estuaries
in the Chesapeake Bay Region. Tables 11-17 and 11-18 gives the univariate
statistics comparing the data for the 1980-1981 period by depth. Note that
mid-depth samples were taken in the upper tidal river section of the
Patuxent system. Table 11-19 shows the average concentrations in the
salinity regions from 0-3, 3.1-10 ppt, and in the region greater than 10
ppt salinity. "
Potential Sources Indicated by Ambient Water Quality Data
Historical ambient data that may indicate potential sources of total
phosphorus and nitrate was presented by Flemer, et.al., 1970. Space-time
domain plots, figures 11-60 through 11-63 are taken from Flemer et al.,
(30) 1970 and indicate that total phosphorus concentrations in the lower
estuary are highest during the summer (1969). During this period a greater
amount of phosphorus may be transported out of the system, however a
conclusive statement cannot be made without hydrographic measurements.
This data also supports the view of sediments acting as a source in the
late 1960's.
Figure 11-61 indicates that nitrate is higher during the spring and
winter in the lower estuary, and transport of nitrate from the estuary to
Chesapeake Bay may be greatest during this period.
The space-time domain plot shown in figure 11-64 shows the slack water
data for orthophosphorus collected during this study. Both the 1969 and
1980 plots modified after D'Elia et al., 1981 (16) indicate higher summer
values of phosphorus. These values also tend to occur when the estuary
dissolved inorganic sediment flux appears to be greatest (see Tables 11-20,
11-21). During the spring of 1981, higher lower estuary water concentra-
tions of orthophosphorus were observed. This could be due to transport of
bottom orthophosphate our of the river, but a conclusive statement cannot
be made. The April, 1981 longitudinal phytoplankton survey indicated a
marine diatom and dinoflagellate bloom in the mid and lower estuary at this
same time. Figure 11-65 indicates higher bottom water concentrations of
ammonia during summer months, coinciding with higher sediment flux measure-
ments shown in Tables 11-20 and 11-21. During the 1980-81 fall, winter and
spring period low surface and bottom ammonium was observed, indicative of
lower sediment flux measurements and water column remineralization (due to
reduced microrganism activities in the sediments and water column).
Figures 11-61 and 11-66 indicate similar trends of nitrate in the river
during the spring of 1970 and spring of 1981. Surface values during
1980-1981 are however higher. Figure 11-67 shows summer 1981 chlorophyll-a
values similar to those reported in 1970 by Flemer, et.al. (30). Figure
11-68 indicates, as expected, low dissolved oxygen in the lower estuary
during the summer months, especially in the bottom waters when sediment
oxygen demand tends to be highest (see figures 11-69, 11-70, and Table
11-22).
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Sediment oxygen demand measurements are shown in Table 11-22. These
measurements indicate sediments can be a significant source of oxygen
demand. In fact, average SOD for the river appears to be
3.28g02m~^d~^ or an average daily river demand estimated to be near
721,600 lbs/day. This demand will vary depending upon location and time of
year. The impact upon the river's dissolved oxygen budget and biological
productivity will depend upon water column stratification. Data collected
by the University of Maryland (16) and Biospherics, Inc. (31) are similar
(see figures ,11-69 and 11-70). The Patuxent estuary has been cited to have
exhibited some of the highest SOD measurements reported in coastal
ecosystems. Figure 11-71, modified after D'Elia et al. 1981 (16) shows
relative SOD measurements reported for a variety of marine ecosystems. The
Patuxent River SOD average appears to exhibit somewhat higher values than
other values, however, the substantially larger range of SOD may be a
function of a greater number of stations and time periods where data has
been collected, compared to other marine ecosystems.
Figure 11-72 indicates the relative magnitude of ammonium flux in the
lower estuary. Tables 11-20 and 11-21 show the actual values and the range
of ammonium sediment flux in the middle and upper Patuxent estuary.
Although the flux changes from location and by season the data indicate
average flux out of the sediments around 235 mg-at-m^hr~l• Thus
ammonium flux from the sediment to the water column exhibit an extreme
influence upon productivity in the basin.
Other data presented in this section also indicate the potential
sources of chemicals to the estuary as viewed by the simple mixing
diagrams, i.e. concentration versus salinity plots.
Plots are presented which indicate dilution as a function of salinity
(see figures 11-34 to 11-58). Potential sources of chemicals can be
inferred from these figures, however due to the extreme variability of
water column measurements, statements regarding sources of chemicals from
these conservative mixing diagrams are limited. These figures do however
show that the region of the turbidity maximum has higher concentrations for
many water quality variables. Plots of bottom water concentrations
indicate that lower river values can be higher than mid-river values,
however this is probably related to sediment flux and the Chesapeake Bay
does not appear to be a source of chemicals to the estuary (see Section 11
for a more detailed description) from the analyses. Flux measurements are
needed at the mouth of the estuary to verify this estimate.
87
-------
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53. McCarthy, J. J., Taylor, W.R., and M.E. Loftus. Significance of
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56. Rowe, G. T., C.H. Clifford, and K.L. Smith, Jr. Nutrient
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65. Mihursky, J. A., and W.R. Boynton. Review of Patuxent Estuary Data
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J. Mar. Res. Vol. 1. 1940.
93
-------
APPENDIX A
FIGURES AND TABLES FOR METHODS; SECTION 2
94
-------
Table 2-1
Patuxent Survey Date And Date Of Spring And Neap Tides
Month
Survey Date
Spring Tides
Neap Tides
June, 1980
25*
12
6
28
20
July
21
12
5
24-25 (intensive)**
28
27
20
August
20
10
3
26
18
September
15
9
1
24
17
October
16
9
1
23
17
November
13
7
15
22
29
December
4
7
15
21
29
March, 1981
19
6
12
20
28
April
21
4
11
23-24 (Intensive)
27
19
27
May
14 ..
3
10
18
26
June
11
2
9
29
17
24
July
16
1
16
8
30
30
24
August
13
15
7
29
22
* slack surveys
** intensive surveys
95
-------
Table 2-2
Patuxent River Slack Tide and Intensive Water Quality
Survey Monitoring Stations (Mid Channel)
Station
Number
Station
Description
Nautical
Miles Upstream
From Mouth
La ti tude
Longitude
XCF9575
2.2 km E.N.E. of F1 "3" at 27 ft. depth
0.1
381930.3
0762233.8
XOE2599
1000 yds. S of Black Daybeacon
"1" at 23 ft.depth.
9.6
382231.4
0763006.8
XDE5339
Mid Channel of Jack Bay,
sand pit~N.E. of Sandgate
13.9
382530.7
0763607.5
XDE9401
Mid Channel, 0.3 mi N.N.E. of Long Pt.
19.9
382926.7
0763952.5
XDE4892
M1d channel on transect heading
115° form Jacks Creek
25.5
383455.1
0764052.7
XED9490
Mid channel opposite wharf at
Lower Marlboro
30.6
383929.9
0764102.8
PXT0402
Mid channel at Nottingham
35.2
384235.5
0764206 .3
PXT0455
Western Shore at Jackson Landing
40.6
384 651.1
0764255.8
PXT0494
Mid channel upstream side of
Md. Route 4 bridge, near Waysons Corner
42.9
384836.9
0764245.3
PXT0603
Upstream side of U.S. Rt. 50
Bridge at USGS Gauge
54.2
385719.6
0764139.9
WXT0045
At Water St. Bride in Upper Marlboro
--
3848 51.0
0764504.2
*750632
At discharge weir of Western Branch WWT
plant
* Data not collected by ANSP during 24 hour surveys
-------
Table 2-3
Patuxent River Slack Tide Water Quality
Survey Monitoring Stations (lateral Stations)
Station
Number
Station
Description
Nautical Miles
Upstream from
Mouth
Channel Transect
Latitude Longitude Side Number
vo
XCF8763 500 yds. E. of Hogg Point 0.9
22 ft. depth
XCF9958 2200 yds. N.E. of Drum Pt., 1.1
22 ft. depth
XDE2586 1,000 yds. S.E. of Sotterley 9.8
Wharf, 8 ft. depth
XDE2898 500 yds. of Marker "1" at 9.4
St. Leonards Creek, 20 ft.
XDE454 3 300 yds. N. of Mouth at Roslin 14.1
Creek, 12 ft. depth
XDE5352 700 yds. S. of Mouth of Ben Creek. 13.8
12 ft. depth
XDE9699 100yds. N. of Marker G 19.95
"23". 9 ft. depth
XDE9603 800 yds. E. of marker G "23", 19.8
8 ft. depth
XED4891 500 yds. E.S.E. of rrouth of Jacks 25.3
Creek, 7 ft. depth
XED4894 App. 900 yds. N. of Marker R 25.4
"25" near Cedarhaven, 6 ft. depth
381843.9 0752552.4 west
381953.5 0762400.2 east
382213.8 0763048.4 west
382303.0 0763004.1 east
382501.1 0763610.1 west
382552.6 0763554.8 east
382839.1 0764200.0 west
382938.5 0763928.« east
383447.2 0764106.6 west
383447.1 0764037.6 east
2
2
3
3
4
4
5
5
-------
Table 2-4 Times at which samples were collected at each station and
substation for each slack water survey on the Patuxent River. Also listed
are predicted times of minimum current at five locations in the Patient
River. SBF {slack before flood] refers to the predicted time of minimum
current before flooding began at each of the five locations. SBE (slack
before ebb) refers to the predicted time of minimum current before ebbing
began at each of the five locations.
station
date
SGF
date
SBE
date
SBF
date
SBE
date
SBF
location
time
time
time
time
time
time
time
* time
time
time
6/25/60
7/21
7/28
8/20
9/15
XCF8763
0820
0932
1030
0925
1230
XCF9575
0833
1005
1040
0945
1250
XCF9958
0920
1044
1120
1030
1330
Drum Point
0858(c)
1012
1109
1037
1335
XDEZ586
0944
1126
1152
1050
1410
XDE2599
0955
1150
1200
1105
1415
XDE2898
1023
1226
1230
1130
1445
Broomes Island
0916
1035
1127
1100
1353
XDE4543
0856
1250
1300
1155
1505
X0E5339
0915
1305
1310
1200
1515
XDE5352
1014
1332
1341
1230
1540
Sheridan Point
0944
1059
1155
1124
1421
XDE9699
1034
0930
1030
1100
1220
X0E9401
1047
0955
1037
1115
1255
X0E9603
1122
1032
1102
1145
1325
Benedict Bridge
0932
1129
1143
1153
1409
XEC4891
1201
1115
1126
1210
1352
XED4892
1208
1125
1132
1220
1400
XED4894
1235
1149
1152
1240
1415
XED9490
1258
1218
1212
1306
1435
Lyons Creek
Wharf
1103
1145
1314
1210
1540
PXT04Q2
1331
1300
1244
1345
1523
PXT0455
1230
0918
0920
1225
1555
PXT0494
1600
1135
1025
1030
1435
UXT0045
1330
1020
1105
1135
1345
PXT0603
1445
1225
1150
0937
1215
(a) - date of survey
(b) - sample collection time
(c) - time of predicted minimum current at given location
98'
-------
Table 2-4 (cont.) Times at which samples were collected at each station and
substation for each slack water survey on the Patuxent River. Also listed
are the NOAA predicted times of minimum current at five locations in the
Patuxent River. SBF (slack before flood) refers to the predicted time of
minimra current before flooding began at each of the five locations. SEE
(slack before ebb) refers to the predicted time of minimum current before
ebbing began at each of the five locations.
station date(a)
SBE
date
SBF
date
SBE
date
SBF
date
SBE
location time(b) time
time
time
time
time
time
time
time
time
10/16
11/13
12/4
3/19
4/21
XCF8763 0800
1002
1125
1216
—
XCF9575 0810
1019
1135
1240
—
XCF9958 0833
1045
1200
1255
--
Drum Point
0905(c)
1203
1310
1419
1118
X0E2586 0913
1115
1230
1322
1200
XDE2599 0930
1130
1250
1340
1215
X0E289& 0955
1155
1305
1400
1247.
Broomes Island
0928
1221
1333
1442
1136
XDE4543 1 01 7
1215
1335
1430
1315
X0E5339 1028
1230
1348
1450
1327
XDE5352 1050
1255
1416
1505
1352
Sheridan Point
0952
1249
1357
1506
1204
XDE9699 0855
1130
1230
1330
1000
XDE9401 0900
U40
1245
1335
1025
XDE9603 0925
1205
1330
1400
1059
Benedict Bridge
1021
1237
1426
1535
1152
XED489I 0945
1225
1355
1425
1128
XED4892 0953
1230
1405
1430
1137
XE04894 1 012
1250
1425
1455
1202
XE09490 1030
1307
1447
1505
1223
Lyons Creek Wharf
1038
1408
1443
1552
1323
PXT0402 1055
1355
1520
1535
1304
PXT0455 0840
1040
1130
1716
1017
PXT0494 1020
1205
1245
1548
1105
PXT0603 1115
1345
1430
1446
1240
WXT0045 0935
1300
1345
1336
1150
(a) - date of survey
(b) - sample collection time
(c) - time of predicted minimum current at given location
99
-------
Table 2-4 (cont.) Times at which samples were collected at each location and
substation for each slack water surbey on the Patuxent River. Also listed
are the NOAA predicted times of minimum current at five locations in the
Patuxent River. SBF (slack before flood) refers to the predicted time of
minimum current before flooding began at each of the five locations. SBE
(slack before ebb) refers to the predicted tine of minimum current before
oKK-irn " -
station
date(a)
SbE
date
SBE
date
SBE
date
SBE
date
SBF
location
time(b) time
time
time
time
time
time
«
time
time
time
4/27
5/14
6/11
6/29
7/16
XCF8763
0756
1035
0939
0700
0911
XCF9575
0821
1100
0949
0715
0929
XCF9958
0902
1150
1022
0735
1010
Drum Point
0906(c)
1236
1058
0839
1121
XDE2586
0927
1215
1050
0800
1037
XDE2599
0938
1235
1103
0815
1055
XDE2898
1007
1305
1124
0835
1121
Broomes Island
0929
1259
1121
0857
1139
XDE4543
1044
1325
1204
0900
1143
XDE5339
1058
1345
1212
0915
1158
XOE5352
1126
1405
1233
0935
1219
Sheridan Point
0953
1325
1145
0925
1207
X0E9699
0820
1158
1030
0801
1015
XDE9401
0830
1205
1037
0807
1027
XDE9603
0855
1224
1055
0825
1054
Benedict Bridge
1022
1352
1214
0913
1155
XED4891
0916
1242
1128
0850
1121
XE04892
0925
1246
1132
0855
1130
XE04894
0950
1302
1145
0909
1150
XED9490
1010
1317
1215
0930
1214
Lyons Creek Wharf
1039
1409
1231
1044
1326
PXT0402
1040
1340
1242
1020
1253
PXT0455
0900
1429
1314
1045
1255
PXT0494
1000
1305
1235
1145
1150
UXT0045
1100
1215
1137
1230
1050
PXT0603
1140
1130
1037
0945
1000
(a) - date of survey
(b) - sample collection time
(c) - time of predicted minimum current at given location
100
-------
Table 2-4 (cont.) Times at which samples were collected at each station and
substation for each slack water survey on the Patuxent River. Also listed
are the NOAA predicted times of minimum current at five locations in the
Patuxent River. SBF (slack before flood) refers to the predicted time of
minimum current before flooding began at each of the five locations. SBE
(slack before ebb) refers to the predicted time of minimum current before
ebbing began at each of the five locations.
stations
.date(a)
SBF
date
SBF
location
Time(b)
Time
Time
Time
7/30
8/13
XCF8763
0826
0845
XCF9575
0848
0910
XCF9958
0916
0940
Drum Point
0955(c)
0926
XDE2586
0939
1020
XDE2599
0952
1037
XDE2898
1015
1110
Broomes Island
1013
0944
XDE4 543
1040
1139
XDE5339
1050
1155
XDE5352
1108
1230
Sheridan Point
1041
1012
X0E9699
0920
0957
XDE9401
0936
1005
XDE9603
1000
Benedict Bridqe
1029
1000
XE04891
1028
1105
XED4892
1034
1112
XED4894
1054
1130
XED9490
1118
1152
Lyons Creek Wharf
1200
1121
PXT0402
1152
1223
PXT0455
1225
1235
PXT0494
1110
1120
WXT0045
1040
1040
PXT0603
0940
0925
(a) - date of survey
(b) - sample collection time
(c) - time of predicted minimum current at given location
101
-------
Table 2-5 Predicted Times Of Minimum Current At Each Of Five Locations During
The July 1980 And April 1981 24-hour Intensive Mater Quality Surveys.
Date Location
July 24, 25, 1980
SBF*
SBE**
SBF
SBE
SBF '
Drum Point
0833
1300
0850
0208
0919
Broomes Island
0851
1323
1908
0231
0937
Sheridan Point
0819
1347
1936
0255
1005
Benedict Bridge
0907
1416
1924
0324
0953
Lyons Creek Wharf
1038
1433
2055
0341
1114
April 23, 24, 1981
SBE
SBF
SBE
SBF
SBE
Drum Point
0546
1258
1801
2325
0632
Broomes Island
0609
1316
1824
2343
0655
Sheridan Point
0633
1344
1848
0011
1719
Benedict 3ridge
0702
1332
1917
2359
0748
Lyons Creek Wharf
0719
1503
1934
0130
0805
(*) - predicted time of slack before flood
(**) - predicted time of slack before ebb
102
-------
Table 2-6 Intensive Water Quality Survey Sampling Schedule, July 24-25, 1980 And April 23-24, 1981 ,
Samples Were Collected At Approximately 2 Hour Intervals Over A 24 Hour Period
Station
Current
(a) Stage velocity/
Depth height direction
Wind
0.0., pH, temp.,
temp, and humidity Light
salinity barometer Secchi penetration
Water
chemistry (1)
XCF9575
sur yes
yes
yes yes yes
yes
mid yes
no
no
bot ' yes
yes
yes
Surface, mid-depth and
bottom
current
velocities also west and east sides of river
XDE2599
sue meter yes
yes
yes yes yes
yes
ml d yes
no
no
bot yes
yes
yes
Surface, mid-depth and
bottom
current
velocities also at west and east sides of
river
XDE5339
sur yes
yes
yes yes yes
yes
mid yes
no
no
bot yes
yes
yes
Surface, m1d-depthand
bottom
current
velocities also at west and east sides of
river
X0E9401
sur yes
yes
yes yes yes
yes
mid yes
no
no
bot yes
yes
yes
Surface, mid-depth and
bottom
current
velocities also at west and east sides of
ri ver
XED4892
sur yes
yes
yes yes yes
yes
mid yes
no
no
bot yes
yes
yes
Surface, mid-depth and
bottom
current
velocities also at west and east sides of
river
XED9490
sur meter yes
yes
yes yes yes
yes
mi d yes
no
no
bot yes
yes
yes
(a) general description of measurement depth, I.e. surface, bottom or mid-depth.
-------
Table 2-6 (continued) Intensive Water Quality Survey Sampling Schedule, July 24-25, 1980 And April 23-24,
1981, Samples Were Collected At Approximately 2 Hour Intervals Over A 24 Hour Period
Station
Depth
Stage
height
Current
velocity/
direction
D.O., pH,
temp, and
salinity
Wind
temp
humidity
barometer
SeccM
Light
penetration
Water
chemistry (1)
PXT0402
sur
yes
yes
yes
yes
yes
yes
mid
yes
no
no
bot
yes
yes
yes
PXT0455
sur
yes
no
yes
yes
yes
no
mid
yes
yes
yes
bot
yes
no
no
PXT0494
sur
no
no
yes
yes
yes
no
mid
no
yes
yes
bot
no
no
no
WXT0045
sur
x.s. flow
no
yes
yes
yes
no
mid
each 2 hrs
yes
yes
bot
no
no
PXT0603
sur
gauge
no
yes
yes
no
mid
yes
yes
bot
no
no
(1) Total chlorophyll-a and phaeophytln-a
B0D5
TOC/DOC: TOC through September 1980, DOC after September 1980
COD: Stations PXT0402.PXT0455, PXT0494, WXT0045, PXT0603, and 750632 only; not tested 1n 1981.
TPP unflltered
TPP filtered
Total ortho-phosphate
N02-N filtered
N03-N filtered
NH3-N filtered
TPN unfiltered
TPN filtered
Total suspended solids
SI02
Total alkalinity
-------
Table 2-7 Slaclt Water Surveys Sampling Schedule Without lateral Locations.
Hind,
Current
D.O..
pH» temp..
Stage
velocity/
temp.
and humidity
Light
Water
Fecal
Station
height
direction
salinity barometer Secchl penetration
chemistry (2)
collform {3}
60020
Chlorides (4)
XDE9575
sur no
yes
yes
yes yes
yes
yes
yes
yes
yes
mid
yes
no
no
no
no
no
bot
yes
yes
yes -
yes
yes
yes
Surface, mid-depth
and bottom
current
velocities also at west and east sides of
river
XE02599
sur meter
yes
yes
yes yes
yes
yes
yes
no
no
mid
yes
no
no
no
no
no
bot
yes
yes
yes
yes
no
no
Surface, mid-depth
and bottom
current
velocities also at west and east sides of
river
XDE5339
sur no
yes
yes
yes yes
yes
yes
yes
yes
yes
mid
yes
no
flo
no
no
no
bot yes
yes
yes
yes
yes
yes
Surface, mid-depth
and bottom
current
velocities also at west and east sides of
river
XDE9401
sur no
yes
yes
yes yes
yes
yes
yes
no
no
mid
yes
no
no
no
no
no
bot
yes
yes
yes
yes
no
no
Surface, mid-depth
and bottom
current
velocities also at west
and east sides of
river
XED4892
sur no
yes
yes
yes yes
yes
yes
yes
yes
yes
mid
yes
no
no
no
no
no
bot
yes
yes
yes
yes
yes
yes
Surface, mid-depth
and bottom
current
velocities also at west
and east sides of
r1 ver
XEQ9490
sur meter
yes
yes
yes yes
yes
yes
yes
no
no
mid
yes
no
no
no
no
no
bot
yes
yes
yes
yes
no
no
PXT0402
sur no
yes
yes
yes yes
yes
yes
yes
yes
yes
mid
yes
no
no
no
no
no
bot
yes
yes
yes
yes
yes
yes
-------
Table 2-7 (continued) Slack Water Surveys Sampling Schedule Wthout Lateral Locations.
Station
Depth
Stage
height
Current
velocity/
direction
0.0., pH,
temp, and
salinity
Wind,
temp.,
humidity
barometer
Secchl
Hqht
penetration
Water
chemistry (2)
Fecal
coll form (3)
B0D20
Chlorides (4)
PXT0455
sur
no
yes
no
yes
yes
yes
no
no
no
no
mid
yes
yes
yes
yes
no
no
bot
yes
no
no
no
no
no
PXT0494
sur
no
yes
no
yes
yes
yes
no
no
no
no
mid
yes
yes
yes
yes
no
no
bot
yes
no
no
no
no
no
WXT0045
sur
measure
no
yes
yes
yes
no
no
no
no
mid
tnstan-
yes
yes
yes
no
no
bot
twneous
no
no
no
no
no
PXT0603
sur
gauge
no
yes
yes
yes
no
no
no
no
mid
yes
yes
yes
yes
yes
bot
no
no
no
no
no
750632
no
no
pH only
no
no
no
24 hr
no
no
no
flow
composite (5)
(1) June 25, July 28, August 20, September 15, October 16, November 13, December 4, 198(1; March 19, April 27, Hay 14, June 11, June 29, July 30 and
August 13, 1981.
(2) Total chlorophyll-a and phaeophytln
BOD 5
TOC/DOC: TOO through September 1980, DOC after September 1980.
COD: Stations PXT0402. PXT045S, PXT0494, HXT0045, PXT0603, and 750632 only; not tested In 1981.
TPP unflltered N02-N filtered TPN unfiltered S'O?
TPP filtered N03-N filtered TPN filtered Total alkalinity
Total ortho-ohosphate NH3-N filtered Total suspended sol Ids
(3) Not tested in 1981
(4) Not tested after September 1980.
(5) Not tested for total chlorophyll-a, phaeophytin-a and fecal collforms.
-------
Table 2-8 Slack Water Survey Sampling Schedule. With Lateral Stations. July 21. 1980 And ftprll 21, 1981
Station
Depth
Stage
height
Current
velocity/
direction
D.O., pH,
temp, and
salinity
Wind,
temp,
humldlty
barometer
Secchl
Llqht
penetration
Hater
chemistry (1)
Fecal
coliform (2)
60020
Chic
XCF8763
sur
no
yes
no
no
no
no
yes
yes
no
no
west
mid
yes
no
no
no
no
no
no
no
no
bot
yes
no
no
no
no
yes
yes
no
no
XCF9575
sur
no
yes
yes
yes
yes
yes
yes
yes
yes
yes
mid
yes
no
no
no
no
no
no
no
no
bot
yes
yes
no
no
no
yes
yes
yes
yes
XCF9958
sur
no
yes
nc
no
no
no
yes
yes
no
no
east
mid
yes
no
no
no
no
no
no
no
no
bot
yes
no
no
no
no
yes
yes
no
no
X0E2586
sur
no
yes
no
no
no
no
yes
yes
no
no
west
mid
yes
no
no
no
no
no
no
no
no
bot
yes
no
no
no
no
yes
yes
no
no
XDE2559
sur
meter
yes
yes
yes
yes
yes
yes
yes
no
no
center
mid
yes
no
no
no
no
no
no
no
no'
bot
yes
yes
no
no
no
yes
yes
no
no
XDE2898
sur
no
yes
no
no
no
no
yes
yes
no
no
east
mid
yes
no
no
no
no
no
no
no
no
bot
yes
no
no
no
no
yes
yes
no
no
XDE4543
sur
no
yes
no
no
no
no
yes
yes
no
no
west
mid
yes
no
no
no
no
no
no
no
no
bot
yes
no
no
no
no
yes
yes
no
no
-------
Table 2-8 (continued) Slack Water Survey Sampling Schedule. With Lateral Stations. July 21. 1980 And April 21. 1981
Station
Depth
Stage
height
Current
velocity/
direction
0.0., pH,
temp, and
salInity
Wind,
temp,
humldlty
barometer
Secchi
Liaht
penetration
Water
chemistry (1)
Fecal
collform (2)
B0020
Chlorides (3)
XDE5339
sur
no
yes
yes
yes
yes
yes
yes
yes
yes
yes
center
mid
yes
no
no
no
no
no
no
no
no
bot
yes
yes
no
no
no
yes
yes
yes
yes
XDE5352
sur
no
yes
no
no
no
no
yes
yes
no
no
east
mid
yes
no
no
no
no
no
no
no
no
bot
yes
no
no
no
no
yes
yes
no
no
XDE9699
sur
no
yes
no
no
no
no
yes
yes
no
no
west
mid
yes
no
no
no
no
no
no
no
no
bot
yes
no
no
no
no
yes
yes
no
no
X0E94O1
sur
no
yes
yes
yes
yes
yes
yes
yes
no
no
center
mid
yes
no
no
no
no
no
no
no
no
bot
yes
yes
no
no
no
yes
yes
no
no
X0E96O3
sur
yes
no
no
no
no
yes
yes
no
no
east
mid
yes
no
no
no
no
no
no
no
no
bot
yes
no
no
no
no
yes
yes
no
no
XED4891
sur
no
yes
no
no
no
no
yes
yes
no
no
west
mid
yes
no
no
no
no
no
no
no
no
bot
yes
no
no
no
no
yes
yes
no
no
XED4892
sur
no
yes
yes
yes
yes
yes
yes
yes
yes
yes
center
mid
yes
no
no
no
no
no
no
no
no
bot
yes
yes
no
no
no
yes
yes
yes
yes
XED4894
sur
no
yes
no
no
no
no
yes
yes
no
no
east
mid
no
yes
no
no
no
r.o
no
no
no
bot
yes
ro
no
no
no
yes
yes
no
no
-------
Table 2-8 (continued] Slack Water Survey Singling Schedule. With lateral Stations. July 2\, 1960 And April 21, 1981
Sutlcn
Depth
Stage
height
Current
velocl ty
direction
0.0., pH
0.0a, PH.
salinity
Wind.
tenp.
ba ro meter
SeccM
Liqht
penetration
Hater
chemistry (1)
Fecal
col ifcrm (2)
B0D20
Chic
XE09490
sur
«ter
yes
yes
yes
yes.
yes
yes
yes
no
no
center
mid
yes
no
na
¦ no
RO
no
no
no
no
bot
yes
yes
no
no
no
yes
yes
no
no
PXT0402
sur
no
yes
yes
yes
yes
yes
yes
yes
yes
yes
center
mf d
yes
no
no
no
no
no
no
no
no
bot
yes
yes
no
no
no
yes
yes
yes
yes
PXT0455
sur
no
yes
no
yes
yes
yes
no
no
no
no
center
mid
yes
yes
no
no
no
yes
yes
no
no
bot
yes
no
no
no
no
no
no
no
no
PKT0494
sur
no
yes
no
yes
yes
yes
no
no
no
no
center
mid
yes
yes
no
no
no
yes
yes
nor
no
bot
yes
no
no
no
no
no
no
no
no
WXT0045
sur
measure
no
yes
yes
yes
no
no
no
no
center
mid
Instan
instan-
yes
no
no
no
yes
yes
no
no
bot
taneous
no
no
no
no
no
no
no
no
PXT0603
sur
gauge
no
yes
yes
yes
no
no
no
no
center
mid
yes
no
no
no
yes
yes
yes
yes
bot
no
no
no
no
no
no
no
no
750632
rw
no
pH only
no
no
no
24 hr
no
no
no
flew
composite (4)
(1) Total chlorophyll-a and phaeophyt1n-a
BODS
TOC/OOC: TOC through September 1980, DOC after September 1180
COB: Station! PXT04C2, PKT0455, PKTQ494, VHTM45, PJ>T'"J6rJ3, and 750632 cnl^; rot tested 1n 19fl
(2) Not tested in 1981
(3) Not tested after September 1980
(4) Not tested for total chlorophyll-a,
phaeophj/t in-a arid fecal coliforms.
TPP filtered
Total ortho-phosphate
N02-N filtered
N03-N filtered
NH3-N filtered
TPH tinflHened
TPrj filtered
Total suspended solids
S!02
Total alkalinity
-------
Table 2-9 Analytical Procedures for Patuxent Estuary Program.
Water Quality Variable
Reference
Total persulfate phosphorus
Total persulfate nitrogen
Nitrate-nitrite, mgN/1,
cadmium reduction
Nitrite, mgN/1
Ammonia, mgN/1, Phenate
COD, over digested and
titrated
Organic carbon
Alkalinity, methyl orange or
pH meter to 4.5 or from
cresol green methyl red
Chlorides, mg/1
Solids, nonfilterable
Ortho-phosphorus, mg/1
ascorbic acid
B0D5 and 20
SI02, dissolved
Fecal coliform, MPN
Chlorophyll and phaeophytin
D'Elia, Steudler and Corwin, 1977.
D'Elia, Steudler and Corwin, 1977.
EPA, 1974.
EPA, 1974.
EPA, 1974.
EPA, 1979.
Dohrman, 1976 and 1979.
Standard Methods, 14 Edition, 1975.
EPA, 1979.
EPA, 1974 and 1979.
EPA, 1974.
Standard Methods, 14 Edition, 1975.
Technicon AA industrial method 7-68 W
and 8-68 W.
EPA, 1978.
Stricklans and Parsons, 1972.
110
-------
Table 2-10 sample preservation and holding time for estuary program during
1980. During 1981 nitrite, nitrate, ortho-phosphorus, ammonia, total
phosphorous, total nitrogen, silica and organic carbon were frozen until
analysis.
water quality variable
container
preservative
maximum
holding
time
Alkalinity, unfiltered
P
Cool
4°C
14 days
i
Ammonia, filtered
p(a)
Cool
4°C, H2S04pH<2
28 days
\
B0D5 and 20, unfiltered
P
Cool
o
o
48 hours
COD, unfiltered
P
Cool
4°C, H2S04pH<2
28 days
Total persulfate
nitrogen, filtered and
unfiltered
P
Cool
4°C, H2S04pH<2
28 days
Nitrate-nitrite, filtered
P
Cool
4°C, H2S04pH<2
28 days
Nitrite, filtered
P
Cool
-P*
o
o
48 hours
Organic carbon, unfiltered
P
Cool
4°C, HCLpH<2
28 days
Ortho-phosphorus, filtered
and unfiltered
P
filter, cool 4°C
48 hours
Silica, filtered
P
Cool
-P*
o
o
28 days
Solids, nonfilterable
P
Cool
4°C
7 days
Fecal coliform, unfiltered
P (sterile)
t Cool
-P*
o
o
6 hours
Total persulfate
phosphorus, filtered
and unfiltered
P
Cool
4°C, H2S04ph 2
28 days
Chlorophyll-a
P
Cool
4°C, dark
8 hours
Phaeophytin-a
P
Cool
4°C, dark
8 hours
Chlorides, unfiltered
P
none
required
28 days
(a) -polyethylene
111
-------
Table 2-11 Standard stability and/or frequency of standard for estuarine
water quality program preparation.
Water Quality Variable
Stability and/or
frequency
Reference
Ammonia
monthly
EPA, 1979
Total persulfate nitrogen
monthly
EPA, 1979
Nitrate, nitrite
6-months
EPA, 1979
Organic carbon
every run
Dohrman, 1976 and
1981
Ortho-phosphorus
monthly
EPA, 1979
SI02
every run
Technicon AA
industrial method
7-68W and 8-68W
Total persulfate
phosphorus
monthly
EPA, 1979
112
-------
Table 2-12 Precision and Accuracy for Ammonia Nitrogen Estuary Program.
Precision
Sampl e
N
Mean
Std. Var
C.V.
A
7
.098
.005
¦5%
B
7
. .036
.001
4%
C
7
.199
.002
<1%
D
7
.077
.003
4%
E
7
.032
.003
10%
F
7
.081
.001
<1%
G
8
.054
.001
2%
H
8
.021
.002
10%
I
7
.081
.003
4%
J
7
.040
.004
10%
K
7
.466
.006
1%
5% Average
A precision check based on the replicate analysis of 19 samples
yielded a mean C.V.
of 4% with a range of 0
to 12%.
Accuracy
Sample
N
Mean
Std. Var.
C.V. % Recovery
A saline
5
.172
.003
2% 100
B fresh
7
.127
.001
1% 112
E saline
7
.116
.002
2% 106
F fresh
7
.123
.001
<1% 104
6 saline
7
.095
.002
2% 103
H fresh
7
.063
.001
2% 105
I saline
7
.235
.002
U 100
Using an EPA quality control
samnle the percent recovery was 102%.
113
-------
Table 2-13 Precision and accuracy for filtered total persulfate nitrogen
estuary program.
Precision
Sample
N
Mean
Std. Var.
C.V.
A
12
.580
.020
3%
B
12
.844
.090
11%
C
12
.432
.050
12%
D
12
.688
.040
5%
E
7
2.886
.093
3%
F
7
.849
.038
5%
G
6
.356
.041
12%
H
6
.315
.021
6%
I
6
.153
.034
22%
J
9
.501
.091
18%
10% Average
A precision check based on the replicate analysis of 33 samples
yielded a mean C.V. of 8% with a range of 1 to 32%.
Accuracy
Sample
N
Mean
Std. Var.
C.V.
% Recovery
A saline
12
1.409
.016
1%
106
B saline
12
1.597
.023
1%
101
C fresh-
12
1.219
.017
1%.
102
saline
D fresh
12
1.532
.096
6%
107
J saline
9
1.404
.202
14%
111
Using two EPA quality control samples the percent recovery was 119%
for one, with a magnitude of 5 mg/1, and 95 and 96% for a second,
which was run twice, with a magnitude of approximately 4.0 mg/1.
114
-------
Table 2-14 Precision and Accuracy for Ortho-phosphate Estuary Program
Precision
C.V.
13%
5%
2%
4%
7%
6%
3%
18%
15%
4%
16%
8%
3%
8% Average
a precision check based on the replicate analysis of 19 samples
yielded a mean C.V. of 2% with a range of 0 to 12%.
Accuracy
Sample
N
Mean
Std. Var.
C.V.
% Recovery
B saline
7
.097
.002
2%
100
C fresh
6
.094
.001
1%
104
D saline
7
.085
.002
2%
105
E fresh
7
.053
.001
1%
102
F saline
7
.052
.001
1%
102
G saline
7
.065
, .001
1%
102
K saline
7
.084
.001
1%
99
Using an EPA quality control sample the percent recovery was 94%.
Sample
N
Mean
Std. Var.
A
6
.015
.002
B
7
.019
.001
C
8
.052
.001
D
7
.043
.002
E
7
.012
.001
F
8
.011
.001
G
8
.025
.001
H
5
.007
.001
I
5
.006
.001
J
7
.030
.001
K
7
.005
.001
L
5
.010
.001
M
5
.024
.001
115
-------
Table 2-15 Precision for total persulfate nitrogen and phosphorus for
estuary program.
Precision for unfiltered total persulfate nitrogen
Sample
N
Mean
Std. Var.
C.V.
A
6
.571
.043
8%
B
6
2.204
.025
1%
C
10
.678
.037
6%
D
5
.271
.008
3%
E
6
3.412
.174
5%
F
6
4.357
.155
4%
A precision check based on the replicate analysis of 17 samples
yielded a mean C.V. of 6% with a range of 0 to 22%.
Precision for unfiltered total persulfate phosphorus
Sample
N
Mean
Std. Var.
C.V.
A
5
.676
.009
1%
B
5
.121
.121
3%
C
6
1.590
.113
7%
D
4
.577
.009
2%
E
4
.600
.020
3%
3% Average
A precision check based on the replicate analysis of 24 samples
yielded a mean C.V. of 9% with a range of 1 to 46%.
116
-------
Table 2-16 Precision and accuracy for filtered total persulfate
phosphorus.
Precision
Sample
N
Mean
Std. Var.
C.V.
A
12
.038
.007
19%
B
12
.140
.010
7%
C
12
.027
.005
17%
D
12
.023
.005
23%
E
7
.200
.008
4%
F
7
.383
.004
1%
G
5
.432
.058
14%
H
6
.354
.037
10%
I
9
.058
.005
8%
J
9
.033
.010
31%
13% Average
A precision check based
on the replicate analys
is of 28 samples
yielded a mean
C.V. of <
)% with a
range of 1 to
30%.
Accuracy
Samp!e
N
Mean
Std. Var.
C.V.
% Recovery
A saline
12
.184
.009
5%
95
B saline
12
.282
.020
8%
98
C fresh-
12
.179
.017
9%
97
saline
D fresh
12
.179
.017
' 9%
99
J saline
9
.402
.015
4%
93
Using two different EPA quality control samples the percents
recovery were 104 and 101.
117
-------
Table 2-17 Precision and Accuracy for Silicate Estuary Program.
Precision
Sample
N
Mean
Std. Var.
C.V.
A
7
6.213
.344
6%
B
7
2.081
.084
4%
C
7
.642
.035
5%
D
7
1.986
.010
<1%
E
7
.868
.031
4%
F
7
2.715
.068
2%
G
7
1.624
.045
3%
H
6
1.333
.035
3%
4% Average
A precision check based on the replicate analysis of 31 samples
yielded a mean C.V. of 7% with a range of 0 to 33%.
Accuracy
Sample
N
Mean
Std. Var.
C.V.
% Recovery
C saline
7
1.402
.018
1%
101
D sali ne
7
, 6.009
.032
<1%
102
E saline
1
4.949
—
—
102
G saline
7
. 9.487
.076
1%
100
H saline
9
9.299
.073
1%
101
No EPA quality control standard was available for silicate.
118
-------
Table 2-18 Precision and accuracy for alkalinity for estuary program.
Precision
Sample
N
Mean
Std. Var.
C.V.
A
8
9.4
.3
3%
B
8
72.2
1.0
1%
C
4
71.4
2.9
4%
D
6
68.9
1.4
2%
E
7
52.3
.4
1%
F
5
88.2
1.0
1%
2% Average
A precision check based on the replicate analysis of 41 samples
yielded a mean C.V. of 1% with a range of 0 to 1%.
Accuracy
During the 1981 study year arid the 1982 intensive, alkalinity
was analyzed employing a phototitrator which detects a preset
colormetric end point at pH 4.5 using methyl orange indicator.
Throughout titrations, a periodic check of the end point indicated
a mean pH of 4.5 + 0.14 with a range of 4.4 to 4.6 and a C.V.
of 3%. The remainder of the alkalinities were determined by
titrating to an end point of 4.5 which was measured with a
Corning Model 610 pH Meter.
119
-------
Table 2-19 Precision and Accuracy for Nitrite Nitrogen Estuary Sample Program.
Precision
Sample
N
Mean
Std. Var.
C.V.
A
7
.007
.001
14%
B
7
.005
.0003
8%
C
7
.005
0.000
0%
D
7
.005
0.000
0%
E
7
.058
.001
1%
F
8
.028
.002
7%
G
8
.027
.003
13%
H
8
.007
.001
12%
I
7
.017
.001'
4%
J
7
.081
.001
1%
K
6
.004
.001
.19%
L
5
.136
.002
1%
7% Average
A precision check based on the replicate analysis of 19 samples
yielded a mean C.V. of 4% with a range of 0 to 35%.
Accuracy
Sample
N
Mean
Std. Var.
C.V.
% Recovery
D saline
7
.013
0.000
0%
100
F saline
7
.071
.002
2%
106
G fresh-
7
.065
.002
3%
99
sal ine
H saline
7
.051
.001
2%
109
I saline
7
.060
.001
1%
107
J saline-
7
.118
.001
1%
100
fresh
No EPA gual
ity control
standard
was available for nitrite nitrogen.
120
-------
Table 2-20 Precision and Accuracy for Nitrate Nitrogen Estuary Program.
Precision
, Sample
N
Mean
Std. Var.
C.V.
A
7
.061
.002
3%
B
8
.102
.001
1%
C
8
.034
.001
4%
D.
4
.350
.002
<1%
E
4
.081
.001
1%
F
4
.024
.001
3%
G
8
.076
.003
5%
H
8
.033
.001
4%
I
5
.051
.002
5%
J
6
.102
.006
6%
K
6
.015
.003 ,
18%
L
6
.227
.004
2%
4% Average
A precision check based on the replicate analysis of 38 samples
yielded a mean C.V. of 1% with a range of 0 to 18%.
Accuracy
Sample
N
Mean
Std. Var.
C.V.
% Recovery
C saline
4
.133
.004
3%
120
D fresh
4
.404
.002
<1%
100
G saline
7
.282
.008
3%
103
H fresh
7
.240
.002
1%
103
J saline
7
.501
.005
1%
101
Using an EPA quality control sample the percent recovery was 101%
121
-------
Table 2-21 Precision for suspended solids arid dissolved organic carbon estuary program.
Precision for suspended solids
Sample N Mean Std. Var. C.V.^
A 5 .0334 .0023 7%
B 4 .0459 .0077 17%
12% Average
A precision check based on the replicate analysis of 33 samples
yielded a mean C.V. of 10% with a range of 0 to 70%.
Precision for total dissolved organic carbon
£» Sample N Mean Std. Var. C.V.
A 5 2.4 .3 12%
B 7 5.0 .2 4%
C 5 4.1 .2 5%
D 4 6.7 .4 6%
7% Average
A precision check based on the replicate analysis of 74 samples
yielded a mean C.V. of 8% with a range og 0 to 33%
-------
Figure2-3 Water quality sampling locations in the lower
Patuxent Estuary, conducted by University of Maryland, 1980-
1981.
123
-------
Figure 2-4 Sampling locations and scheme for longitudinal
biological and benthic measurements in the Patuxent River,
conducted by Biosph_erics. ..lac... 1980-1981.
124
-------
Figure 2-5 Benthic oxygen demand and nutrient-flux measurement
stations conducted by University of Maryland, 1980-81.
1 25
-------
SEDIMENT
SEALING FLANGE
TEST CHAMBER Surface Volume-0 105
Tempereture 18.51 .4°C Control
17 81 7°C Experimental
_ 6.0
I "
0 2 JO
1 0
- "< I X <
—/J' J -j— COMlftOL DO
' ~o*k_ I 1 W ®0 WUOE
f" l>- MSMNOMTM
\*A
1.0 2 J)
TtME< HounJ
CENTRIFUGAL
CIRCULATION PUMP
NON - TOXIC EPOXY
COATING
PURGE VALVE
ASSEMBLY
SPRING
CHAMBER LID
SILICONE BALL
Figure 2-6 Diagram of Sediment Oxygen Demand Chambers
designed for measurements taken for this study by Biospherics
Inc, 1981.
126
-------
Table 2-22 Methods and Preservation
Techniques Use For Monitoring Subwatersheds Chemical Export
Parameters
EPA
Method
Analysis*
Holding times
Prior to
1/30/81
Holdinq times
after 1/30/81**
Ammonia (filtered)
Nitrate & Nitrite (filtered)
Total nitrogen (Kjeldahl)
(filtered and unfiltered)
Total phosphorus (filtered
and unfiltered)
Orthophosphate (filtered)
bod5
BOD30
Total Suspended Solids
Total Organic Carbon
Chemical Oxygen Demand
Alkalinity
350.1
353.2
351.2
365.1
365.1
405.1
405.1
160.2
415.1
410.2
310.2
24 hrs.
24 hrs.
24 hrs.
24 hrs.
24 hrs.
24 hrs.
24 hrs.
7 days
24 hrs.
7 days
24 hrs.
28 days
28 days
28 days
28 days
48 hrs.
48 hrs.
48 hrs.
14 days
28 days
28 days
14 days
** CFR Vol. 44, Part 136, December 3, 1979
127
-------
NON-POINT SOURCE
COMPOSITE SAMPLE
(5 gallon polyethylene)
SAMPLE SPLITTING
COOL 40 c I
ORTHOPROSPATE
SAMPLE
(100 ml)
FILTER .4511
TOC SAMPLE
(125 ml gle&s)
no
OO
ANALYSIS 48 BRS.
EPA METHOD 365 .1
BODs eutd BODji
SAMPLE
fl-llter poly)
TSS 6 ALKALINITY
SAMPLE
(1-liter poly)
HCl, pH<2
ANALYSIS 28 DAYS
EPA METHOD 415.1
ANALYSIS 49 BRS.
SPA METHOD 405.1
TKN, TP, COD
SAMPLE
(1-liter poly)
HzSOs, pH<2
»Hj, ROi+ WOj, TKN, TP
SAMPLE
(1-liter poly)
f
ANALYSIS 14 DAYS
EPA METHOD
160.2 (TSS)
310.2 (ALKALINITY)
ANALYSIS 28 DAYS
EPA METHODS
351.2 (TKN)
365.2 (TP)
410.2 (COD)
FILTER
.45m
RlSOn, pH<2
ANALYSIS 28 DAYS
EPA
METHODS
351
.2 (TKN)
365
.2 (TP)
350
.1 (NH,)
353
.2 (NO2 + NOjJ
1. ALL SAMPLES MAINTAINED DURING COLLECTION, DELIVERY AND UNTIL FINAL ANALYSIS AT 4° C.
2. BODi AND BOD to SAMPLES INCLUDE SAMPLES COLLECTED DURING BOTH POINT SOURCE AND RIVER SURVEYS.
Figure 2-7 Non-point source watershed sample collection and analysis scheme
-------
APPENDIX B
FIGURES AND TABLE FOR SECTION 3
129
-------
LAND UTILIZATION
PATUXENT
19S0 1955
LEGEND'• USE
I 960
1965
I 97 5
I 960
FOREST
PASTURE
USE
YEAR
Figure 3-1 Patuxent River Estimated Land Utilization from 1950-1980,
(provided by EPA, Chesapeake Bay Program).
130
-------
POPULATION PROJECTIONS
Figure 3-2 Population projections for the Patuxent River Basin Developed
in 1969, from Maryland Department of State Planning, 1969, (from reference
19)
131
-------
1000-
900-
800-
700-
600'
500-
400-
PRINCE GEORGES ,
MONTGOMERY
ANNE ARUNDEL
300-
25
10-1 1
1980 '85 '90 '95 2000 2005
Figure 3-3 Current Year Population Estimates to the year 2000, developed
by Maryland Department of State Planning, 1981 (from reference 20).
-------
Table 3-1
Estimated Percent Increase of Population from 1980-2000
for Patuxent River Basin Counties*
County
% Increase
Anne Anjndel
30
Calvert
78
Charles
50
Howard
84
Montgomery
8.5
Prince George's
10
St. Mary's
40
* Estimated from Projections Prepared by Maryland
Department of State Planning, July, 1981.
Table 3-2 Comparison of the 1969 Population Projections for the year 1980*
1969 Estimate Approximate
County for 1930 (1) 1980 Reported (2) Difference
Calvert
25,500
34,644
+9,144
St. Mary's
58,000
59,836
+1.896
Carroll
60,000
—
Howard
72,000
118.575
+46.575
Anne Arundel
430.000
370,774
-59,226
Montgomery
640,000
579,047
-60,953
Prince George's
760,000
665,075
-94,925
Charles
—
72,746
—
Seaward Population
375,000
265,850
-109,150
(1) From FWPCA, 1969, The Patuxent River, Water Quality Management
Technical Evaluation, Working Document No. 31. reference 18
(2) Obtained from Maryland Department of State Planning, 1981. reference 19
133
-------
Table 3-3
Existing (1980) and Projected (2000)
Waste Water Flows in the Patuxent River Basin
Projected Year
Facility Name
Existing Flow (mgd)
2000 Flow (mgd)
Maryland City
0.59
2.7
Patuxent
3.6
7.2
Ft. Meade
2.4
3.6
Savage
7.8
18.3
Bowie
2.5
3.3
Horsepen
0.33
1.5
Parkway
5.1
7.5
Western Branch
11.9
23.7
Maryland House of Correction
0.8
(Abandoned)
TOTAL
35.02
67.8
Reference: Office of Evnironmental Programs, Md. Department of Health
and Mental Hygiene, Draft Nutrient Control Strategy, Patuxent
River, August 1981. (reference 21).
134
-------
APPENDIX C
FIGURES PRESENTING PHYSICAL CHARACTERISTICS
SECTION 4
135
-------
o
o
o
o
Figure 4-1 Patuxent river drainage area and cumulative drainage area.
136
-------
o
o
o
u->
Figure 4-2. Estimated crossectional area arid cumulative crossectional
area (square yards) for the Patuxent Estuary.
137
-------
o
o
o
o
Figure 4-3 Mean low water width and cumulative estimated water width for
the Patuxent Estuary.
138
-------
o
o
Figure 4-4 Mean low water volume and cumulative volume in the Patuxent
estuary.
139
-------
o
o
C3
O
o
to
Figure 4-5 Water surface area and cumulative water surface area in the
Patuxent estuary.
140
-------
o
o
o
o
Figure 4-6 Hydraulic depth and cumulative hydraulic depth in the Patuxent
estuary.
141
-------
1
PATUXENT RIVER 1980
30WIE, MD
U\l
Oj
0-00
61 .00
122-00 183-00
DAY
244.00
305-00
.366. 00
PATUXENT RIVER
BOWIE, MD
96
(1020
0-00
61 .00
122-00 183-00
DAY
Figure 4-7Freshwater inflow (cubic feet per second) during the study period 1980-1981 at the USGS gauge
Rt. 50, USGS station 01594440.
-------
PATUXENT RIVER
BOWIE, MD
MONTH
Figure 4-8 Patuxent River mean monthly flow from historical data and for water
year 1980.
143
-------
Distance from mouth in nauticol miles
Distance from mouth in nautical miles
Figure 4-9 Schematic diagram of net non-tidal volume transport of (a) the
estimated three-layer flow system in the Patuxent estuary and (b) the two
layer flow system in the Patuxent estuary, from Owen, W., 1969(24).
144
-------
Distance from mouth in nautical miles
Distance from mouth in nautical miles
Figure 4-10 Patuxent Estuary 24 hour longitudinal velocity component average
for (a) June 23-28, 1952 and (b) December 3-7, 1952, from Owen, W., 1969
(24).
145
-------
-5
i i i i i ii
5cm/s
i i i
-o.to -010
OLtO IMTI
Figure 4-11 Patuxent River velocity profiles obtained from moorings during
this study (a), (b) and (c) during 1952, as reported by Owen, 1952, and the
vertical salinity profile reported by Owen (d).
146
-------
V
(nso)
1 3
nautical miLt
Figure 4-12 Location of current meter moorings conducted during this study
by Boicourt, 1981 and by CBI, 1952 as reported by Owen, 1952.
147
-------
PATUXENT RIVER
NAUTICAL MILE
Figure 4-13 Patuxent River observed and statistically estimated
functions of the salinity profile for 1980-1981.
148
-------
Figure 4-14 Estimated average longitudinal fraction of
freshwater and Chesapeake Bay water in Patuxent Estuary.
PATUXENT RIVER
o
149
-------
o
o
PATUXENT RIVER
DEVELOPED FROM
DNR BATHYMETRIC
SURVEY AND AVERAGE
FRESHWATER INFLOW
TOTAL DAYS = 315
0-00 9-00 18-00 27.00
NAUTICAL MILE
36.00
45.00
Figure 4-15 Estimated flushing time of the lower Patuxent River.
150
-------
APPENDIX D
ILLUSTRATIONS OF BOX MODELS
SECTION 5
151
-------
Table 5-1
Estimated Yearly Rainfall Loads To The Patuxent
Basin And Mater Surface From Bulk Precipitation Measurements
Loading Water Surface
Water Quality Rate Basin Load Load
Variable (Ib/acre/in.) (ton/yr) (ton/yr)
TOC 32.143E-03 231 10.0
TP 38.571E-03 278 12.0
TKN 36.429E-03 262 11.3
N02+N03 139.524E-03 1005 44.0
152
-------
3.83 X 105 lbs. (5.0%) Western Branch WWTP^
?'f§ •'
Net Exchange is
16.05 X 105 lbs. (20.9%)
from C. Bay
to the Estuary
<_n
u>
Atmosphere 1.13 X 1 05 1 bs . (1.5%)
Fluvial Sources Above Rt. 50
Avg. Freshwater Inflow 21 .23 X 105 lbs
(27 7%)
Storm Events 3.42 X 105 lbs. (4.5%)
Fluvial Sources Below Rt. 50 K
Avg. Freshwater Inflow 4.89 X 10-5 lbs.
(6.4%)
Storm Events 5.43 X 105 lbs. (7.1%)
Sediment Flux
Upper River 2.02 X 105 lbs. (2.7%)
Lower River 18.56 X 10^ lbs. (24.2%)
Figure 5-1 Patuxent Estuary Total Nitrogen Budget. Total Estimated input sources
are approximately 7,660,000 pounds for a seven month period (April thru October).
Average estuary concentration was 1.34 mg/1. The two largest sources were sediment
flux at 26.9% and fluvial Inflow at 45.7%.
-------
1.41 X 105 lbs. (4.8%) Western Branch WWTPi
Atmosphere 0.89 X 105 lbs. (3.V
Net Exchange is
10.12 X 105 lbs. (34.6%)"**
from C. Bay
to the Estuary
on
-P*
Fluvial Sources Above Rt. 50
Avg. Freshwater Inflow 13.
97 X 105
(47.8%)
Storm Events 1.06 X 105 lbs. (3.
l- Fluvial Sources Below Rt. 50
^ Avg. Freshwater Inflow 1 .62 X 105 lbs
u (5.6%)
Storm Events ] ,68 X 10b lbs. (5.7%)
y
Sediment Flux
Upper River
Lower River
-1 .98 X 105 lbs. (-6.8%)
0.46 X 105 lbs. (1 .6%)
Figure 5-2 Patuxent Estuary Dissolved NO2 + NO3 Budget. Total estimated input sources
are approximately 2,920,000 pounds for a seven month period (April thru October). Average
estuary concentration was 0.76 mg/1. The fluvial discharge was the largest source at 62.7%.
-------
0.68 X irr lbs. (1.7%)
Western Branch WWTP
Atmosphere 0.12 X 10 lbs. (0.3%)
-
•.w/ _•
•||.v
JCfr*. . . •
Net Exchange is
6.60 X 105 lbs. (16.0%)
from C. Bay
to the Estuary
tn
cn
_ Fluvial Sources Above Rt. 50
Avg. Freshwater Inflow 5.67
X 105 lbs
(13.8%)
Storm Events 0.33 X 10^ lbs. (0.8%)
Fluvial Sources Below Rt. 50
Avg. Freshwater Inflow q.38
Storm Events
0.53
,(°
X 1 05 1
X 105 lbs
9%)
bs. (1 .3%)
Sediment Flux c
Upper River 8.74 X 105 lbs. (21.2%)
Lower River 18.1 X 105 lbs. (44.0%)
Figure 5-3 Patuxent Estuary Dissolved NH^ Budget. Total estimated input sources
are approximately 4,115,000 pounds for a seven month period (April thru October).
Average estuary concentration was 0.24 mg/1. The sediment flux was the largest
source of ammonia at 65.2%.
-------
0.65 X 10 lbs. (3.
Western Branch WWTP]
cn
cr>
Net Exchange is
0.45 X 105lbs. (2.7%)
from C. Bay
to the Estuary
Atmosphere 0.25 X 105 lbs. (1.5%)
V* : .V
i
1
i.
¦
r
1
f
Fluvial Sources Above Rt. 50 (.
Avg. Freshwater Inflow 3.46 X 10 lbs
Storm Events 2.62 X
Fluvial Sources Below Rt. 50
(20.7%)
103 lbs.
(15.7%)
_5 ,L
c (4.9%)
Storm Events 4.1 6 X 1 05 lbs. (24.
Sediment Flux
Upper River 0.56 X 105 lbs. (3.3%)
Lower River 3<76 x 105 ^ bs # (22.5%)
Figure 5-4 Patuxent Estuary Total Phosphorus Budget. Total estimated input sources
are approximately 1,670,000 pounds for a seven month period (April thru October).
Average estuary concentration was 0.17 mg/1. The two largest sources were from
fluvial inflow at 66.1% and sediment flux at 25.8%.
-------
0.31 X 105 lbs. (4.4%) Western Branch WWTPs^
Atmosphere 2400 lbs. (0.3%)
Net Exchange is
¦0.03 X 105 lbs. (-0.4%)
to C. Bay from
the Estuary
-"nI
"V".' ¦ ¦ -' P?'• . .• •
vfP/';'¦ ;'.V
4
y
i
¦
T
mmm
.W-i'i-c-s?W Vi'/-1',"
f
Fluvial Sources Above Rt. 50
Avg. Freshwater Inflow 2.23 X 10^ lbs.
(31.3%)
Storm Events 7,200 lbs. (1.0%)
Fluvial Sources Below Rt. 50
Avg. Freshwater Inflow 10,300 lbs.
Storm Events 11,500 lbs. (1.6%)
(1.4%'
Sediment Flux c
Upper River 0,56 X 10^ lbs. (7.7%)
Lower River 3.76 X 105 lbs. (52.7%)
Figure 5-5 Patuxent Estuary Dissolved Ortho-phosphorus Budget. Total estimated input
sources are approximately 715,400 pounds for a seven month period (April thru October).
Average estuary concentration was 0.06 mg/1. The major sources of orthophosphorus were
from sediment flux at 60.4% and fluvial input at 35.3%.
-------
APPENDIX E
STATISTICAL ANALYSES OF NON-PGINT SOURCES
SECTION 6
158
-------
7 7®
G FARM
Z FARM
fV-T.-SP _
ANNA POLIS
Figure 6-1 General Location of Patuxent River Basin Subwatersheds
monitored for chemical export during storm events.
1.59
-------
Table 6-1
General Location And Description Of Patuxent River Subwatershed Monitoring Sites
Subwatershed Station No.
Land Use
Acres(estimated) Province
Patuxent Park BAW0006
Deale A ZEC0007
Deale B
Z Farm
G Farm
CAB0018
ZEB0005
ZED0001
Forested
Agri cultural
(corn and tobacco)
Agricultural
(corn and tobacco)
Agricultural
(field corn and pasture)
Agricultural
(field corn and pasture)
144
300
1,300
55
34
Coastal
Coastal
Coastal
Piedmont
Piedmont
-------
G farm station
Figure 6-2 Soils map of G-Farm and Z-Farm subwatersheds monitored
for chemical export during storm events.
161
-------
Table 6-2
Soil Survey Data And Interpretations For Piedmont Subwatersheds
Z-Farm
Mapping Unit Soil Name Hydrologic Group Slope(%)
GlA Glenelgloam B G-3
G1B2 Glenelgloam B 3-8
(moderately eroded)
G1C2 Glenelg loam B 8-15
(moderately eroded)
GnB2 Glenville silt-loam C 3-8
(moderately eroded)
MlB2 Manor loam B 3-8
(moderately eroded)
M1C2 Manor loam B 8-15
(moderately eroded)
G-Farm
G1B2 Glenelg Doam B 3-8
(moderately eroded)
GnB2 Glenville silt loam C 3-8
(moderately eroded)
MtB2 Mt. Airy Channery loam A 3-8
(moderately eroded)
MtC2 Mt. Airy Channery loam A 8-15
(moderately eroded)
MtC3 Mt. Airy Channery loam A 8-15
(severely eroded)
MtE Mt. Airy Channery loam A 25-45
162
-------
Deo I A
station
Deale B
station
scale 1>'12pOO
10S™
1000 feet
Figure 6-3 General map of Deale A and Deale B subwatersheds.
-------
Table 6-3
Estimated Peak Discharges Using SCS Curve Number
Methodology At Z-Farm And G-Farm For Comparative
Site Description.*
Storm Estimated Peak Discharge Runoff Rainfall
(cfs) (in.) (in.)
frequency probabili ty
(yr) (%) G-farm Z-farm G-farm Z-farm
1
100
6.8
20
0.23
0.5
2.6
2
50
13.1
33
0.44
0.83
3.2
5
20
27.1
56.9
0.91
1.46
4.2
10
10
42.6
80
1.43
2.04
5.1
25
4,
51.9
97.1
1.74
2.49
5.6
50
2
65.9
115
2.21
2.96
6.3
100
1
84.6
144
2.84
3.7
7.2
*Developed by Howard County Soil Conservation District, 1981 for this study.
164
-------
Table 6-4
Approximate Land Utilization (1981) For Z-Farm And
G-Farm Subwatersheds Monitored For Chemical Export
In The Patuxent River Watershed
Land Utilization/
G-Farm
Z-Farm**
Tillage Practice
(acres)
(acres)
Alfalfa
4
21.9
Barley/soybeans and sorghum
11
16.3
Corn
11
22.1
Homestead
2
1.3
Pasture (permanent)
6
10.8
Hay (timothy)
1.8
Countoured
23.7
No till
11
3
Stripped
15
N.M.T.*
6
12.1
Row
16.3
* None or minimum tillage
** These figures are not additive due to double cropping
165
-------
Table 6-5
Patuxent River Latitude And Longitude Description
Of The Sampling Site And Rain Gauges
Site
Monitoring
Site
Raintall
Gauge
Patuxent Park
Deale A
Deale B
Z-Farm
G-Farm
384617/764304
384729/763938
384723/763858
391514/770215
391819/770452
384613/764355
(Croom Vocational School)
384730/763919
(R-Farm)
384813/763846
(C-Farm)
Same
Same
166
-------
Table 6-6
Patuxent River NPS Chemical Export (lbs/acre) - All Stations
Variable
Mean
Standard
Error
Standard
Deviation
Median
Maximum
Minimum
B0D5
.1152
.0347
.29
.0413
2.1408
.0017
B0D30
.2856
.0922
.8701
.0994
7.705
.0027
TSS
12.171
4.607
46.982
.6065
447.047
.0019
NO 2
3.833E-4
.994E-4
4.333E-4
2.098E-4
14.805E-4
. 194E-4
N03
.0038
.0013
.0058
.0019
.0256
.194Ef4
N02N03
.0145
.003
.0292
.0049
.1677
.924E-4
NH3
.0054
.0019
.0199
.0009
.1882
.194E-4
TKN
.0342
.0104
.1086
.0059
.94T
.80ZE-4
TKND
.0097
.0024
.0248
.0033
.2355
.401E-4
TPHOS
.0413
.018
.1887
.0018
1.8408
.427E-4
TPHOSD
.0012
.0004
.0046
3.325E-4
.048
.1 E-4
DP04
8.699E-4
3.595E-4
36.489E-4
2.013E-4
36.762E-4
.049E-4
TOC
.4167
.0949
.9956
.0839
6.3766
6.676E-4
COD
1.5853
.4575
4.7982
.2473
34.644
.002
ALKIN
.1052
.019
.1937
.0526
1.3191
.002
-------
Table 6-7
Patuxent River NPS Chemical Export (lbs/acre) - All Agricultural Sites
Variable
Mean
Standard
Error
Standard
Deviation
Median
Maximum
Minimum
B0D5
.1399
.0461
.3328
.0417
2.1408
.0017
B0D30
.3458
.1293
1.0264
.0994
7.7050
.0027
TSS
16.0075
6.3991
55.0472
.6065
447.0470
.0019
NO 2
.2181E-4
.0746E-4
.2585E-4
•1818E-4
.9865E-4
.0194E-4
N03
.0048
.0020
.0070
.0024
.0256
.0194E-4
N02N03
.0181
.0040
.0328
.0058
.1677
.1582E-4
NH3
.0068
.0026
.0231
.8050E-4
.1882
.0194E-4
TKN
.0420
.0140
.1260
.0058
.9410
.0802E-4
TKND
.0112
.0032
.0287
.0034
.2355
.0401E-4
TPHOS
.0541
.0245
.2199
.0018
1.8408
.0427E-4
TPHOSD
.0014
5.991E-4
.0054
3.632E-4
.0480
0.100E-4
DP04
.0010
4.900E-4
.0042
2.013E-4
.0364
0.067E-4
TOC
.4975
.1283
1.1473
.0873
6.3766
6.676E-4
COD
1.9572
.6230
5.5650
.2390
34.6439
.0020
ALKIN
.1269
.0258
.2236
.0588
1.3191
.0022
-------
Table 6-8
Chester River NPS Chemical Export (lbs/acre) - Patuxent Park (forested)
Variable
Mean
Standard
Error
Standard
Deviation
Median
Maximum
Minimum
B0D5
.0440
.0105
.0444
.0397
.1663
.0037
B0D30
.1398
.0287
.1463
.0980
.4656
.0092
TSS
2.7080
1.6528
9.0530
.5712
49.8805
.0092
NO 2
6.665E-4
2.044E-4
5.408E-4
6.015E-4
.0014
0.243E-4
N03
.0019
8.254E- 4
.0022
.0012
.0059
0.728E-4
N02N03
.0034
8.888E-4
.0043
.0010
.0140
0.924E-4
NH3
.0018
4.120E-4
.0023
.0010
.0102
0.243E-4
TKN
.0132
.0040
.0218
.0065
.1164
1.943E-4
TKND
.0057
.0010
.0060
.0031
.0233
1.458E-4
TPHOS
.0071
.0039
.0212
.0019
.1164
1.652E-4
TPHOSD
7.319E-4
2 .015E-4
.0011
2.602E-4
.0056
0.352E-4
DP04
4.453E-4
1.565E-4
8.282E-4
1.790E-4
.0036
0.049E-4
TOC
.2010
.0497
.2723
.0743
1.2636
.0058
COD
.5934
.1602
.8773
.3061
4.3230
.0185
ALKIN
.0489
.0067
.0363
.0408
.1590
.0020
-------
Table 6-9
Chester River NPS Chemical Export (lbs/acre) - Deale A Watershed (agricultural)
Variable
Mean
Standard
Error
Standard
Deviation
Median
Maximum
Minimum
B0D5
.1993
.1159
.4915
.0619
2.1408
.0104
B0D30
.5125
.3299
1.5822
.1168
7.7050
.0027
TSS
11.6310
4.3804
23.1791
.6454
93.2722
.0019
N02
1.462E-4
0.354E-4
0.792E-4
1.541E-4
2.151E-4
0.194E-4
N03
.0026
.0015
.0033
.0017
.0082
0.194E-4
N02N03
.0223
.0077
.0406
.0043
.1677
6.940E-4
NH3
.0089
.0058
.0333
5.721E-4
.1882
0.194E-4
TKN
.0658
.0327
.1850
.0039
.9410
1.166E-4
TKND
.0128
.0072
.0411
.0027
.2355
0.777E-4
TPHOS
.0375
.0416
.0824
.0026
.3206
0.427E-4
TPHOSD
9.704E-4
2.171E-4
.0012
5.546E-4
.0048
0.233E-4
DP04
6.5000E-4
1.527E-4
8.223E-4
4.075E-4
.0030
0.194E-4
TOC
.4889
.2032
1.1496
.1070
5.5380
.0042
COD
2.3349
1.1793
6.6712
.2481
34.6440
.0058
ALKIN
.1229
.0468
.2475
.0390
1.3025
.0022
-------
Table 6-10
Chester River NPS Chemical Export (lbs/acre) - Deale B Watershed (Agricultural)
Variable
Mean
Standard
Error
Standard
Deviation
Median
Maximum
Minimum
B0D5
.0950
.0424
.1849
.0346
.7361
.0043
B0D30
.2403
.1009
.4941
.0813
2.2089
.0143
TSS
26.1250
16.7109
86.8323
.3171
447.0470
.0020
N02
3.084E-4
1.416E-4
3.470E-4
2.180E-4
9.865E-4
0.201E-4
NO 3
.0072
.0038
.0092
.0045
.0256
4.211E-4
N02N03
.0187
.0055
.0256
.0110
.1104
5.362E-4
NH3
.0054
.0027
.0146
8.497E-4
.0736
0.201E-4
TKN
.0335
.0142
.0752
.0070
.3872
0.802E-4
TKND
.0115
.0036
.0192
.0040
.0894
0.401E-4
TPHOS
.1018
.0680
.3570
.0015
1.8408
0.596E-4
TPHOSD
9.743E-4
2.949E-4
.0016
4.276E-4
.0061
0.238E-4
DP04
6.280E-4
2.307E-4
.0012
1.537E-4
.0061
0.238E-4
TOC
.5919
.2662
1.4084
.0460
6.3765
.0012
COD
2.0466
1.1342
6.0016
.1610
30.5044
.0020
ALKIN
.1128
.0257
.1362
.0658
.5952
.0056
-------
Table 6-11
Chester River NPS Chemical Export (lbs/acre) - Z Farm (Agricultural)
Variable
Mean
Standard
Error
Standard
Deviation
Median
Maximum
Minimum
B0D5
.0746
.0326
.1131
.0337
.3984
.0017
B0D30
.1616
.0660
.2382
.0750
.8581
.0040
TSS
9.4627
4.9881
19.9526
1.1926
77.9490
.0180
N02
0.360E-4
--
—
0.360E-4
0.360E-4
0.360E-4
N03
.0019
—
—
.0019
.0019
.0019
N02N03
.0056
.0014
.0054
.0045
.0919
1.582E-4
NH3
.0038
9.240E-4
.0038
.0025
.0105
1.168E-4
TKN
.0158
.0044
.0181
.0123
.0560
2.670E-4
TKND
.0070
.0017
.0069
.0050
.0195
2.336E-4
TPHOS
.0104
.0046
.0190
.0012
.0606
0.666E-4
TPHOSD
3.246E-4
1.703E-4
7.020E-4
1.332E-4
.0030
0.100E-4
DP04
1.031E-4
0.376E-4
1.455E-4
0.633E-4
5.463E-4
0.067E-4
TOC
.2914
.1423
.5125
.0799
2.0353
6.676E-4
COD
1.0764
.4704
1.9396
.2532
7.7949
.0100
ALKIN
.0910
.0195
.0780
.0612
.2665
.0087
-------
Table 6-12
Patuxent River NPS Chemical Export (lbs/acre) - G Farm (Agricultural)
Variable
Mean
Standard
Error
Standard
Deviation
Median
Maximum
Minimum
B0D5
.3290
.2956
.5119
.0572
.9194
.0100
B0D30
.7013
.6051
1.0480
.1618
1.9187
.0503
TSS
.7029
.5524
.9568
.2763
1.7983
.0335
N02
—
—
—
—
—
—
N03
--
—
—
—
—
—
N02N03
.0433
.0403
.0698
.0050
.1239
9.869E-4
NH3
.0126
.0117
.0202
.0016
.0360
3.352E-4
TKN
.0162
.0100
.0174
.0093
.0360
.0033
TKND
.0149
.0087
.0151
.0093
.0320
.0033
TPHOS
.0321
.0331
.0512
.0038
.0919
7.039E-4
TPHOSD
.0171
.0155
.0268
.0028
.0480
4.693E-4
DP04
.0130
.0117
.0202
.0024
.0364
4.022E-4
TOC
.8778
.8003
1.3862
.0947
2.4783
.0603
COD
1.9190
1.6390
2.8389
.3257
5.1966
.2346
ALKIN
.4871
.4160
.7206
.0771
1 .3191
.0651
-------
Table 6-13
Patuxent River NPS Chemical Export (1bs/acre/in.) - All Stations
Variabl e..
Mean
Standard
Error
Standard
Deviation
Median
Maximum
Minimum
B0D5
.1412
.0349
.2586
.0648
1.4663
.0073
B0D30
.332
.0868
.7213
.1554
5.2774
.0218
TSS
13.2931
4.7827
42.2393
1 .4451
328.711
.0252
N02
4.184E-4
.796E-4
2.869E-4
3.77E-4
8.973E-4
1 .115E-4
N03
.0036
.0008
.0029
.0029
.0103
6.288E-4
N02N03
.019
.0034
.0285
.0098
.1569
1.84E-4
NH3
.006
.0018
.0162
.0015
.1289
1 .284E-4
TKN
.0425
.0126
.1149
.0098
.7773
7.93.1 E-4
TKND
.0117
.0022
.0205
.0055
.1613
.0006
TPHOS
.0471
.0185
.1683
.0032
1 .3535
1 .586E-4
TPHOSD
.0018
.0007
.0067
.0005
.0607
.801E-4
DP04
.0013
.0006
.0052
.0003
.046
.1 59E-4
TOC
.5103
.137
1 .2479
.1588
9.2301
.0083
COD
1.8365
.5078
4.6266
.4638
26.7186
.0366
ALKIN
.1863
.0569
.5085
.0858
4.2512
.0038
-------
Table 6-14
Patuxent River NPS Chemical Export (1 bs/acre/in,) - All Agricultural Sites
Variabl e
Mean
Standard
Error
Standard
Deviation
Median
Maximum
Minimum
B0D5
CO
vo
.046
.2946
.071
1 .4663
.0073
B0D30
.3974
.121
.8467
.1525
5.2774
.0291
TSS
17.4484
6.6638
49.42
2.0279
328.711
.0252
N02
2.228E-4
.392E-4
1.107E-4
1.824E-4
3.978E-4
1 .115E-4
N03
.0042
.0011
.0032
.0037
.0103
7.549E-4
N02N03
.0236
.0043
.0316
.0112
.1569
1 .84E-4
NH3
.0074
.0024
.0187
.0016
.1289
1 .284E-4
TKN
.0522
.0172
.1334
.01
.7773
7.931E-4
TKND
.0134
.003
.0236
.0057
.1613
5.964E-4
TPHOS
.0617
.0253
.1959
.0044
1 .3535
1.586E-4
TPHOSD
.0022
•
o
o
.0078
5.666E-4
.0607
.801E-4
DP04
.0015
.0008
.0061
.0003
.046
.159E-4
TOC
.6138
.1869
1 .4478
.1603
9.2301
.0083
COD
2.2307
.6934
5.3707
.4701
26.7186
.0366
ALKIN
.235
.079
.5964
.1096
4.2512
.005
-------
Table 6-15
Patuxent River NPS Chemical Export (1bs/acre/in.) - Patuxent Park (Forested)
Variable
Mean
Standard
Error
Staridard
Deviation
Median
Maximum
Minimum
B0D5
.0626
.0117
.0438
.0572
.1646
.009
B0030
.1718
.025
.1118
.1573
.4609
.0218
TSS
3.3564
2.1196
10.1654
.9435
49.3867
.1354
N02
7.314E-4
.728E-4
1.628E-4
7.257E-4
8.973E-4
5.205E-4
N03
.0026
.001
.0022
.0018
.0062
6.288E-4
N02N03
.0056
.0016
.0068
.0025
.0253
1.91E-4
NH3
.0023
6.312E-4
.003
.0014
.0153
4.513E-4
TKN
.0172
.005
.0241
.0087
.1152
9.026E-4
TKND
.0073
.0015
.007
.005
.0255
9.026E-4
TPHOS
.0091
.0049
.0237
.0027
.1152
6.318E-4
TPHOSD
9.12E-4
2.43E-4
11 .655E-4
4.236E-4
52.601E-4
.903E-4
DP04
6.08E-4
2.322E-4
10.892E-4
2.595E-4
48.579E-4
.764E-4
TOC
.2405
.0579
.2778
.1554
1.2511
.0257
COD
.8082
.198
.9496
.4337
4.2802
.0971
ALKIN
.0655
.0083
.0397
.0607
.1528
.0038
-------
Table 6-16
Patuxent River NPS Chemical Export (lbs/acre/in.) - Deale A Watershed (Agricultural)
Variable
Mean
Standard
Error
Standard
Deviation
Median
Maximum
Minimum
B0D5
.2662
.1267
.4202
.1017
1.4663
.0353
B0D30
.6269
.3443
1 .3336
.2162
5.2774
.0488
TSS
19.2393
8.2969
36.1652
6.1969
155.454
.0365
N02
1 .912E-4
.625E-4
1 .25E-4
1 .38E-4
3.774E-4
1 .115E-4
N03
.0027
.0014
.0028
.0016
.0069
7.549E-4
N02N03
.0302
.008
.0349
.0158
.1149
.0018
NH3
.0096
.0056
.027
.0013
.1289
1.284E-4
TKN
.0915
.0438
.2053
.0088
.7773
.0022
TKND
.0145
.007
.0334
.0038
.1613
7.549E-4
TPHOS
.0582
.0255
.1198
.0078
.5344
.0011
TPHOSD
.0013
.0002
.0011
.001
.0034
2.672E-4
DP04
8.482E-4
1 .242E-4
5.552E-4
7.367E-4
20.923E-4
2.019E-4
TOC
.7919
.4166
1.9538
.1877
9.2301
.0352
COD
3.2267
1 .543
7.2373
.5902
26.7186
.0716
ALKIN
.1574
.0505
.2258
.086
.8921
.005
-------
Table 6-17
Patuxent River NPS Chemical Export (lbs/acre/in.)
- Deale B Watershed (Agricultural)
Variable
Mean
Standard
Error
Standard
Deviation
Median
Maximum
Minimum
B0D5
.097
.0345
.1422
.0544
.5414
.0073
B0D30
.2304
.0845
.3873
.1213
1 .6242
.0293
TSS
23.6294
15.0525
70.6024
1 .1991
328.711
.0381
N02
2.543E-4
.508E-4
1.017E-4
2.215E-4
3.978E-4
1.763E-4
N03
.0057
.0016
.0031
.0045
.0103
.0036
N02N03
.0216
.0046
.0202
.0156
.0812
.0038
NH3
.0052
.0024
.0117
.0014
.0541
1 .491E-4
TKN
.0343
.0145
.0694
.0079
.3253
.0013
TKND
.0128
.0036
.0174
.0066
.0657
5.964E-4
TPHOS
.0945
.0612
.2935
.0026
1 .3535
4.255E-4
TPHOSD
.0011
.0003
.0013
.0006
.0051
1 .359E-4
DP04
6.514E-4
2.221E-4
10.65E-4
2.842E-4
50.928E-4
.895E-4
TOC
.5646
.258
1 .2372
.0917
5.3585
.0085
COD
1.9204
1 .0177
4.8806
.2173
22.4297
.0366
ALKIN
.2965
.1805
.8656
.0912
4.2512
.0372
-------
Table 6-18
Patuxent River NPS Chemical Export (lbs/acre/in.) -
Z Farm (Agricultural)
Variable
Mean
Standard
Error
Standard
Deviation
Median
Maximum
Minimum
B0D5
.0918
.0352
.1113
.0496
.3868
.0125
B0D3O
.2141
.0745
.2355
.1465
.8331
.0291
TSS
6.4461
2.3925
7.9351
2.129
18.5962
.1278
N02
—
—
—
—
—
, —
N03
—
—
—
--
--
—
N02N03
.0086
.0019
.0067
.0091
.0215
1.84E-4
NH3
.0049
.0012
.0043
.0051
.01 52
6.406E-4
TKN
.0204
.0047
.0162
.0152
.0421
7.931E-4
TKND
.0091
.0021
.0073
.0083
.0266
7.931E-4
TPHOS
.0096
.0042
.0145
.0023
.0466
1 .586E-4
TPHOSD
4.481E-4
2.251E-4
7.798E-4
2.561E-4
28.978E-4
.801E-4
DP04
1 .374E-4
.336E-4
1.163E-4
1.011E-4
4.108E-4
.159E-4
TOC
.2393
.0699
.2422
.1874
.8182
.0083
COD
.8896
.2481
.8594
.6829
2.901
.0625
ALKIN
.1321
.0222
.0737
.1193
.2587
.0352
-------
Table 6-19
Patuxent River NPS Chemical Export (-lbs/acre/in.) - 6 Farm (Agricultural)
Variable
Mean
Standard
Error
Standard
Deviation
Median
Maximum
Minimum
B0D5
.4638
.3553
.6154
.2201
1.1638
.0076
B0D30
1.0297
.7196
1.2464
.6225
2.4288
.0378
TSS
1.1217
.6507
1 .127
1.0628
2.277
.0252
N02
—
--
—
—
—
—
N03
—
--
—
—
—
N02N03
.0548
.051
.0884
.0038
.1569
.0038
NH3
.0173
.0142
.0246
.0061
.0455
2.52E-4
TKN
.0279
.013
.0225
.0357
.0455
.0025
TKND
.0262
.0119
.0207
.0357
.0405
.0025
TPHOS
.0438
.0365
.0633
.0144
.1164
5.293E-4
TPHOSD
.0239
.0186
.0323
.0106
.0607
3.528E-4
DP04
.0185
.014
.0243-
.0091
.046
3.024E-4
TOC
1 .1823
.9818
1.7005
.3644
3.1372
.0454
COD
2.669
1 .979
3.4278
1 .2525
6.578
.1764
ALKIN
.6594
.5082
.8803
.2505
1.6698
.058
-------
Table 6-20 Patuxent River NPS\CHemical Export (lbs/acre/yr) - All Sites
Variable Mean St. Error St. Deviafcifcn--'- ,l! Median Max. Min.
B0D5
5.9293
1.4646
10.8619
2.7204
61.5852
.3078
B0D30
13.9439
3.6469
30.2931
6.5271
221.6494
.9153
TSS
558.31
200.8716
1774.05
60.3104
13805.9
1.0585
N02
.0176
.0033
.0121
.0159
.0377
.0047
N03
.1508
.0034
.1213
.1219
.4344
.0264
N02N03
.7999
.1422
1.1986
.4097
6.5881
.0077
NH3
.2516
.074
.6786
.0639
5.4135
.0054
TKN
1.7848
.5299
4.8272
.4125
32.6453
.0333
TKND
.4922
.0942
.8631
.2303
6.7734
.025
TPHOS
1.9779
.776
7.0698
.1364
56.8477
.0067
1PH0SD
.0766
.0306
.2808
.0196
2.5502
.0034
DP04
.0538
.0246
.2196
.0126
1.9339
6.662E-4
TOC
21.4343
5.7529
52.4113
6.6683
387.6628
.3498
COD
77.1333
21.3293
194.3193
19.4813
1122.1818
1.5391
ALKIN
7.8243
2.3878
21.3567
3.6027
178.5504
.1604
-------
Table 6-21 Patuxent River NPS Chemical Export (lbs/acre/yr) - All Agricultural Sites
Variable Mean St. Error St. Deviation Median Max. Min.
B0D5
7.0559
1.9322
12.3719
2.9837
61.5852
.3078
60D3Q
16.5903
5.0804
35.5031
6.4063
221.6494
1.2242
TSS
732.835
279.879
2075.639
85.171
13805.86
1.0585
N02
.0094
.0016
.0047
.0077
.0167
.0047
N03
.1779
.0475
.1344
.1574
.4344
.0317
N02N03
.992
.1822
1.3263
.4708
6.5881
.0077
NH3
.3102
.1007
.7864
.0668
5.4135
.0054
TKN
2.1914
.7234
5.6034
.4183
32.6453
.0333
TKND
.5624
.1268
.9901
.2387
6.7734
.025
TPHOS
2.5897
1.0624
8.2294
.1838
56.8477
.0067
TPHOSD
.0911
.042
.3277
.0238
2.5502
.0034
DP04
.0645
.0336
.2563
.0134
1.9339
6.662E-4
TOC
25.779
7.85
60.809
6.734
387.663
.3498
COD
93.688
29.121
225.568
19.743
•1122.182
1.539
ALKIN
9.872
3.318
25.05
4.602
178.55
.212
-------
Table 6-22 Patuxent River NPS Chemical Export (Ibs/acre/yr) - Patuxent Park (Forested)
Variable Mean St. Error St. Deviation Median Max. Min.
B0D5
2.6301
.4914
1.8387
2.4007
6.9141
.3791
B0D30
7.2152
1.0502
4.6965
6.6069
19.3596
.9153
TSS
140.969
89.024
426.946
39.625
2074.24
5.687
N02
.0307
.0031
.0068
.0305
.0377
.0219
N03
.1075
.0417
.0933
.0743
.2623
.0264
N02N03
.2342
.067
.2842
.1058
1.0606
.008
NH3
.096
.0265
.1271
.0584
.6417
.019
TKN
.7242
.2108
1.0109
.3658
4.8399
.0379
TKND
.306
.0615
.295
. 2094
1.0695
.0379
TPHOS
.3818
.2073
.9939
.1131
4.8399
.0265
TPHOSD
.0383
.0102
.0489
.0178
.2209
.0038
DP04
.0255
.0098
.0457
.0109
.204
.0032
TOC
10.1009
2.4327
11.667
6.5271
52.5474
1.079
COD
33.9464
8.316
39.8821
18.2172
179.767
4.079
ALKIN
2.7508
.3476
1.6668
2.5504
6.4168
.1604
-------
Table 6-23 Patuxent River NPS Chemical Export (Ibs/acre/yr) - Deale A Watershed (Agricultural)
Variable Mean St. Error St. Deviation Median Max. Min.
B0D5
11.1821
5.3215
17.6495
4.2709
61.5852
1.4839
B0D30
26.3299
14.4616
56.0095
9.0792
221.6494
2.0491
TSS
808.05
348.463
1518.937
260.269
6529.057
1.5341
N02
.008
.0026
.0053
.0058
.0159
.0047
NO 3
.115
.0596
.1193
.069
.2904
.0317
N02N03
1.2688
.3358
1.4639
.6643
'4.8249
.0767
NH3
.402
.2362
1.1328
.0527
5.4135
.0054
TKN
3.842
1.8383
8.6226
.368
32.6453
.092
TKND
.61
.2924
1.4023
.1592
6.7734
.0317
TPHOS
2.4448
1.0727
5.0316
.3296
22.4436
.0481
TPHOSD
.055
.0093
.0445
.0403
.1428
.0112
DP04
.0356
.0052
.0233
.0309
.0879
.0085
TOC
33.2596
17.4955
82.0611
7.8852
387.663
1.4768
COD
135.521
64.806
303.967
24.789
1122.182
3.0088
ALKIN
6.6093
2.1204
9.4829
3.6128
37.4686
.212
-------
Table 6-24 Patuxent River NPS Chemical Export (lbs/acre/yr) - Deale B Watershed (Agricultural)
Variable Mean St. Error St. Deviation Median Max. Min.
B0D5
4.076
1,4488
5.9736
2.2833
22.7391
.3078
B0D30
9.6763
3.5497
16.2666
5.0944
68.2172
1.2313
TSS
992.434
632.204
2965.3
50.362
13805.864
1.6015
N02
.0107
.0021
.0043
.0093
.0167
.0074
N03
.2408
.0659
.1319
.1884
.4344
.152
N02N03
.9058
.1948
.8492
.6564
3.4109
.1609
NH3
.218
.1027
.4927
.0597
2.2739
.0063
TKN
1.4411
.6078
2.9151
.3324
13.6641
.0536
TKND
.5386
.152
.7288
.2788
2.7612
.025
TPHOS
3.9673
2.5702
12.3263
.1074
56.8477
.0179
TPHOSD
.0458
.0117
.0563
.0238
.2139
.0057
DP 04
.0274
.0093
.0447
.0119
.2139
.0038
TOC
23.7148
10.8352
51.964
3.85
225.056
.3575
COD
80.6589
42.742
204.983
9.1254
942.047
1.5391
ALKIN
12.4518
7.5806
36.3552
3.8306
178.55
1.5629
-------
"Table 6-25 Patuxent River NPS Chemical Export (Ibs/acre/yr) - Z Farm (Agricultural)
Variable Mean St. Error St. Deviation Median Max. Min.
B0D5
3.8553
1.4776
4.6727
2.0828
16.2457
.5247
B0D35
8.9934
3.1275
9.8901
6.155
34.9907
1.2242
TSS
270.736
100.486
333.275
89.42
781.042
5.369
N02
—
—
—
—
--
—
NO 3
—
—
—
--
—
—
N02N03
.3629
.0813
.2816
.3805
.9009
.0077
NH3
.2071
.0521
.1803
.2131
.6387
.0269
TKN
.8582
.1963
.68
.6363
1.7683
.0333
TKND
.3817
.0885
.3066
.3492
1.1177
.0333
TPHOS
.4027
.176
.6098
.0978
1.956
.0067
TPHOSD
.0188
.0095
,.0327
.0108
.1217
.0034
DP04
.0058
.0014
.0049
.0042
.0173
6.662E-4
TOC
10.0501
2.9365
10.1723
7.8711
34.3658
.3498
COD
37.3651
10.4192
36.0933
28.6813
121.843
2.6233
ALKIN
5.5466
.9337
3.0967
5.0107
10.8667
1.4798
-------
Table 6-26 Patuxent River NPS Chemical Export (Ibs/acre/yr) - G Farm (Agricultural)
Variable Mean St. Error St. Deviation Median Max. Min.
B0D5
19.481
14.9235
25.8482
9.2461
48.8794
.3176
B0D35
43.247
30.2241
52.3497
26.144
102.009
1.5878
TSS
47.1094
27.3295
47.336
44.6362
95.6336
1.0585
N02
—
—
—
—
--
--
N03
—
—
—
—
--
N02N03
2.3021
2.143
3.7118
.1594
6.5881
.1588
NH3
.7261
.5975
1.0348
.2551
1.9127
.0106
TKN
1.1723
.5465
.9465
1.4985
1.9127
.1059
TKND
1.1015
.5012
.8681
1.4985
1.7002
.1059
TPHOS
1.8386
1.5339
2.6568
.6058
4.8879
.0222
TPHOSD
1.0038
.7832
1.3565
.4464
2.5502
.0148
DP04
.7764
.5885
1.0194
.3826
1.9339
.0127
TOC
49.657
41.2342
71.4198
15.3038
131.762
1.9053
COD
112.097
83.119
143.967
52.607
276.275
7.41
ALKIN
27.6958
21.3458
36.972
10.5214
70.1313
2.4346
-------
Table 6-27
Relative Comparison Of Estimated Average Forested Watershed Chemical Export
To Estimated Average Agricultural Watershed Export (On A Pound Per Acre Per
Inch Of Rain Basis In The Patuxent River, 1980-1981, Using Data From Five
Subwatersheds)
Variable
Ratio of average Agricultural To Average
Forested Export (Ib/acre/inch of rain)
B0D5
2.7
B0D30
2.3
TSS
5.2
N02
0.3*
N03
1.6
N02N03
4.2
NH3
3.2
TKN
3.0
TKND
1.8
TPHOS
6.3
TPHOSD
2.4
DP04
2.5
TOC
2.5
COD
2.8
ALKLIN
3.6
~Suspect data due to holding time and analytical procedure
used.
188
-------
Table 6-28
Estimated Average Potential Watershed Chemical Export (Total Phosphorus)
During Storm Events to the Patuxent River Basin
Land Use Activity
Estimated
Acres In
Potential
Load
lb./yr.
Loading Rate
lb/acre/yr
Source
Agricultural
205,743
532,813
2.5897
this study
Forested
272,738
104,131
0.3818
this study
Othen^i .e. residential
commercial, industrial,
and &tfe)
58,843
37,574
1.180
•k
All Activities
537,324
674,518
--
—
*Provided by Maryland Department of State Planning
189
-------
Table 6-29
Estimated Average Potential Watershed Chemical Export During Storm
Events to the Patuxent River Basin (Total Nitrogen)**
Land Use Activity
Estimated
Acres In
Basin*
Potential
Load
Ib/yr.
Loading Rate
lb/acre/yr
Source
Cropland and Pastureland
205,743
654,962
3.1834
this study
Forested
272,738
261,392
0.9584
this study
Other (i.e. residential,
commercial, industrial,
and idle)
58,843
328,287
5.57
*
All Activities
537,324
1,244,641
~Provided by Maryland Department of State Planning.
**The total estimated loads developed from this agricultural sites are low
due to limited storm samples at watersheds in the Piedmont Province, how-
ever, the loading rate reported here has been observed at other Agricul-
tural sites in the Chesapeake Bay Region, reported by Bostater, et. al.,
1981 and Anderson and Bosca, 1981.
***This rate may be as high as 5.758 Ib/acre/yr (the upper standard deviation
of the loading rate developed from the agricultural sites monitored in this
study) or 1,184,668 Ib/yr. This value assumes that the loading rates are
independent for TKN and N02N03.
190
-------
Table 6-30 Chemical; Export Functions for the Patuxent River
NPS Watershed (lbs/acre/in. of rain) versus (gallons of storm flow)
•
Dependent
Variable
Selected Regression
Equation
N
Correlation
Coefficient (r)
Site
B0D5
InY
= (3.E-07)X - 2.9522
55
.357
All
lnY
= (3.E-07)X - 2.8626
41
.337
All Agricultural
Y =
(2.E-07JX + .02176
14
.728
Patuxent Park
lnY
= (2.E-06)X - 3.1998
11
.780
Deale A
Y =
(7.E-08)X - .02171
17
.887
Deale B
lnY
= .76257 (lnX) - 10.789
10
.528
Zepp
Y =
(6.E-06)X + .04174
3
.979
Grey
BOD30
lnY
= (3-E-07)X - 2.0859
69
.375
All
lnY
= (3.E-07)X - 2.0657
49
.369
All Agricultural
Y =
(4.E-07)X + .03899
20
.815
Patuxent Park
lnY
= (2.E-06)X - 2.6145
15
.836
Deale A
Y =
(2.E-07)X - .09601
21
.875
Deale B
lnY
= .85391 (lnX) - 10.834
10
.607
Zepp
Y =
.00001X + .18778
3
.964
Grey
TSS
Y =
.00003X - 5.731
78
.733
All
Y =
.00003X - 6.5295
55
.731
All Agricultural
-------
lO
ro
Table 6-30 Chemical Export Functions for
NPS Watershed (lbs/acre/in. of rain) versus
the Patuxent River
(qallons of storm flow)
Dependent
Variable
Selected Regression
Equation
N
Correlation
Coefficient (r)
Site
TSS (cont.)
lnY = (5.E-06)X - 1.5457
23
.748
Patuxent Park
lnY = 1.2068 (lnX) - 13.918
19
.603
Deale A
Y = .00003X - 36.79
22
.858
Deale B
Y = .00023X - 1.8529
11
.71
Zepp
Y = (1.E-05)X + .43264
3
.873
Grey
N02
lnY = .13124 (lnX) - 9-69
13
.179
All
lnY = (3.E-07)X - 8.7357
8
.640
All Agricultural
lnY = .13938 (lnX) - 8.9866
5
.352
Patuxent Park.
lnY = .00001X - 10.504
4
.755
Deale A
Y = .00014 (lnX) - .0017
4
.993
Deale B
Zepp
Grey
N03
Y = (3-E-09)X + .00214
13
.701
All
Y = (3.E-09)X + .00235
8
.801
All Agricultural
Y = -.00265 (lnX) + .03569
5
-.695
Patuxent Park
lnY = -3.8529 (lnX) + 38.967
4
-.951
Deale A
-------
Table 6-30 (cont.) Chemical Export Functions for the Patuxent River
NPS Watershed (Ibs/acre/in. of rain) versus (gallons of storm flow)
Dependent
Variable
Selected Regression
Equation
N
Correlation
Coefficient (r)
Site
N03 (cont.)
Y =
.00436 (TnX) - .05486
4
.997
Deale B
Zepp
Grey
N02N03
InY
= .48625 (lnX) - 10.845
71
.554
All
lnY
= .43011 (lnX) - 9.7827
53
.628
All Agricultural
InY
= 1.0681 (lnX) - 19.045
18
.649
Patuxent Park
Y =
(6.E-08)X - .00152
19
.844
Deale A
Y =
(9.E-09JX + .00556
19
.846
Deale B
Y =
.00365 (lnX) - .02797
12
.545
Zepp
Y =
(9.E-07)X - .00707
3
.999
Grey
NH3
InY
= (5.E-07)X - 6.6752
84
.436
All
InY
= (5.E-07)X - 6.6998
61
.444
All Agricultural
Y =
(5.E-09JX + .00076
23
.367
Patuxent Park
InY
= (3.E-06)X - 7.8874
23
.874
Deale A
Y =
(6.E-09)X - .0051
23
.915
Deale B
InY
= .93108 (lnX) - 15.088
12
.868
Zepp
-------
Table 6-30 (cont.) Chemical Export Functions for the Patuxent River
NPS Watershed (lbs/acre/in. of rain) versus (gallons of storm flow)
Dependent Selected Regression
Variable Equation
NH3 (cont.)
Y =
(2.E-07)X + .00022
TKN
-lnY
= (5.E-07)X - 4.7114
lnY
= (4.E-07JX - 4.6392
lnY
= (3.E-06)X - 5.6637
lnY
= (3.E-06)X - 5.3651
lnY
= 1.1788 (InX) - 20.867
lnY
= .93582 (InX) - 13.777
Y =
(1 .E-07)X + .01759
TKND
lnY
= (5.E-07)X - 5.4891
lnY
= (4.E-07)X - 5.4809
Y =
(2.E-08)X + .00171
lnY
= (2.E-06)X - 6.3666
lnY
= 1.0622 (InX) - 19.914
lnY
= .77042 (InX) - 12.778
Y =
(1 .E-07)X + .01795
TPHOS
Y =
(1.E-07)X - .03027
N
Correlation
Coefficient (r)
Site
3
.989
Grey
83
.392
All
60
.387
All Agricultural
23
.637
Patuxent Park
22
.770
Deale A
23
.783
Deale B
12
.748
Zepp
3
.653
Grey
84
.451
All
61
.466
All Agricultural
23
.577
Patuxent Park
23
.882
Deale A
23
.776
Deale B
12
.793
Zepp
3
.571
Grey
83
.770
All
-------
Table 6-30 (cont.) Chemical Export Functions for the Patuxent River
NPS Watershed (lbs/acre/in. of rain) versus (gallons of storm flow)
Dependent
Variable
Selected Regression
Equation
Correlation
Coefficient (r)
Site
TPHOS (cont.)
Y =
(l.E-07)X - .03383
60
.767
All Agricultural
InY
= (3.E-06)X - 6.7166
23
.635
Patuxent Park
lnY
= (3.E-06)X - 5.7125
22
.724
Deale A
Y =
(l.E-07)X - .1466
23
.856
Deale B
lnY
= .00005X - 7.6057
12
.667
Zepp
Y =
(6.E-07)X - .0001
3
.990
Grey
TPHOSD
lnY
= .31702 (lnX) - 11.294
84
.421
All
lnY
= .26654 (lnX) - 10.583
61
.395
All Agricultural
lnY
= (4.E-06)X - 8.696
23
.700
Patuxent Park
Y =
(2.E-09JX - .00046
23
.821
Deale A
lnY
= .4171 (lnX) - 13.122
23
.413
Deale B
lnY
= .65913 (lnX) - 14.935
12
.682
Zepp
Y =
(3.E-07)X + .00169
3
.982
Grey
DP04
lnY
= .34565 (lnX) - 12.222
80
.433
All
lnY
= .30715 (lnX) - 11.689
58
.410
All Agricultural
lnY
= (3.E-06)X - 9.1087
22
.697
Patuxent Park
Y =
(9.E-10JX + .00043
20
.768
Deale A
-------
Table 6-30 (cont.) Chemical Export Functions for the Patuxent River
NPS Watershed (lbs/acre/in. of rain) versus (gallons of storm flow)
Dependent
Variable
Selected Regression
Equation
N
Correlation
Coefficient (r)
Site
DP04 (cont.)
lnY
= .53622 (lnX) - 15.42
23
.511
Deale B
lnY
= .85183 (lnX) - 17.841
12
.823
Zepp
Y =
(2.E-07)X + .00187
3
.977
Grey
TOC
lnY
= (5.E-07)X - 2.1753
83
.391
All
lnY
= (5.E-07)X - 2.1702
60
.394
All Agricultural
lnY
= (4.E-06)X - 3.0583
23
.697
Patuxent Park
lnY
= (2.E-06)X - 2.4383
22
.806
Deale A
lnY
= 1.3465 (lnX) - 20.875
23
.732
Deale B
lnY
= .92772 (lnX) - 11.368
12
.688
Zepp
Y =
.00002X + .00038
3
.992
Grey
COD
lnY
= (5.E-07)X - .89732
83
.391
All
Y =
(2.E-06)X + .50577
60
.506
All Agricultural
lnY
= (3.E-06)X - 1.4778
23
.639
Patuxent Park
lnY
= (3.E-06)X - 1.5062
22
.848
Deale A
Y =
(2.E-06)X - 2.1004
23
-.859
Deale B
lnY
= .93831 (lnX) - 10.053
12
.795
Zepp
-------
Table 6-30 (cont.) Chemical Export Functions for the Patuxent River
NPS Watershed (Ibs/acre/in. of rain) versus (gallons of storm flow)
Dependent
Variable
Selected Regression
Equation
N
Correlation
Coefficient (r)
Site
COD (cont.)
Y =
.00003X + .31049
3
.982
Grey
ALKIN
lnY
= (2.E-07)X - 2.6185
80
.238
All
InY
= (2.E-07)X - 2.3907
57
.192
All Agricultural
lnY
= .36178 (lnX) - 7.4315
23
.337
Patuxent Park
Y =
(3.E-07)X + .00395
20
.657
Deale A
lnY
= (1.E-07)X - 2.3551
23
.193
Deale B
lnY
= .51506 (lnX) - 7.4363
11
.714
Zepp
Y =
(8.E-06)X + .04886
3
.990
Grey
(Lack of significance in the statistical regressions due to a small number of observations)
-------
Table 6-31 Chemical Export Functions For The Patuxent River NPS Watershed
Dependent Selected
Variable Independent Regression Correlation
lbs/acre Variable Equation N Coefficient Site
B0D5
B0D30
10
00
TSS
N02
NO 3
TRF*MINT
Y = .24308X + .00222
42
.641
All
TRF*MINT
Y = .24114X + .01327
29
.623
All Agricultural
TRF
Y = .08393X - .01347
14
.477
Patuxent Park
TRF*MINT
InY = 1.1467(1nX) - 1.1123
7
.990
Deale A
TRF*MINT
lnY = 1.0215X - 3.8631
12
.661
Deale B
TRF
InY = 2.3498(lnX) - 2.4648
10
.842
Z Farm
TRF*MINT
lnY = -1.0778X - 1.3844
3
-.749
G Farm
TRF*MINT
Y = .75861X - .11026
56
.628
All
TRF*MINT
Y=.82614X - .15482
37
.640
All Agricultural
TRF
Y = .24739X - .05038
20
.730
Patuxent Park
TRF*MINT
Y = 1.7572X - .64265
11
.956
Deale A
TRF*MINT
lnY = 1.0956X - 2.9529
16
.724
Deale B
TRF
InY = 2.3877(1nX) - 1.5513
10
.863
Z Farm
TRF*MINT
lnY = -.82172X - .52474
3
-.700
G Farm
TRF*MINT
lnY = 1.2101 (1 nX) + 1.6717
64
.673
All
TRF*MINT
lnY = 1.3715(1nX) + 1.9492
42
.677
All Agricultural
TRF*MINT
InY = :72998(TnX) + .63655
22
.651
Patuxent Park
TRF*MINT
InY = 1.5523(1nX) + 2.6080
14
.755
Deale A
TRF*MINT
InY = 2.0392(lnX) + 2.3095
17
.846
Deale B
TRF*MINT
Y = 9.2200X + .71646
8
.922
Z Farm
TRF*MINT
lnY = -1.0677X - .24511
3
-.848
G Farm
TRF
Y = .00052X - .00013
13
.642
All
TRF
Y = .00046X - .00029
8
.870
All Agricultural
TRF
Y = .00080(InX) + .00082
5
.963
Patuxent Park
TRF*AVINT
lnY = -.09669(1nX) - 8.5432
4
-.776
Deale A
TRF
Y = .00058X - .00044
4
.994
Deale B
--
--
--
--
Z Farm
--
G Farm
TRF
Y = .00786X - .00492
13
.671
All
TRF
Y = .01360X - .01106
8
.901
All Agricultural
-------
Table 6-31 (continued) Chemical Exportfunctions For The Patuxent River NPS Watershed
Dependent
Selected
Variable
Independent
Regression
Correlation
lbs/acre
Vari able
Equation
N
Coefficient
Site
N03 (cont.)
TRF
Y = .00113X + .00131
5
.348
Patuxent Park
TRF*AVINT
Y = .00178X + .00116
4
.978
Deale A
TRF
Y = .01608X - .01421
4
.997
Deale B
__
--
Z Farm
--
--
G Farm
N02N03
TRF*MINT
Y = .02184X + ,00471
57
.598
All
TRF*MINT
lnY = . 61518(;lnX)-3,9753
40
.614
All Agricultural
TRF
lnY = 1.3783(lnX) - 5.8168
18
.385
Patuxent Park
TRF*MINT
Y = .03881X + .00207
14
.981
Deale A
TRF
lnY = 1.5268(1nX) - 4.0187
19
.764
Deale B
TRF
Y = .00607(1nX) + .00891
12
.504
Z Farm
TRF
lnY = 1.5248(lnX) - 4.1078
3
.517
G Farm
NH3
TRF*MINT
Y = .01822X - .00351
70
.624
All
TRF*MINT
Y = .02002X - .00429
48
.647
All Agricultural
TRF*MINT
lnY = .32888(lnX) - 6.2421
22
.478
Patuxent Park
TRF*MINT
Y = .04060X - .01216
18
.941
Deale A
TRF
lnY = 2.2077(1nX) - 6.2210
23
.748
Deale B
TRF
lnY = 2.5119(1nX) - 5.1573
12
.853
Z Farm
TRF*MINT
lnY = 1.0650X - 4.8086
3
-.708
G Farm
TKN
TRF*MINT
Y = .10752X - .01784
69
.681
All
TRF*MINT
Y = .11749X - .02139
47
.704
All Agricultural
TRF
lnY = 1.4593(lnX) - 4.5314
23
.540
Patuxent Park
TRF*MINT
Y = .22115X - .04147
17
.947
Deale A.
TRF
lnY = 2.1806(lnX) - 4.2009
23
.753
Deale B
TRF
Y = .04928X - .01803
12
.885
Z Farm
TRF*MINT
lnY = -.58761X - 3.9515
3
-.781
G Farm
TKND
TRF*MINT
Y = .02313X - .00121
70
.636
All
TRF*MINT
lnY = .73086(lnX) - 4.4958
48
.665
All Agricultural
TRF*MINT
lnY = .37670(lnX) - 5.0597
22
.447
Patuxent Park
TRF*MINT
Y = .05082X - .01258
18
.948
Deale A
-------
Table 6-31 (continued) Chemical Export Functions For the Patuxent River NPS Watershed
Dependent
Selected
Correlation
Variable
Independent
Regression
Site
lbs/acre
Variable
Equation
N
Coefficient
TKND (cont.)
TRF
lnY
=
1.9388(lnX) - 4.9229
23
.731
Deale B
TRF
lnY
=
2.1052(1nX) - 4.6177
12
.794
Z Farm
TRF*MINT
lnY
=
-.56872X - 4.0106
3
-.797
G Farm
TPHOS
TRF*MINT
lnY
=
1.0205(1nX) - 4.0850
69
.677
All
TRF*MINT
lnY
=
1.1744(1nX) - 3.7404
47
.713
All Agricultural
TRF*MINT
lnY
=
.44016(1nX) - 5.4110
22
.520
Patuxent Park
TRF*MINT
lnY
=
1.3025(lnX) - 3.1467
17
.849
Deale A
TRF*MINT
lnY
=
1.5710(lnX) - 3.3919
18
.835
Deale B
TRF*MINT
Y =
J
010821X + .00136
9
.860
Z Farm
TRF*MINT
lnY
=
-1.1215X - 3.9010
3
-.717
G Farm
TPHOSD
TRF
lnY
=
1.5466(lnX) - 7.2047
84
.588
All
TRF
lnY
=
1.5397(lnX) - 7.1145
61
.596
All Agricultural
TRF
lnY
=
1.5496(lnX) - 7.4481
23
.571
Patuxent Park
TRF*MINT
Y =
J
00097X + .00054
18
.725
Deale A
TRF*MINT
lnY
=
.79113(1nX) - 6.5464
18
.810
Deale B
TRF
lnY
=
2.2310(lnX) - 7.8421
12
.829
Z Farm
TRF*MINT
lnY
=
-1.1026X - 4.3746
3
-.748
G Farm
DP04
TRF
lnY
=
1.5833(lnX) - 7.7703
80
.570
All
TRF
lnY
=
1.6161(lnX) - 7.6967
58
.571
All Agricultural
TRF
lnY
=
1.4579(1nX) - 7.9750
22
.574
Patuxent Park
TRF
lnY
=
1.8700X - 9.1833
20
.790
Deale A
TRF
lnY
=
1.7282(1nX) - 7.7975
23
.781
Deale B
TRF
lnY
=
3.0332X - 11.975
12
.791
Z Farm
TRF*MINT
lnY
=
-1.0829X - 4.5902
3
-.756
G Farm
TOC
TRF
lnY
=
2.3275(1nX) - 1.4739
83
.708
All
TRF*MINT
lnY
=
.96847(1nX) - .76976
47
.726
All Agricultural
TRF
. lnY
=
2.1491(lnX) - 1.6444
23
.738
Patuxent Park
TRF*MINT
lnY
=
.91662(1nX) - .61795
17
.757
Deale A
TRF*MINT
lnY
=
1.3521(lnX) - .62983
18
.848
Deale B
TRF
lnY
3.3271(1nX) - 1.1532
12
.922
Z Farm
-------
Table 6-31 (continued) Chemical Export Functions For The Patuxent River NPS Watershed
Dependent
Selected
Variable
Independent
Regression
Correlation
lbs/acre
Vari able
Equation
N
Coefficient
Site
TOC (cont.)
TRF
lnY = 3.3271(InX) - 1.1532
12
.922
Z Farm
TRF*MINT
InY = -.68747X - .69796
3
-.537
G Farm
COD
TRF*MINT
lnY = .84098(1nX) + .33409
69
.697
All
TRF*MINT
lnY = .95148(1nX) + .44426
47
.726
All Agricultural
,TRF*AVINT
lnY = .52134(lnX) + .39093
22
.627
Patuxent Park
TRF*MINT
Y = 8.0769X - 1.5326
17
.948
Deale A
TRF*MIIMT
lnY = 1.2747(1nX) + .50591
18
.846
Deale B
TRF
lnY = 2.9377(lnX) + .11547
12
.906
Z Farm
TRF*MINT
lnY = -.56333X + .28294
3
-.524
G Farm
ALKIN
TRF*MINT
Y = .11637X + .05514
66
.418
All
TRF*MINT
Y = .1201 OX + .07627
44
.412
All Agricultural
TRF
Y = .01544(1nX) + .05286
23
.252
Patuxent Park
TRF*MINT
Y = .28957X - .05090
15
.951
Deale A
TRF*MINT
lnY = .21470X - 2.4707
18
.233
Deale B
TRF
lnY = 1.2839(lnX) - 2.0894
11
.718
Z Farm
TRF*MINT
Y = -. 19669X + .69341
3
-.432
G Farm
(Lack of significance in the statistical regressions due to a small number of observations)
-------
Table 6-32 Chemical Export Functions For The Patuxent River NPS Watershed
Dependent
Selected
Variable
Independent
Regression
Correlation
lbs/acre
Variable
Equation
N
Coefficient
Site
B0D5
GAL./ACRE/IN.
InY
=.0006X - 4.1441
55
.621
All
GAL./ACRE/IN.
InY
= 1.3667(lnX) - 12.661
41
.696
All Agricultural
GAL.
Y =
(2.E-07)X - .00385
18
.884
Patuxent Park
GAL.
InY
= (3.E-06)X - 4.0740
18
.921
Deale A
GAL.
Y =
(9.E-08)X - .05884
19
.924
Deale B
GAL.
InY
= 1.2827(lnX) - 16.517
12
.811
Z Farm
GAL./ACRE/IN.
InY
= 1.5008(lnX) - 13.141
3
1.00
G Farm
B0D30
GAL.
InY
= .49981(lnX) - 8.566
89
.578
All
GAL./ACRE/IN.
InY
= .00067(1nX) - 2.9505
49
.651
All Agricultural
GAL.
Y =
(6.E-07)X - .02458
26
.896
Patuxent Park
GAL.
InY
= 1.2575(1nX) - 17.825
23
.901
Deale A
GAL.
Y =
(3.E-07)X - .16953
24
.914
Deale B
GAL.
InY
= 1.2908(lnX) - 15.676
13
.856
Z Farm
GAL./ACRE/IN.
InY
= 1.2239(1nX) - 10.051
3
.999
G Farm
TSS
GAL.
Y =
.000OTX - 8.2281
104
.776
All
GAL.
Y =
.00004X - 9.3579
74
.776
All Agricultural
GAL.
InY
= (8.E-06)X - 2.7833
30
.809
Patuxent Park
GAL./ACRE/IN.
Y =
.01366X - 7.7950
19
.751
Deale A
GAL.
Y =
.00004X - 40.472
27
.850
Deale B
GAL.
Y =
.00052X - 8.4557
16
.896
Z Farm
GAL./ACRE/IN.
Y =
.00030X - .02976
3
1.00
G Farm
N02
GAL./ACRE/IN.
InY
= .93662(lnX) - 14.108
13
.848
All
GAL.
Y =
(3.E-10)X + .00007
12
.971
All Agricultural
GAL.
Y =
(3.E-09)X - (6.E-11)
7
1.00
Patuxent Park
GAL.
Y =
(1.E-09JX - (3.E-11)
5
1.00
Deale A
GAL.
Y =
(3.E-10)X + (6.E-11)
6
1.00
Deale B
—
—
--
—
Z Farm
--
--
G Farm
N03
GAL.
Y =
8.E-09X + .00057
19
.929
All
GAL.
Y =
(8.E-09)X + .00083
12
.941
All Agricultural
-------
Table 6-32 (continued) Chemical Export Functions For The Patuxent River MPS Watershed
Dependent Selected
Variable Independent Regression Correlation
lbs/acre Variable Equation N Coefficient Site
iJ03
N02N03
ro
° NH3
TKN
GAL.
lnY
= .92799(lnX) - 17.955
7
.883
Patuxent Park
GAL./ACRE/IN.
lnY
= -.00360X - 4.5753
4
-.899
Deale A
GAL.
Y =
(9.E-09JX - .00095
6
.997
Deale B
--
—
Z Farm
—
—
G Farm
GAL.
lnY
= .62996(lnX) - 13.124
92
.633
All
GAL./ACRE/IN.
lnY
= 1.5923(1nX) - 16.003
53
.822
All Agricultural
GAL.
lnY
= 1.4249(1nX) - 23.921
23
.817
Patuxent Park
GAL.
Y =
(8.E-08)X - .01224
28
.912
Deale A
GAL.
Y =
(l.E-08)X - .00349
22
.974
Deale B
GAL./ACRE/IN.
Y =
.00001X - .00311
12
.848
Z Farm
GAL.
Y =
(7.E-07)X - .00562
3
1.00
G Farm
GAL.
lnY
= (8.E-07)X - 7.3989
111
.482
All
GAL./ACRE/IN.
lnY
= .00095X - 7.8615
61
.639
All Agricultural
GAL.
lnY
= .98464(lnX) - 18.798
30
.825
Patuxent Park
GAL.
lnY
= (4.E-06JX - 8.7631
33
.897
Deale A
GAL.
lnY
= 1.7289(lnX) - 30.74
28
.931
Deale B
GAL.
lnY
= 1.1943(1nX) - 18.115
17
.923
Z Farm
GAL./ACRE/IN.
lnY
= 1.5686(lnX) - 17.031
3
.999
G Farm
GAL.
lnY
= .60674(1nX) - 12.463
110
.541
All
GAL./ACRE/IN.
lnY
= .00083X - 5.6940
60
.576
All Agricultural
GAL.
lnY
= 1.1877(lnX) - 19.537
30
.835
Patuxent Park
GAL.
lnY
= (4.E-06JX - 6.5818
32
.817
Deale A
GAL.
lnY
= 1.7023(1nX) - 28.375
28
.869
Deale B
GAL.
lnY
= 1.2550(1nX) - 17.463
17
.856
Z Farm
GAL./ACRE/IN.
lnY
= .78285(1nX) - 10.110
3
.998
G Farm
-------
Table 6-32 Chemical Export Functions For The Patuxent River NPS Watershed
Dependent
Selected
Variable
Independent
Regression
Correlation
lbs/acre
Variable
Equation
N
Coefficient
Site
TKND
GAL./ACRE/IN.
lnY
= .00056X - 6.4037
84
.537
All
GAL./ACRE/IN.
InY
= 1.1280(1nX) - 13.204
61
.593
All Agricultural
GAL.
lnY
= .99771(1nX) - 17.792
30
.838
Patuxent Park
GAL.
InY
= 1.3032(1nX) - 21.956
33
.872
Deale A
GAL.
Y =
(1.E—08)X - .00423
28
.931
Deale B
GAL.
InY
= 1.1264(lnX) - 16.756
17
.923
Z Farm
GAL./ACRE/IN.
Y =
(5.E-06)X + .00335
3
.995
G Farm
TPHOS
GAL.
Y =
(1.E-07JX - .04152
110
.802
All
GAL.
Y =
(2.E-07)X - .04713
80
.803
All Agricultural
GAL.
lnY
- 1.1372(1nX) - 19.959
30
.816
Patuxent Park
GAL./ACRE/IN.
Y =
.00006X - .04165
22
.845
Deale A
GAL.
Y =
(2.E-07)X - .16604
28
.849
Deale B
GAL.
Y =
(5.E-07)X - .00557
17
.882
Z Farm
GAL./ACRE/IN.
lnY
= 1.6311(InX) - 16.625
3
1.00
G Farm
TPHOSD
GAL.
InY
= .57079(1nX) - 14.937
111
.611
All
GAL.
InY
= .5054(1nX) - 14.119
81
.583
All Agricultural
GAL.
lnY
= (6.E-06)X - 9.5813
30
.828
Patuxent Park
GAL.
Y =
(3.E-09)X - .00002
33
.915
Deale A
GAL.
lnY
= 1.0173(1nX) - 21.848
28
.711
Deale B
GAL.
lnY
= .99942(InX) - 18.930
17
.825
Z Farm
GAL./ACRE/IN.
InY
= 1.5384(lnX) - 16.423
3
1.00
G Farm
DP04
GAL.
InY
= .60420(lnX) - 15.900
103
.630
All
GAL.
lnY
= .53023(1nX) - 14.965
75
.589-
All Agricultural
GAL.
InY
= 1.2042(1nX) - 23.212
28
.895
Patuxent Park
GAL.
Y =
(2.E-09)X + .00004
29
.833
Deale A
GAL.
lnY
= l.OlOl(lnX) - 22.296
28
.730
Deale B
GAL.
lnY
= 1.1644(lnX) - 21.367
15
.922
Z Farm
-------
Table 6-32 (continued) Chemical Export Functions For The Patuxent River NPS Watershed
Dependent
Variable
lbs/acre
Independent
Variable
Selected
Regression
Equation
N
Correlation
Coefficient
Site
DP04 (cont.)
GAL./ACRE/IN.
InY
= 1.4950(lnX) - 16.311
3
1.00
G Farm
TOC
GAL.
Y =
(5. E—0 7)X + .11633
110
.551
All
GAL./ACRE/IN.
Y =
.00068X - .33952
60
.671
All Agricultural
GAL.
InY
= 1.1034(lnX) - 15.759
30
.798
Patuxent Park
GAL./ACRE/IN.
Y =
.0008X - .64613
22
.840
Deale A
GAL.
InY
= 1.6769(1nX) - 25.668
28
.791
Deale B
GAL.
Y =
.00001X - .14351
17
.886
Z Farm
GAL./ACRE/IN.
InY
= .00064X - 2.9719
3
1.00
G Farm
COD
GAL.
Y =
(3.E-06)X - .01555
110
.610
All
GAL./ACRE/IN.
Y =
.00315 - 1.9690
60
.630
All Agricultural
GAL.
InY
= 1.1301(lnX) - 14.952
30
.842
Patuxent Park
GAL.
InY
= 1.4937(lnX) - 19.479
32
.875
Deale A
GAL.
Y =
(3.E-06)X - 2.4707
28
.861
Deale B
GAL.
Y =
.00005X - .59603
17
.900
Z Farm
GAL./ACRE/IN.
InY
= .00054X - 1.6115
3
1.00
G Farm
ALKIN
GAL.
InY
= .33765(lnX) - 7.0283
104
.507
All
GAL./ACRE/IN.
Y =
.00013X - .04032
57
.678
All Agricultural
GAL.
InY
= .6558(1nX) - 11.254
29
.748
Patuxent Park
GAL.
InY
= ..90869(lnX) - 14.152
28
.825
Deale A
GAL.
InY
= (4.E-07)X - 3.1325
28
.649
Deale B
GAL.
InY
= .83640(lnX) - 11.115
16
.950
Z Farm
GAL.
InY
= .00002X - 2.8504
3
1.00
G Farm
(Lack of significance in the statistical regressions due to a small number of observations)
-------
Table 6-33
Patuxent River Chemical Export Functions Developed From Hultlple Linear Regression
Dependent
Variable Multiple Linear Multiple
(lbs/acre) Regression Equation* r2 N Station
.111(X31+1.039(X5)-.666E-1
.122(X3)+1.046(X5)-.87E-1
.837
42
All
.836
29
All Agricultural
.154E-1(X4)+.202E-1
.906
13
Patuxent Park
-,625(X2)+.57(X3)-.593E-2(X4)+.824(X5)-.333E-1
.998
7
Deale A
-.37(X1)-.52(X2)+.771(X3)+l.483(X5)+.222E-1
.991
12
Deale 8
.289(XI)-.412(X3)+.33E-l(X4)-l .125(X5) + .155E-1
.977
7
Z Fa nm
-,625(X2)+.57(X3)-.593E-2(X4)+.824(X5)-.333E-1
.998
7
G Farm
.117E-1(X2)+.106E-3(X4)+.106(X5)-.126E-2
.920
52
All
.123E-1(X2) + .102E-3(X4) + . 105(X5)-.585E-3
• 920
35
All Agricultural
.137E-2(X4)+.215E-2
.353
17
Patuxent Park
.266E-1(XI)-.407E-1(X2J+.61E-1 (X3)-.263E-3(X4)-.188E-l
.975
11
Deale A
-.502E-1(XI)-.605E-1(X2)+.902E-1(X3)+.485E-4(X4)+.176(X5)+.138E-1
.992
13
Deale 8
•461E-1(X5)+.197E-2
.444
8
Z Farm
.266E-1(XI)-.407E-1(X2) + .61E-1 (X3)-.263E-3{X4J-.188E—1
.975
11
G Farm
,944E-2(X3)+.537E-4(X4)+.731E-l(X5)-.73E-2
.724
64
All
. 109E-1 (X3)+.547E-4(X4)+.734E-1(X 5)-.965E-2
.728
42
All Agricultural
.393E-1(X5)-.203E-3
.301
22
Patuxent Park
.502E-2(X1)-.481E-3(X4)+.152(X5)-.503E-2
.994
14
Deale A
-.296E-2(X1)+.537E-2(X3)+.934E-4(X4)+.633E-l(X5)-.347E-2
.986
17
Deale B
-,49E-2(X3)+.281E-3(X4)+.631E-1(X5)-.981E-3
.919
8
Z Farm
.502E-2(X1)—.481E-3(X4)+.152(X5)-.503E-2
.994
14
G Farm
,151E-1(X2)+.394E-2(X4)+.102(X5)-.164E-1
.954
64
All
.173E-1(X2)+.395E-2(X4)+.108(X5)-.23E-1
.954
42
All Agricultural
-.211E-2(XI)+.351E-2(X2)+.32E-2(X4)+.l16E-2
.967
22
Patuxent Park
-.123E-1(X2)+.974E-1(X3)+.136E-2(X4)-.289E-1
.957
14
Deale A
-.81E-1(X1)+.103(X3)+.305E-2(X4)-.96(X5)-.453E-1
.976
17
Deale B
*Independent Var
Xl=total ra
ables:
nfall X2*average Intensities X3»max1mum Intensity X4*total suspended solids X5>alkal1n1ty
-------
Table 6-33 (continued)
Patuxent River Chemical Export Functions Developed From Multiple linear Regression
Dependent
Variable
Multiple Linear
Multiple
(lbs/acre)
Regression Equation*
N '
Station
TPHOS (cont.)
V-
.903E-2(X1)+.155E-1(X2)+.367E-1(X3)-.207E-2(X4)+.253E-1(X5)-.114E-1
.994
8
Z Farm
Y=
-.123E-1(X2)+.974E-1(X3)+.136E-2(X4)-.289E-1
.957
14
G Farm
TPHOSD
Y=
.113E-2(X2)-•368E-2(X3)-.136E-4(X4)+.238E-1(X5)+.817E-3
.631
64
All
Ya
.U6E-2(X2)-.398E-2(X3)-.133E-4(X4)+.241E-l(X5)+.997E-3
.638
42
All Agricultural
Y=
.147E-2(X2)-.978E-3(X3)+.661E-3(X4)+.l53E-3
.834
22
Patuxent Park
Y=
.135E-2(XI)-.576E-3(X2)+.119E-2(X3)-.515E-3
.664
14
Deale A
Y=
.206E-2(X3)+.145E-3
.411
17
Deale B
Y a
.528E-3(XI)+.325E-3(X2)-,919E-4(X3)+.678E-3(X5)-.251E-3
.948
8
Z Farm
Ya
.135E-2{XI)-,576E-3(X2)+.119E-2(X3)-.515E-3
.664
14
G Farm
DP04
Ya
. 107E-2(xl)+.74E-3(X2)-.354E-2(X3)-.981E-5(X4)+.183E-1(X5)-.263E-4
.644
61
All
Y=
-.333E-2(X3)+.177E-1(X5)+.108E-2
.63
40
All Agricultural
Y=
.128E-2(X2)+.264E-3(X4)+.llE-l(X5)-.483E-3
.589
21
Patuxent Park
.105E-2(X1)-,233E-3(X2)+.12E-2(X5)-.2E-3
.649
12
Deale A
.411E-5(X4)+.69E-3
.088
17
Deale 6
Ya
.56E-3(XI)+.268E-3(X2)+.188E-3(X3)-.243E-4(X4)-.283E-3
.937
8
Z Farm
Ya
,105E-2(Xl)-.233E-3(X2)+.12E-2(X5)-.2E-3
.649
12
G Farm
TOC
Ya
-.258(XI)+.268(X2)+.861(X3)+.787E-2(X4)+1.382(X51-.557E-1
.706
64
All
Y=
-,465(X1)+.292(X2)+.974(X3)+.797E-2(X4)+1.354(X5)-.889E-2
.716
42
All Agricultural
.279(XI)-.157(X3)+.506E-1(X4)+l.2(X5)-.107
.747
22
Patuxent Park
Y=
-,225(X2)+1,616(X3)+.299E-1(X4)-l.167(XS)-.5 74
.956
14
Deale A
Y=
-,74(Xl)-.435(X2)+3.214(X3)-.275E-2(X4)+7.293(X5)-.732
.972
17
Deale B
.635(XI )+.386(X2)-. 7<;7(X3) + .598E-1 (X4J-.253
.964
8
Z Farm
Ya
-.225(X2)+1,616(X3)+.299E-1(X4)-l.167(X5)-.574
.956
14
G Farm
COD
2.849(X3)+.508E-1(X4J+11,652(X5)-1.485
.852
64
All
Y=
3.218(X3)+.509E-1(X4)+l1.646(X5)-2.013
.857
42
All Agricultural
Y»
.478(XI)+l,754(X2)-.967(X3)+.199(X4)+4.155(X5)-.188
.803
22
Patuxent Park
-.582(X2)+4.67(X3)+17.404(X5)-1.678
.981
14
Deale A
Y°
-.629(Xl)-.367(X2)+2.683(X3)+.542E-l(X4)+10.(X5)-.803
.998
17
Deale B
Y-
1.823(XI)-2.024(X3)+.2(X4)-3.683(X5)-.223
.981
8
Z Farm
Yb
-.582(X2)+4.67(X3)+17.404(X5)-1.678
.981
14
G Farm
-------
Table 6-34
Patuxent River Chemical Export Functions Developed From Multiple Linear Regression
Dependent
Variable
(lbs/acre)
Multiple Linear
Regression Equation
Multiple
R2
N
Station
B0D5
Y-
5.682(X7)+.907E-1(X1)-.165(X2)+1.102(X5)+4.851(X9)-.604E-1
.925
42
All
V*
6.74{X7)+.108(X1)-.178(X2)+.966(X5>-.884E-1
.925
29
All Agricultural
Y»
-,312E-1(X2)+4.856(X4)+.222E-1
.90)
30
Patuxent Park
..
--
--
Oeale A
—
..
Deale B
..
—
—
Z Farm
..
—
—
G Farm
N02N03
Y»
-.102E-l(X2)+.439E-l(X4)+.113(X5)+.199E-l(X6)+2.542(X9)+.526E-2
.967
42
All
Y-
--631E-2(X3)+2.196(X8)-.106E-1(XI)-.176E-1(X2)~.494E-1(X4)+.163(X5)+.282E-2
.975
29
All Agricultural
Y-
-1.849(X8)+.179(X6)-.993E-3
.648
30
Patuxent Park
--
Deale A
..
—
Deale B
..
—
—
Z Farm
—
G Farm
NH3
Y-
.169(X7)-1.232(X8)-.19E-l(XS)+.837E-l(Xi)-.273E-2
.968
42
All
Y»
. 189(X7)-3.391 (X8)+. 756E-1 {X6)+2.996C X'J J-32E-2
.97
29
All Agricultural
Y ¦
¦ ,234(X8)+.668E-3(X1)~.153E-2(X2)~.334E-3
.631
30
Patuxent Park
—
--
—
Deale A
--
..
Deale B
—
—
Z Farm
—
—
G Farm
TPHOS
Y-
15.088{X7)-33.409(X8)+.347(X2)-2.281(X5)-.941E-1
.845
42
All
*
Y»
15.02(X7)-96.1(X8)+.466(X2)-2.258(X5)+33.38(X9)-.129
.886
29
All Agricultural
Y-
2.429(X8)+.556E-1(X6)+l.334(X9)-.113E-2
.966
30
Patuxent Park
—
—
—
Oeale A
--
--
Deale B
•Independent Variables:
Xl»total rainfall X2»average Intensity X3=rcaxi:nu/n intensity XWPHOS X5-TKN X6-TKN X6=B0D5 X7-N02N03
-------
Table 6-34 (continued)
Patuxent River Chemical Export Functions Developed From Multiple Linear Regression
Dependent
Variable
(lbs/acre)
Multiple Linear
Regression Equation
Multiple
R2
N
Station
TPHOS (cont.)
„
' Z Farm
--
—
--
G Farm
TPHOSD
Y»
•16E-2(X2)-.82E-3(X4)+1.312(X9)-.328E-4
.984
42
All
V»
.183E-2(X2)-.103(X4)*1.321(X9)-.673E-4
.997
29
All Agricultural
Y=
.105E-2(X2)+.274(X4)-.456(X9)-.37E-4
.939
30
Patuxent Park
—
--
Deale A
—
—
—
Deale B
—
—
—
Z Farm
—
--
—
G Farm
DP04
Y=,
. 139E-1 (X7)+.72(X8)-.869E-3(X2)-.267E-2(X5)-.354E-4
.985
42
All
Y=
.755-.I39E-2(X2)+.783E-3(X4)+.572E-4
.997
29
All Agricultural
Y=
-.947(X8)+.207E-2(X2)+.333(X4)-.111E-3
.786
30
Patuxent Park
—
—
—
Deale A
—
—
—
Deale B
—
—
Z Farm
--
G Farm
TOC
Y=
87.36(X8)+.342(X1)+1.121(X2)+2.089(X4)+7.416(X5)-2.497(X6)-.242
.943
42
All
Y»
.345(X1)-l.434(X2)+1,85(X4)+6.873(X5)-2.303(X6)+111.29{X9)-.235
.952
29
All Agricultural
Y°
124.3(X8)+.893E-1(XI)-.209(X2)-17.16(X4)+2.72(X5)+1.995(X6)-.556E-1
.974
30
Patuxent Park
--
--
--
Deale A
—
—
—
Deale B
—
—
—
Z Farm
—
G Farm
COO
Y=
51.45(X7)-.493.3(X8)+.716(X1M0.29(X4)+12.9(X5)+5.333(X6)+445.7(X9)-.6Z4
.978
42
All
Y»
68.74(X7)-1897.7(X8)+1.043(X1)+2.099(X2) 8.559(X4)+13.79(X5)+3.983(X6)+2280.7(X9)-1.139
.988
29
All Agricultural
Y=
154.7(X8)+1.50(X2)+88.2(X4)-11.03(X5)-175.1(X9)+.158E-1
.994
30
Patuxent Park
~Independent Variables:
Xl=total rainfall X2=average intensities X3«maximum Intensity X4-TPK0S X5»TKH X6°S005 X7«N02N03
-------
Table 6-34 (continued)
Patuxent River Chemical Export Functions Developed From Multiple Linear Regression
Dependent
Variable
(lbs/acre)
Multiple Linear
Regression Equation
Multiple
R*
N
Station
COD (cont.)
_ _
Deale A
-•
--
—
Oeale B
—
Z Farm
--
--
—
G Farm
TKN
Y= 3.472(X7)+.415E-l(X3)-.586E-l(Xl)+.878E-l(X2)-.215(X4)+.165(X6)-13.s5(X9)+.162E-2
.959
42
All
Y= 3.867(X7)+.509E-l(X3)-.83E-l(Xl)t.883E-l(X2)-.219(X4)«-.138(X6)-13.96(X9)+.516E-2
.972
29
All Agricultural
Y= 1.242(X4)+.436E-2
.536
30
Patuxent Park
—
--
--
Deale A
—
—
«
Deale B
—
--
--
Z Farm
"
G Farm
Independent Variables:
XI"total rainfall X2=average Intensity X3=maximum intensity X4-TPH0S X5-TKN X6-B0D5 X7-N02N03 X8»TPH0SD X9-0P04
-------
Table6-35Bulk Precipitation Quality At Patuxent River Park
NPS Station From September 1980 Through November 1980
Storm Date
Volume
(cm)
PH
T0C
(mg/1)
N0o + N02
(mg/1)
TKN
(mg/1)
T. Phosphorous
(mg/1)
9/25/80
2.46
6.4
12.
0.35
3.1
0.40
10/18/80
4.80
4.9
16.
0.20
3.3
0.26
10/25/80
5.18
4.9
<2.
0.20
0.5
0.01
11/4/80
0.76
6.6
—
--
1.1
0.37
11/18/80
3.28
--
2.
0.95
0.7
0.04
11/25/80
-1.73
5 5
10.
o
CM
0.3
0.03
11/27/80
1.02
5.3
4.
0.70
0.1
0.01
(-) - no data
(<) - less than
-------
Table6-36Buik Precipitation Quality At Patuxent River Park
NPS Station From December 1980 Through February 1981
Storm Date
Volume
(cm)
T0C
(mg/1)
NO3 + NO?
(mg/1)
TKN
(mg/1)
T. Phosphorous
(mg/1)
2/2/81
2.06
3.
1.4
0.5
0.03
2/8/81
0.99
4.
1.0
0.2
0.03
2/11/81
1.96
<2.
0.45
<0.1
0.02
2/19-20/81
0.97
10.
1.0
0.2
0.06
2/21-23/81
2.87
<2.
0.60
0.3
0.01
(<) - less than
-------
Table 6-37 Buik Precipitation Quality At Patuxent River Park
NPS Station From March 1981 Through June 1981
Storm Date
Volume
(cm)
PH
TOC
(mg/1)
NOq + NOo
(mg/1)
TKN
(mg/1)
T. Phosphorous
(mg/1)
3/5/81
1.22
5.3
4.
0.95
0.1
0.05
3/30/81
0.76
5.1
4.
2.9
1 .5
0.28
4/1/81
1.62
4.7
<2.
0.65
2.4
0.37
4/5/81
1.82
N/A
<2.
0.90
0.6
0.06
4/9/81
0.44
N/A
6.
1 .4
ISV
0.07
4/12-12/81
1.41
4.7
2.
0.75
0.8
ISV
4/23/81
1.49
4.6
10.
1.00
2.3
0.10
4/30-5/1/81
2.41
4.6
15.
1.35
6.8
0.49
5/11/81
2.51*
5.9
10.
0.85
3.8
0.27
5/15/81
1.92
5.9
6.
0.55
2.4
0.05
5/20/81
1.72
5.3
2.
0.50
1.1
0.05
5/28/81
3.23*
5.0
7.
0.55
3.6
0.59
6/2/81
1 .90*
5.7
-
-
-
0.88
6/10/81
1.35
5.4
8.
1.1
3.0
0.27
6/13/81
2.72
5.0
2.
0.62
0.8
0.01
6/19/81
1.37*
3.5
4.
1 .1
1.8
0.12
* Raingauge malfunction at Patuxent Park no data available.
Rainfall volume listed is average of volume recorded at Deale A and B stations.
N/A = Not Available
( < ) = less than
(- ) = no data
-------
Table 6-38 Bulk Precipitation Quality At Patuxent River Park
NPS Station From July 1981 Through August 1981
Storm
Volume
TOC
NOo + N09
TKN
Total
Date
(CM)
PH
(mg/1)
(mg/1) 2
(mg/1)
Phosphorous
(mg/1)
7-2-81
2.56
4.9
3.
0.30
0.45
0.03
7-4-81
3.20*
5.5
4.
0.10
1.8
0.28
7-13-81
1.19*
4.9
4.
0.95
3.6
0.26.
7-25-81
1.32*
6.0
6.
1.6
1.2
0.17
7-28-81
1.40
4.3
6.
1 .3
2.0
0.20
* Raingage malfunction at Patuxent River; no data available.
Rainfall volume listed is average of volume recorded at Deale A & B stations
-------
APPENDIX F
LONGITUDINAL SLACK SURVEY FIGURES AND TABLES
SECTION 7
215
-------
19-
18
17-
16
15
14'
13
12
11
10
9
8
7
6
5
4
3
2
1
1000 SLACK 8URVEYS
10
®
IL
o
X
0>
0>
0>
CO
o
IO
CO
*
CI
in
o>
-111
in
111
a
o
o
X
X
X
II
10
'it
li
20
D-O
20 June
21 July
20 July
20 August
10 September
10 October
13 November
4 December
O O1900 Average
¦o «
10 a
* *
X x
a. a
CO
o
-------
INS
-J
1981 SLACK SURVEYS
— 19 March
•—• 21 April
o—o 27 April
14 May
*-4 11 June
a—& 29 June
~—a 16 July
30 July
~—a 13 August
to
30 35
NAUTICAL MILES
Figure 7-2 Patuxent River Main Channel Station Salinity (ppt) Slack Tide Profiles for 1981.
-------
MARCH 19.1981
0-00
16-00 32-00
NAUTICAL MILE
48-00
O-a
-------
JULY 21.1980
0-00 16-00 32-00
NAUTICAL MILE
48. 00
0.00 16-00 32-00
NAUTICAL MILE
48.00
PATUXENT RIVER
AUGUST 20,1980
0-00
16.00 32-00
NAUTICAL MILE
48-00
0.00
16.00 32.00
NAUTICAL MILE
48-00
Figure7-3 Patuxent River longitudinal slack survey plots of salinity
(ppt).
219.
-------
OCTOBER 16.I 980
"0 • 00 16.00 32.00
NAUTICAL MILE
48-00
0.00
16-00 32.00
NAUTICAL MILE
48-00
PATUXENT RIVER
NAUTICAL MILE NAUTICAL MILE
Figure 7-3 Patuxent River longitudinal slack survey plots of salinity
(ppt).
22Q
-------
NAUTICAL MILE NAUTICAL MILE
PATUXENT RIVER
NAUTICAL MILE NAUTICAL MILE
Figure 7-3 Patuxent River longitudinal slack survey plots of salinity
(ppt).
221
-------
NAUTICAL MILE
PATUXENT RIVER
Figure 7-3 Patuxent River longitudinal slack survey plots of salinity
(PPt).
222
-------
JUNE 25.1980
3K-B0TT01
H-AVERAGE
A-SURFACE
0.00 16.00 32.00
NAUTICAL MILE
48. 00
LUO
q;°
3o.
I—CM
<
en
LU
Q-O
510
^OJ
o
o
JULY 21.1980
*-B0TT0M
H-AVERAGE
A-SURFACE
0.00 16.00 32-00
NAUTICAL MILE
48.00
PATUXENT RIVER
NAUTICAL MILE NAUTICAL MILE
Figure 7-4 Patuxerit River Slack Survey Plots of Temperature
223
-------
NAUTICAL MILE NAUTICAL MILE
PATUXENT RIVER
NOVEMBER 13.1980
K-BOTTOM
X-AVERAGE
A-SURFACE
"b'.oo 16-00 32-00
NAUTICAL MILE
48.00
o.
ro
LUO
or°
=>64
t—OI
<
en
LU
0_O
5TO
o.
DECEMBER 4.1980
^-BOTTOM
X-AVERAGE
A-SURFACE
'0.00 16-00 32-00
NAUTICAL MILE
48.00
Figure 7-4 Patuxent River Slack Survey Plots of Temperature
224
-------
MARCH 19.i 981
3K -B0T T01
H-AVERAGE
A-SURFACE
o
o
o.
r>
UJo
CC°
1—CM
-------
o
o
JUNE 11.1981
o
o
JUNE 29,1981
o_i
ro
^-BOTTOM
H-AVERAGE
A-SURFACE
Q-O
5ZO
LlJ
o_
X - BOT TO^l
K-AVERAGE
A-SURFACE
0.00 16-00 32-00
NAUTICAL MILE
48-00
o
o
0.00 16.00 J2-00
NAUTICAL MILE
46 .00
PATUXENT RIVER
NAUTICAL MILE NAUTICAL MILE
Figure 7-4 Patuxent River Slack Survey Plots of Temperature
226
-------
, AUGUST 13, 1981
o -
o
o
°0.00 i 6.00 32.00 48-00
NAUTICAL MILE
PATUXENT RIVER
Figure 7-4 Patuxent River Slack Survey Plots of Temperature
227
-------
JULY 21.i 980
0.00
;6.00 32•00
NAUTICAL MILE
48-00
0-00
16-00 32.00
NAUTICAL MILE
48-00
PATUXENT RIVER
NAUTICAL MILE NAUTICAL MILE
Figure 7-5 Patuxent river longitudinal plots of pH.
228
-------
OCTOBER I6.19K0
"0.00 16-00 52. ¦ 00
NAUTICAL MILE
48 00
0. 00
16-00 32-00
NAUTICAL MILE
48- 00
PATUXENT RIVER
NAUTICAL MILE NAUTICAL MILE
Figure 7-5 Patuxent river longitudinal plots of pH.
2291
-------
^RIl 21 . i 981
MARCH 19.i981
UD,
jk-botto^i
K-AVERAGF.
a-SURFACE
'0'. 00 16-00 32-00
NAUTICAL MILE
48.00
X
CL
O
or
"1
ID,
X -BOTTOM
W-AVERAGE
a-SURFACE
'0-00 16-00 32.00
NAUTICAL MILE
48.00
PATUXENT RIVER
NAUTICAL MILE
1 MAY 14.1981
o
°°1
H-AVERAGE
0 | ^-SURFACE
°_j ((
"b.OO 16-00 32.00 48.00
NAUTICAL MILE
Figure 7-5 Patuxent river longitudinal plots of pH.
23GL
-------
JUNE 1
i 98 i
o ;
o I
»
ro1
•JUNE 29. i 98 i
o
o
*-B0TT0M
H-AVERAGE
^-SURFACE
0.00 16-00 32•00
NAUTICAL MILE
48-00
PATUXENT RIVER
¦«r
W1
JULY 16.1981
JULY 30.1981
o
o
ID,
*-B0TT0M
H-AVERAGE
a-SURFACE
3K-B0TT0M
H-AVERAGE
A-SURFACE
o I
o ;
'0-00 1 6 - 00 52 - 00
NAUTICAL MILE
48-00
0 . 00 1 6 - 00 '32 • 00
NAUTICAL MILE
48 • 00
Figure 7-5 Patuxent river longitudinal plots of pH.
231
-------
AUGUST )5.i98i
o
*0 "
«1
a-SURFACF
o
°i
"b.OO 16-00 32 • 00 48-00
NAUTICAL MILE
PATUXENT RIVER
Figure 7-5 Patuxent river longitudinal plots of pH.
232
-------
PATUXENT RIVER
Figure 7-6 Patuxent River longitudinal slack survey plots of secchi
disc (meters).
233
-------
NAUTICAL MILE NAUTICAL MILE
P-ATUXENT RIVER
NAUTICAL MILE NAUTICAL MILE
Figure 7-6 Patuxent River longitudinal slack survey plots of secchi
disc (meters).
234
-------
PATUXENT RIVER
Figure 7-6 Patuxent River longitudinal slack survey plots of secchi
disc (meters).
235
-------
I H JUNE 11 . i <38.
o
— °i_i * JUNE 29. . 981
C/)°1
cm
LU
' JULY 16.i 981
o
a
ca
LlJ
J—
UJ
£S;
°1
o
CO
NAUTICAL MILE
PATUXENT RIVER
' JULY 30.i 981
o ,
-------
NAUTICAL MILE NAUTIGAL MILE
PATUXENT RIVER
NAUTICAL MILE NAUTICAL MILE
Figure 7-7 Patuxent River Slack Survey Plots of Dissolved Oxygen
237
-------
NAUTICAL MILE NAUTICAL MILE
PATUXENT RIVER
NAUTICAL MILE NAUTICAL MILE
Figure 7-7 Patuxent River Slack Survey Plots of Dissolved Oxygen
238
-------
MARCH 19.1981
X-BOTTOM
H-AVERAGE
^-SURFACE
0.00 16-00 32•00
NAUTICAL MILE
48.00
o
sO
O
r.
o
ZO
o
>-
X
o
~ o
UJ
o
CO
CO
APRIL 21.1981
S-BOTTOM
H-AVERAGE
^-SURFACE
0-00 16-00 32-00
NAUTICAL MILE
48-00
PATUXENT RIVER
NAUTICAL MILE NAUTICAL MILE
Figure 7-7 Patuxent River Slack Survey Plots of Dissolved Oxygen
239
-------
NAUTICAL MILE NAUTICAL MILE
PATUXENT RIVER
NAUTICAL MILE NAUTICAL¦MILE
Figure 7-7 Patuxent River Slack Survey Plots of Dissolved Oxygen
240
-------
NAUTICAL MILE
PATUXENT RIVER
Figure 7-7 Patuxent River Slack Survey Plots of Dissolved Oxygen
241
-------
0-00 16-00 32.00 48.00
NAUTICAL MILE
0-00 16-00 32-00
NAUTICAL MILE
48.00
PATUXENT RIVER
NAUTICAL MILE NAUTICAL MILE
Figure 7-8 Patuxent River longitudinal slack survey plots of Dissolved
Oxygen Saturation (%).
242
-------
NAUTICAL MILE • NAUTICAL MILE
PATUXENT RIVER
NAUTICAL MILE NAUTICAL MILE
Figure 7-8 Patuxent River longitudinal slack survey plots of Dissolved
Oxygen Saturation (%).
243
-------
MARCH 19.1981
^-BOTTOM
H-AVERAGE
A-SURFACE
0.00 16-00 32-00
NAUTICAL MILE
48.00
o
o
, 00
CO
LO.
APRIL 21.1981
JK-B0T T 01
W-AVERAGE
A-SURFACE
0-00 16.00 32.00
NAUTICAL MILE
48.00
PATUXENT RIVER
Figure 7-8 Patuxent River longitudinal slack survey plots of Dissolved
Oxygen Saturation (%).
244
-------
0.00
JUNE 29.1981
'6-00 32.00
NAUTICAL MILE
48.00
0.00
i 6.00 32.00
NAUTICAL MILE
48- 00
PATUXENT RIVER
NAUTICAL MILE NAUTICAL MILE
Figure 7-8 Patuxent River longitudinal slack survey plots of Dissolved
Oxygen Saturation (%).
245
-------
PATUXENT RIVER
Figure 7-8 Patuxent River longitudinal slack survey plots of Dissolved
Oxygen Saturation (%).
246
-------
NAUTICAL MILE NAUTICAL MILE
PATUXENT RIVER
NAUTICAL MILE NAUTICAL MILE
Figure 7-9 Longitudinal plots of dissolved nitrate, 1980-1981.
247
-------
NAUTICAL MILE NAUTICAL MILE
PATUXENT RIVER
NAUTICAL MILE NAUTICAL MILE
Figure 7-9 Longitudinal plots of dissolved nitrate, 1980-1931.
248
-------
MARCH 19.i9R1
0-00
16-00 32.00
NAUTICAL MILE
48-00
0.00
16-00 32-00
NAUTICAL MILE
48-00
PATUXENT RIVER
APRIL 27.i981
0-00
16-00 32 • 00
NAUTICAL MILE
48-00
0.00
16-00 32.00
NAUTICAL MILE
48-00
Figure 7-9 Longitudinal plots of dissolved nitrate, 1980-1981.
249-
-------
NAUTICAL MILE NAUTICAL MILE
PATUXENT RIVER
NAUTICAL MILE NAUTICAL MILE
Figure 7-9 Longitudinal plots of dissolved nitrate, 1980-1981.
25Q
-------
PATUXENT RIVER
Figure 7-9 Longitudinal plots of dissolved nitrate, 1980-1981
251
-------
IUNE 25.I9R0
16-00 32.00
NAUTICAL MILE
48-00
co
¦o
Ijo
N.
o
LUo
Qi
CO
CO
Qo
o
IULY 21.i9R0
0-00 16.00 32.00
NAUTICAL MILE
48.00
PATUXENT RIVER
0-00
AUGUST 20,i980
16-00 32.00
NAUTICAL MILE
48.00
16-00 32.00
NAUTICAL MILE
48-00
Figure 7-10Patuxent river longitudinal plots of dissolved nitrite.
252
-------
NAUTICAL MILE NAUTICAL MILE
PATUXENT RIVER
DECEMBER 4.1980
•00 16-00 32.00
NAUTICAL MILE
48-00
0-00
16-00 32.00
NAUTICAL MILE'
48-00
Figure 7-10 Patuxent river longitudinal plots of dissolved nitrite.
253
-------
X
CD
71
LUO
CH
~Z".
CO
CO
Qo
O
SEPTEMBER 15.I9R0
¦- BOTTOM
-- AVERAGE
¦ - SURFACE
0.00 16.00 32-00
NAUTICAL MILE
48.00
0. 00
i 6.00 32.00 48.00
NAUTICAL MILE
PATUXENT RIVER
.APRIL 21.1981
16-00 32-00
NAUTICAL MILE
48-00
O
"O
UJo'
ce
CO
CO
Qo
o
APRIL 27.1981
BOTTOM
0-00
16.00 32-00
NAUTICAL MILE
48-00
Figure 7-10Patuxent river longitudinal plots of dissolved nitrite.
254
-------
00
-o"
o
r.
JUNE 11.i 981
*-BOTTOM
H-AVERAGE
A-SURFACF
oo
V
- (D~
51
JUNE 29.198i
3K-90TT0M
K-AVERAGE
^-SURFACE
J.00 15.00 32-00
NAUTICAL MILE
48.00
0.00
i 6•00 32-00
NAUTICAL MILE
48. 00
PATUXENT RIVER
0.00
JULY JO.i 981
16-00 32-00
NAUTICAL MILE
48-00
0.00
16-00 32-00
NAUTICa MILE
48-00
Figure 7-10 Patuxent river longitudinal plots of dissolved nitrite.
255
-------
PATUXENT river
Figure 7-10Patuxent river longitudinal plots of dissolved nitrite.
256
-------
NAUTICAL MILE NAUTICAL MILE
PATUXENT RIVER
vj JULY 28. i 980
BOTTOM
AVERAGE
SURFACE
""0.00 16-00 32-00 48.00
NAUTICAL MILE
o
< -
CO
CO
Oo
o
AUGUST 20.1980
BOTTOM
0-00 16.00 32.00
NAUTICAL MILE
48-00
Figure 7-11 Patuxent River Slack Survey Plots of Dissolved Ammonia
257
-------
NAUTICAL MILE NAUTICAL NILE
PATUXENT RIVER
NAUTICAL MILE NAUTICAL MILE
Figure7-11 Patuxent River Slack Survey Plots of Dissolved Ammonia
258
-------
NAUTICAL MILE NAUTICAL MILE
PATUXENT RIVER
0.00
16-00 32-00
NAUTICAL MILE
48-00
0.00
16-00 32.
NAUTICAL M
48-00
Figure 7-11 Patuxent River Slack Survey Plots of Dissolved Ammonia
259
-------
NAUTICAL MILE NAUTICAL MILE
PATUXENT RIVER
NAUTICAL MILE NAUTICAL MILE
Figure 7-11 Patuxent River Slack Survey Plots of Dissolved Ammonia
260
-------
NAUTICAL MILE
Figure 7-11 Patuxent River Slack Survey Plots of Dissolved Ammonia
261
-------
NAUTICAL MILE NAUTICAL MILE
PATUXENT RIVER
NAUTICAL MILE NAUTICAL MILE
Figure 7-12 Patuxent River longitudinal slack survey plots of Total
Particulate Nitrogen (mg/1).
262
-------
NAUTICAL MILE NAUTICAL MILE
PATUXENT RIVER
NAUTICAL MILE NAUTICAL MILE
Figure 7-12 Patuxent River longitudinal slack survey plots of Total
Particulate Nitrogen (mg/1).
.263
-------
PATUXENT RIVER
Figure 7-12 Patuxent River longitudinal slack survey plots of Total
Particulate Nitrogen (mg/1).
254
-------
NAUTICAL MILE NAUTICAL MILE
PATUXENT RIVER
JULY 16.1981
o
-------
PATUXENT RIVER
Figure 7-12 Patuxent River longitudinal slack survey plots of Total
Particulate Nitrogen (mg/1).
266
-------
NAUTICAL MILE NAUTICAL MILE
PATUXENT RIVER
NAUTICAL MILE NAUTICAL MILE
Figure 7-13Patuxent river longitudinal plots of dissolved total kjeldhal
nitrogen.
267
-------
NAUTICAL MILE NAUTICAL MILE
PATUXENT RIVER
NAUTICAL MILE NAUTICAL MILE
F1gure7-13 Patuxent river longitudinal plots of dissolved total kjeldhal
nitrogen.
268
-------
NAUTICAL MILE NAUTICAL MILE
PATUXENT RIVER
NAUTICAL MILE NAUTICAL MILE
Figure 7-13 Patuxent river longitudinal plots of dissolved total kjeldhal
nitrogen.
263
-------
NAUTICAL MILE NAUTICAL MILE
PA'TUXENT RIVER
NAUTICAL MILE NAUTICAL MILE
Figure 7-13 Patuxent river longitudinal plots of dissolved total kjeldhal
nitrogen.
270
-------
PATUXENT RIVER
Figure 7-13Patuxent river longitudinal plots of dissolved total kjeldhal
nitrogen.
271
-------
o
JUNE 25.i980
*-B0rT0M
K-AVERAGE
A-SURFACE
16-00 02--00 48-00
NAUTICAL MILE
0-00
16•00 32. 00
NAUTICA MILE
48-00
PATUXENT RIVER
JULY 28.i980
0-00
AUGUST 20.1980
16-00
NAUTICAL
16-00 32.00
NAUTICAL MILE
48.00
Fiqure 7-14Patuxent river longitudinal plots of dissolved organic nitrogen.
272
-------
OCTOBER 16.1980
16-00 32-00
NAUTICAL MILE
16-00 32-00
NAUTICAL MILE
48-00
FaTUXENT river
NAUTICAL MILE NAUTICAL MILE
Figure7-14Patuxent river longitudinal plots of dissolved organic nitrogen.
2.73
-------
MARCH 19.198!
0.00
APRIL 21 . 1 98 i
X--B0T tom
K - AVERACF
a-SURFACE
16.00 32.00
NAUTICAL MILE
48.00
0-00
1 6 • 00 32-00
NAUTICAL MILE
48-00
PATUXENT RIVER
O I
.<*>
APRIL 27.1981
-BOTTOM
H-AVERAGE
^-SURFACE
0.00
16.00 32.00
NAUTICAL MILE
48-00
0-00
1 6 • 00 32.00
NAUTICAL MILE
48.00
Figure7-14Patuxent river longitudinal plots of dissolved organic nitrogen,
274
-------
NAUTICAL MILE NAUTICAL MILE
PATUXENT RIVER
NAUTICAL MILE NAUTICAL MILE
Figure 7-14Patuxent river longitudinal plots of dissolved organic nitrogen.
2.75
-------
NAUTICAL MILE
PATUXENT RIVER
Figure 7-14 Patuxent river longitudinal plots of dissolved organic nitrogen.
276
-------
NAUTICAL MILE NAUTICAL MILE
PATUXENT RIVER
NAUTICAL MILE NAUTICAL MILE
Figure 7-15 Patuxent river longitudinal plots of total organic carbon.
277
-------
PATUXENT RIVER
Figure 7-15Patuxent rfver longitudinal plots of total organic carbon.
278
-------
JULY 21 . 1 980
0-00
16.00 32.00
NAUTICAL MILE
48.00
0.00
16.00 32-00
NAUTICAL MILE
48-00
PATUXENT RIVER
NAUTICAL MILE NAUTICAL MILE
Figure 7-16 Patuxent River Slack Survey Plots of Total Phosphorus
279
-------
SEPTEMBER I 5.19R0
OCTOBER 16.IOKO
* ¦ BOT T 0^1
H-AVERAGE
A-SURFACF
'0.00 16-00 32-00 48-00
NAUTICAL MILE
'0-00 i 6 - 00 32-00
NAUTICAL MILE
48- 00
PATUXENT RIVER
NAUTICAL MILE NAUTICAL MILE
Figure 7-16Patuxent River Slack Survey Plots of Total Phosphorus
280
-------
MARCH 19.i981
48.00
o
"5
O
-in
• OP
CO
~
CL tj
O
IT)
o
o.
I-
^PRIL 21. i9R1
* - b oT T: j m
W-AVERAGE
A-SURFACF
NAUTICAL MILE
¦00 16.00 32.00
NAUTICAL MILE
48-00
PATUXENT RIVER
NAUTICAL MILE NAUTICAL MILE
Figure 7-16Patuxent River Slack Survey Plots of Total Phosphorus
281
-------
PATUXENT RIVER
NAUTICAL MILE NAUTICAL MILE
Figure 7-16Patuxent River Slack Survey Plots of Total Phosphorus
282
-------
NAUTICAL MILE
PATUXENT RIVER
Figure7-16 Patuxent River Slack Survey Plots of Total Phosphorus
283
-------
JUNE 25.1980
o
10
JULY 21.1980
K-B0TT0M
H-AVERAGE
^-SURFACE
0.00-
16.00 32.00
NAUTICAL MILE
48-00
Oo
0_O
^-BOTTOM
H-AVERAGE
A-SURFACE
0-00
i
16.00
NAUTICAL
48-00
PATUXENT RIVER
Figure 7-17Patuxent river longitudinal plots of total particulate phosphorus.
284
-------
oo
.SEPTEMBER 15. i 980
^-BOTTOM
W-AVERAGE
A-SURFACE
0.00
16-00 32.00
NAUTICAL MILE
48- 00
cao
r:
OCTOBER 16.1980
3K-B0TT0M
W-AVERAGE
A-SURFACE
0-00
16.OC 32.00
NAUTICAL MILE
48-00
PATUXENT RIVER
coo
r
NO/EMBER 13,1980
0.00
JK-BOTTOM
W-AVERAGE
A-SURFACE
16.00 32.00 48-00
NAUTICAL MILE
CDO
DECEMBER 4.1980
^-BOTTOM
W-AVERAGE
A-SURFACE
"0-00 16.00 32.00
NAUTICAL MILE
48.00
Figure 7-17Patuxerit river longitudinal plots of total particulate phosphorus,
285
-------
NAUTICAL MILE NAUTICAL MILE
PATUXENT RIVER
NAUTICAL MILE NAUTICAL MILE
Figure7-17 Patuxent river longitudinal plots of total particulate phosphorus.
286
-------
PATUXENT RIVER
NAUTICAL MILE NAUTICAL MILE
Figure 7-17Patuxent river longitudinal plots of total particulate phosphorus.
287
-------
AUGUST 13.i981
o
CO
NAUTICAL MILE
PATUXENT RIVER
Figure 7-17Patuxent river longitudinal plots of total particulate phosphorus.
288
-------
JUNE 25. i 980
0-00 16.00 <52.00
NAUTICAL MILE
48-00
o
zz
'—10
N-
o"
CO
o
X
Q_io
*o
• o"
CO
CO
Oio
o
JULY 2).1980
0.
*-B0TT0M
W-AVERAGE
A-SURFACE
-m—m *
00 16.00 32-00
NAUTICAL MILE
48-00
PATUXENT RIVER
NAUTICAL MILE NAUTICAL MILE
Figure 7-18Patuxent River Slack Survey Plots of Dissolved Phosphorus
289
-------
NAUTICAL MILE NAUTICAL MILE
PATUXENT RIVER
NAUTICAL MILE NAUTICAL MILE
Figure7-18Patuxent River Slack Survey Plots of Dissolved Phosphorus
290
-------
MARCH 19.i 98 i
5K-30TT0M
H-AVERAGE
A-SURFACF
¦ «-
'0-00 16.00 32-00
NAUTICAL MILE
48-00
o
71
CO
o
X
a ^
ro
CO
CO
APRIL 21 .i 981
X-BQTT0M
W-AVERAGE
A-SURFACF
'0-00 16-00 32.00
NAUTICAL NILE
48-00
PATUXENT RIVER
APRIL 27.1980
*-B0TT0M
H-AVERAGE
A- SURFACE
-m—*-
'0-00 16-00 32 • 00
NAUTICAL MILE
48- 00
O
cn
o
Q_lO
n
CO
CO
h—t
o
o,
MAY 14.i 98 I
*-B0TT0M
W-AVERAGE
^-SURFACE
.00 16-00 32.00
NAUTICAL MILE
48 • 00
Figure 7-18Patuxent River Slack Survey Plots of Dissolved Phosphorus
291
-------
NAUTICAL MILE NAUTICAL MIlE
PATUXENT RIVER
NAUTICAL MILE NAUTICAL MILE
Figure 7-18Patuxent River Slack Survey Plots of Dissolved Phosphorus
292
-------
NAUTICAL MILE
PATUXENT RIVER-
Figure 7-18 Patuxent River Slack Survey Plots of Dissolved Phosphorus
293
-------
JUNE 25.1980
0.00
16.00 32.00
NAUTICAL MILE
48-00
-J8
v ..
o-'
T
. o
00
CO .
Oo
H
0_
o
no
I— ^
Qio'
o
JULY 21.1980
-- BOTTOM
-- AVERAGE
¦ - SURFACE
0-00
16-00 32•00
NAUTICAL MILE
48-00
PATUXENT RIVER
AUGUST 20.i980
o. 00
20.00 40-00
NAUTICAL MILE
60-00
0-00
i 6•00 32.00
NAUTICAL MILE
48-00
Figure 7-19 Patuxent River Slack Survey Plots of Dissolved Ortho-Phosphorus
294
-------
NAUTICAL MILE NAUTICAL MILE
PATUXENT RIVER
NAUTICAL MILE NAUTICAL MILE
Figure 7-19 Patuxent River Slack Survey Plots of Dissolved Ortho-Phosphorus
295
-------
NAUTICAL MILE NAUTICAL MILE
PATUXENT RIVER
NAUTICAL MILE NAUTICAL MILE
Figure 7-19 Patuxent River Slack Survey Plots of Dissolved Ortho-Phosphorus
296
-------
PATUXENT RIVER
JULY i 6. I 981
o
CM
._l
\-
o
51 K-BOTTOM
H-AVERAGE
o
A-SURFACE
JULY 30. i 981
o
_1 •_
o
21 *-B0TT0"i
tt-AVERAGE
o
A-SURFACE
Oo
X
CL.
O
XO
NAUTICAL MILE
Figure 7-19 Patuxent River Slack Survey Plots of Dissolved Ortho-Phosphorus
297
-------
PATUXENT RIVER
Figure 7-19 Patuxent River Slack Survey Plots of Dissolved Ortho-Phosphorus
298
-------
PATUXENT RIVER
Figure 7-20 Patuxent river longitudinal plots of total nitrogen to total
phosphorus ratio.
239L
-------
PATUXENT RIVER
Figure 7-20Patuxent river longitudinal plots of total nitrogen to total
phosphorus ratio.
30a
-------
MARCH 19.i9R1
0.00
¦ 00 >32 ¦ 00
NAUTICAL MIlE
48-00
o
o
-
-------
NAUTICAL MILE NAUTICAL MILE
PATUXENT RIVER
NAUTICAL MILE NAUTICAL MILE
Figure 7-21 Patuxent River Slack Survey Plots of Dissolved N:P Ratio
302
-------
SEPTEMBER 15.1980
*-SOT TOM
X-AVERAGE
A-SURFACE
0.00
16.00 32.00
NAUTICAL MILE
48.00
OCTOBER 16.1980
0-00
16-00 32-00
NAUTICAL MILE
48-00
PATUXENT RIVER
DECEMBER 4.1980
0.00
16.00 32.00
NAUTICAL MILE
48.00
16.00
NAUTICAL
46.00
Figure 7-ZI Patuxent River Slack Survey Plots of Dissolved N:P Ratio
303
-------
MARCH 19.1981
* RQrUlM
H-AVERAGE
A-SURF ACE
0.00
16.00 32.00
NAUTICAL MILE
48-00
Oo.
_C7>
«c
an
o
o
a o.
to
Qo
LlJO
-*0.
__Jk>
O
in
C/D
QO
o
APRIL 21.1981
*-sottom
H-AVERAGE
A-SURFACE
0-00 16.00 32-00
NAUTICAL MILE
48.00
PATUXENT RIVER
NAUTICAL MILE NAUTICAL MILE
Figure 7-21 Patuxent River Slack Survey Plots of Dissolved N:P Ratio
304
-------
JULY 21.i980
0.00
16.00 32-00
NAUTICAL MILE
48.00
0.00
16.00 32.00
N A U T I C A'L MILE
48-00
PATUXENT RIVER
AUGUST 20.1980
0-00
16-00 32-00
NAUTICAL MILE
48.00
0.00
16.00 32-00
NAUTICAL MILE
48-00
Figure 7-22Patuxent River longitudinal slack survey plots of BOD5.
305
-------
0-00
16-00 32-00
NAUTICAL MILE
48.00
0-00
16-00 32.00
NAUTICAL MILE
48-00
PATUXENT RIVER
DECEMBER 4.1980
0-00
16-00 32.00
NAUTICAL MILE
48-00
0.00
16.00 32.00
NAUTICAL MILE
48.00
Figure7-22 Patuxent River longitudinal slack survey plots of BOD5.
306
-------
—Jo
X to
OJH
r
~ to
O
CD™
MARCH 19.1981
3K-90TT0M
W-AVERAGE
A-SURF^CF
0-00 16.00 32.00
NAUTICAL MILE
48-00
Qro
O
CD
c\j
APRIL 21.1981
*-ROT TOM
W-AVERAGF
A-SURFACF
13.00 16-00 32.00 48-00
NAUTICAL MILE
PATUXENT RIVER
MAY 14.1981
0.00
16.00 32.00
NAUTICAL MILE
48-00
0.00
16.00 32.00
NAUTICAL MILE
48-00
Figure 7-22Patuxent River longitudinal slack survey plots of BOD5.
307
-------
o
JUNE 11 ,i 98 i
* --B0T TOI
H-AVERAGE
A SURFACF
0-00 i 6 ¦ 00 32-00
NAUTICAL MILE
48 - 00
JUNE 29.i 98 i
5K -30T T01
X-AVERA6E
A -SURFACF
0-00
16.00 32-00
NAUTICAL MILE
48-00
PATUXENT RIVER
NAUTICAL MILE NAUTICAL MILE
Figure 7-22 Patuxent River longitudinal slack survey plots of BOD5.
308
-------
PATUXENT RIVER
Figure7-22 Patuxent River longitudinal slack survey plots of BOD^.
309.
-------
JUNE 25.1980
*-B0TT0M
H-AVERAGE
A-SURFACE
~b'. 00 16-00 32-00
NAUTICAL MILE
48.00
o
o
\o.
Oro
n
o
QO
s-
•JULY 2) . 1 980
^-BOTTOM
H-AVERAGE
^-SURFACE
0-00 16-00 32-00
NAUTICAL MILE
48.00
PATUXENT RIVER
JULY 28.1980
*-B0TT0M
X-AVERAGE
A-SURFACE
"0.00 16-00 32-00 48.00
NAUTICAL MILE
O
O
*}¦
\o.
Oro
o
QO
S!2-
AUGUST 20.1980
3K-B0TT0M
K-AVERAGE
^-SURFACE
0-00 16-00 32-00
NAUTICAL MILE
48 • 00
"Figure 7-23Patuxent river longitudinal plots of chemical oxygen demand.
31Q
-------
SEPTEMBER 15.1980
JK -B0T T 01
H-AVERAGE
A- SURF ACE
"0.00 16-00 32-00
NAUTICAL MILE
48-00
o
o
^o.
On
o
QO
S?-
OCTOBER 16.1980
*-B0TT0M
W-AVERAGE
A-SURFACE
"O'-OO 16.00 32-00
.NAUTICAL MILE
48 • 00
PATUXENT RIVER
NOVEMBER 13,1980
*-B0TT0M
W-AVERAGE
A-SURFACE
"0. 00 16-00 32 • 00 48. 00
NAUTICAL MILE
^o.
o
QO
S?
DECEMBER 4.1980
K-B0TT0M
W-AVERAGE
A-SURFACE
tl.00 16.00 32.00
NAUTICAL MILE
48.00
Figure 7-t23 Patuxent river longitudinal plots of chemical oxygen demand.
311
-------
o
o
\
o
-o
o
CM
MARCH 19.198 i
JK-BQTTOM
H-AVERAGE
A-SURFACE
0-00
16-00 32-00
NAUTICAL MILE
48 • 00
o
o
APRIL 21.1981
V
O
ZD
~s
-o
xo
oH
cr
o
oo
o
X-30H0M
H-AVERAGE
^-SURFACE
0-00 16.00 32.00
NAUTICAL MILE
48 • 00
PATUXENT RIVER
o
o
APRIL 21.1981
X-B0TT0M
M-AVERAGE
A-SURFACE
00 16.00 32•00
•NAUTICAL MILE
48.00
0-00
16-00 32-00
NAUTICAL MILE
48-00
Figure 7-24 Patuxent river longitudinal slack survey plots of chlorophyll-a.
312
-------
o
o
JUNF. 11.i98i
0. 00
16-00 32-00
NAUTICAL MILE
48.00
o I
o
jiol
o
CM.
>-o
XO
JUNE 29.i 98i
tKCALEi. 2'.J>
*-B0TT01
W-AVERAGE
O-^i a-SURFACE
0(M |
0C i
o
Oo !
o ;
0.00 16.00 32-00
NAUTICAL MILE
48 • 00
PATUXENT RIVER
NAUTICAL MILE NAUTICAL MILE
Figure 7-24 Patuxent river longitudinal slack survey plots of chlorophyll-a.
313
-------
o ! AUGUST 20. 1981
o ;
PA T UXEN T RIVER
Figure 7-24 Pstuxent rtver longitudinal slack survey plots of chlorophyll-a,
314
-------
O '
o
JUNE 25.i980
o JULY 21.i980
o :
—i
\
o
Z3
0-00
^-BOTTOM
H-AVERAGF
O
Z>
*-B0TT0M
16.00
NAUTICAL
16.00 32-00
NAUTICAL MIlE
48.00
PATUXENT RIVER
o i JULY 28. i 980
O
=r1
:
o
NAUTICAL MILE
o I AUGUST 20.1980
o I
1
NAUTICAL MILE
Fioure 7-25 Longitudinal plots of pheophytin-a, 1980-1981.
315
-------
o
o
SEPTEMBER 15.1980
O
'O I
o I
:?1
3K-B0TT0M
H-AVERAGE
A- SURFACE
0.00
16-00
NAUTICAL
48.00
o
o
OCTOBER 16.i980
\.
o
r>
*-B0TT0M
H-AVERAGE
A-SURFACE
0-00
1 6-00
NAUTICAL
PATUXENT RIVER
o
o
o
ZD
NOVEMBER IJ.1980
*-B0TT0M
K-AVERAGE
A-SURFACE
o
o
:~1
o
DECEMBER 4.1980
'o 1
° I
:21
^-BOTTOM
H-AVERAGE
^-SURFACE
0.00
16-00
NAUTICAL
48. 00
0-00
16.00 62.00
NAUTICAL MILE
Figure 7-25 Longitudinal plots of pheophytin-a, 1980-1981
315
-------
NAUTICAL MILE NAUTICAL MILE
PATUXENT RIVER
0-00
16.00
NAUTICAL
16-00 32.00
NAUTICAL MILE
48-00
Figure 7-25 Longitudinal plots of pheophytin-a, 1980-1981.
317
-------
JUNE 29. 1 981
0-00
16-00
NAUTICAL
i 6 • 00 32-00
NAUTICAL MILE
48.00
PATUXENT RIVER
30.i981
16.00 32 • 00
NAUTICAL MILE
6-00 32.00
NAUTICAL MILE
48.00
Figure 7-25 Longitudinal plots of pheophytin-a, 1980-1981.
318
-------
0-00
16-00 32-00
NAUTICAL MILE
48.00
PATUXENT RIVER
Figure 7-25 Longitudinal plots of pheophytin-a, 1980-7981.
319
-------
JULY 21.)980
0-00
16-00 '32.00
NAUTICAL MILE
48-00
0.00
16.00 32-00
NAUTICAL MILE
48.00
PATUXENT RIVER
NAUTICAL MILE NAUTICAL MILE
Figure7-26 Patuxent River Slack Survey Plots of Dissolved Silica
320
-------
NAUTICAL MILE NAUTICAL MILE
PATUXENT RIVER
NAUTICAL MILE
Figure 7-26 Patuxent River Slack Survey Plots of Dissolved Silica
321
-------
o
o
1-1
o
5=
SEPTEMBER 15.i980
* -BOr TOM
H-AVERAGE
^-SURFACE
0.00 16-00 32.00
NAUTICAL MILE
48-00
o
o
3*1
\
o
5= i
o
o
o
a
MARCH 19. 1 981
* -BOTTOM
W-AVERAGE
0-00
16-00 32-00
NAUTICAL MILE
48-00
PATUXENT RIVER
o • «iPRIl 27, 1 981
O !
0.00
16-00 32.00
NAUTICAL MILE
48-00
0.00
16.00 32.00
NAUTICAL MILE
48-00
Figure 7-26Patuxent River Slack Survey Plots of Dissolved Silica
322
-------
o
o
3-1
O
z:
MAY 14.i981
* -BOT TOM
K-AVERAGE
a-SURFACE
0-00
16-00 32-00
NAUTICAL-MILE
48-00
o
o
o
T.
o
o
c
o
JUNE 11.i98 i
* -bdt rnri
K-AVERAGE
a-SURFACE
16-00 32-00
NAUTICAL MILE
48-00
PATUXENT RIVER
NAUTICAL MILE NAUTICAL MILE
Figure 7-26Patuxent River Slack Survey Plots of Dissolved Silica
323
-------
0-00
AUGUST 13, 1981
16-00 32.00
NAUTICAL MILE
48-00
16-00 32-00
NAUTICAL MILE
48-00
PATUXENT RIVER
Figure 7-26 Patuxent River Slack Survey Plots of Dissolved Silica
324
-------
JULY 21 .I 980
o°,
0.00
16-00 Z2¦00
NAUTICAL MILE
48-00
0°0
16-00 32.00
NAUTICAL MILE
48-00
PATUXENT RIVER
o°r
AUGUST 20,.980
0.00
16-00 '62 • 00
NAUTICAL MILE
48-00
0°r
0.00
16-00 32.00
NAUTICAL MILE
48.00
Figure7-27 Patuxent River Slack Survey Plots at Total Nonfilterable
residue
325
-------
PATUXENT RIVER
Figure 7-27Patuxent River Slack Survey Plots of Total Nonfilterable
residue
326
-------
o
PATUXENT RIVER
Figure7-27 Patuxent River Slack Survey Plots of Total Nonfilterable
residue
327
-------
PATUXENT RIVER
Figure 7-27Patuxent River Slack Survey Plots of Total Nonfilterable
residue
328
-------
PATUXENT RIVER
Figure 7-27 Patuxent River Slack SUrvey Plots of Total Nonfilterable
residue
329
-------
Table 7-1 Statistical Summary of Patuxent River Slack
Survey Data for 1980-1981
Standard
Standard Mean Coefficient of
Variable Year N Mean Deviation Error Variation
TEMP
80
148
20.43
8.50
0.70
41.58
81
164
20.04
7.30
0.57
36.40
DO
80
143
7.50
2.61
0.22
34.74
81
160
7.09
2.45
0.19
34.57
DOSAT
80
145
82.85
21.09
1.75
25.46
81
160
79.00
19.68
1 .56
24.91
B0D5
80
153
2.70
1.75
0.14
65.00
81
172
2.96
1.37
0.10
46.14
PH
80
148
7.43
0.46
0.04
6.20
81
162
7.38
0.43
0.03
5.78
TALK
80
111
56.36
13.66
1.30
24.23
81
172
54.87
13.81
1.05
25.16
SAL IN
80
108
10.31
5.71
0.55
55.40
81
115
11.68
5.89
0.55
50.45
RESIDUE
80
115
32.24
25.29
2.36
78.43
81
178
44.83
57.19
4.29
127.58
TOTN
80
165
1.32
1.63
0.13
123.59
81
174
1.24
1.09
0.08
88.12
DISSNIT
80
149
0.88
0.97
0.08
111.34.
81
174
1.03
1.09
0.08
105.52
FAMMON
80
164
0.16
0.34
0.03
205.59
81
174
0.20'
0.31
0.02
155.81
FNITRITE
80
164
0.03
0.07
0.01
188.70
81
175
0.04
0.06
0.0
162.55
FNITRATE
80
164
0.57
0.98
0.08
172.90
81
175
0.78
0.56
0.12
198.51
TPHOS
80
169
0.19
0.26
0.02
131.94
81
178
0.19
0.21
0.02
111.21
FPHOS
80
164
0.10
0.18
0.01
185.94
81
174
0.09
0.12
0.01
144.72
FOPHOS
80
165
0.09
0.20
0.02
210.23
81
174
0.06
0.12
0.01
190.51
TOC
80
113
7.55
3.73
0.35
49.38
81
2
4.50
2.83
2.0
62.85
DOC
80
54
11.11
4.58
0.62
41.26
81
174
4.17
1.96
0.15
46.96
CHLORIDE
80
63
3414.7
3102.7
390.8
90.85
81
0
—
—
—
—
SILICA
80
111
5.29
3.03
0.29
57.17
81
174
4.29
3.47
0.26
80.91
CHLORA
80
163
19.95
41.02
3.21
205.61
81
172
23.71
19.00
1.45
80.14
CHLORAC
80
0
—
—
—
—
81
152
16.32
14.80
1.20
90.67
PHEOP
80
164
4.84
4.77
0.37
98.47
81
172
7.39
11.92
0.91
161.23
330
-------
Table 7-2
Statistical Summary of Patuxent River Slack Survey
Data for 1980-1981. Surface, 8ottom, and Mid Depths
Variable
Depth
Year
N
Mean
Standard
Deviation
Standard
Mean
Error
Coefficient
of Variation
TEMP
S*
80
56
21.14
8.69
1.16
41.09
S
81
63
20.76
7.48
0.94
36.04
M*
80
28
18.51
8.09
1.53
43.69
M
81
31
18.43
6.60
1.19
35.82
6*
80
64
20.65
8.51
1.06
41.19
B
81
70
20.12
7.41
0.89
36.82
DO
S
80
56
7.95
2.32
0.31
29.13
S
81
63
7.54
2.18
0.27
28.86
M
80
23
7.19
2.44
0.51
33.97
M
81
27
6.54
1.55
O.30
23.65
B
80
64
7.22
2.87
0.36
39.77
B
81
70
6.91
2.89
0.35
41.88
DOSAT
S
80
56
90.64
18.16
2.43
20.04
S
81
63
86.01
15.36
1.94
17.86
M
80
25
72.57
14.66
2.93
20.21
M
81
27
69.61
12.85
2.47
18.46
B
80
64
80.06
23.30
2.91
29.11
B
81
70
76.32
23.05
2.75
30.20
B0D5
S
80
63
3.32
1.87
0.24
56.48
S
81
71
3.18
1.28
0.15
40.373
M
80
21
3.35
1.53
0.33
45.67
M
81
27
3.71
1.51
0.29
40.66
B
80
69
1.93
1 .37
0.17
71.21
B
81
74
2.49
1 .23
0.14
49.36
PH
S
80
56
7.60
0.40
0.05
5.29
S
81
63
7.57
0.42
0.05
5.54
M
80
28
7.10
0.44
0.08
6.23
H
81
31
6.98
0.30
0.05
4.31
B
80
64
7.42
0.44
0.06
5.94
B
81
68
7.40
0.35
0.04
4.78
TALK
S
80
46
59.17
12.69
1.87
21.45
S
81
69
56.77
12.87
1.55
22.67
M
80
15
38.85
4.98
1.29
12.82
M
81
27
39.84
7.99
1.54
20.05
B
80
50
59.03
12.46
1.76
21.10-
B
81
76
58.48
12.82
1.47
21.92
SAL IN
S
80
54
10.02
5.69
0.77
56.74
S
81
58
11.23
5.90
0.77
52.53
M
80
0
—
—
—
—
M
81
0
—
—
—
--
B
80
54
10.60
5.77
0.79
54.50
B
81
57
12.14
5.90
0.78
48.63
* Surface, M1d, and Bottom
331
-------
Table 7-2 (continued)
Statistical Summary of Patuxent River Slack Survey
Data for 1980-1981', Surface, Bottom, and Mid Depths
Variable
Depth
Year
N
Mean
Standard
Deviation
Standard
Mean
Error
Coefficient
of Variatic
RESIDUE
S
80
45
26.96
12.12
1.81
44.97
S
81
71
34.27
17.91
2.12
52.26
M
80
20
22.8
11.48
2.57
50.36
M
81
31
29.29
16.34
2.93
55.77
B
80
50
40.78
34.18
4.83
83.81
B
81
76
61.04
82.71
9.49
135.52
TOTN
S
80
66
0.91
0.67
0.08
73.57
S
81
71
0.86
0.54
0.06
62.68
M
80
24
3.49
0.91
0.19
26.19
M
81
27
3.36
0.79
0.15
23.45
B
80
75
0.98
1.85
0.21
189.18
B
81
76
0.83
0.56
0.06
67.39
DISSNIT
S
80
65
0.62
0.49
0.06
78.46
S
81
71
0.70
0.68
0.08
97.30
M
80
15
3.37
0.85
0.22
25.36
M
81
27
3.13
0.80
0.15
25.73
B
80
69
0.57
0.41
0.05
71.87
B
81
76
0.60
0.47
0.05
77.83
FAMMON
S
80
66
0.06
0.09
0.01
142.33
S
81
71
0.12
0.20
0.02
175.75
M
80
24
0.63
0.63
0.13
101.00
M
81
27
0.59
0.48
0.09
81.03
B
80
74
0.10
0.19
0.02
187.34
B
81
76
0.13
0.19
0.02
138.61
FINITRITES
S
80
66
0.01
0.02
0.0
120.64
S
81
71
0.01
0.02
0.0
122.81
M
80
24
0.14
0.12
0.02
89.00
M
81
27
0.15
0.08
0.02
51.79
B
80
74
0.02
0.02
0.0
129.64
B
81
77
0.02
0.02
0.0
141.08
FNITRATE
S
80
66
0.21.
0.39
0.05
185.41
S
81
71
0.47
0.94
0.11
199.73
M
80
24
2.64
0.82
0.17
31.18
M
81
27
2.24
0.49
0.09
22.02
B
80
74
0.21
0.38
0.04
177.85
B
81
77
0.56
1.94
0.22
343.87
TPHOS
S
80
66
0.10
0.10
0.01
100.41
S
81
71
0.11
0.07
0.01
63.49
M
80
29
0.65
0.30
0.06
45.79
M
81
31
0.54
0.25
0.04
46.12
B
80
74
0.10
0.09
0.01
91.06
B
81
76
0.13
0.13
0.02
103.07
332
-------
Table 7-2 (continued)
Statistical Summary of Patuxent River Slack Survey
Data for 1980-1981, Surface, Bottom, and Mid Depths
Variable
Depth
Year
N
Mean
Standard
Deviation
Standard
Mean
Error
Coefficient
of Variation
FPHOS
S
80
66
0.05
0.03
0.0
69.74
S
81
71
0.06
0.10
0.01
173.22
M
80
24
0.41
0.32
0.07
78.26
M
81
27
0.28
0.18
0.03
63.47
B
80
74
0.04
0.02
0.0
52.69
B
81
76
0.05
0.02
0.0
34.32
FOPHOS
S
80
66
0.03
0.02
0.0
79.98
S
81
71
0.02
0.02
0.0
100.19
M
80
26
0.44
0.32
0.06
73.83
M
81
27
0.27
0.18
0.03
64.82
B
80
73
0.03
0.02
0.0
86.17
B
81
76
0.02
0.02
0.0
94.70
TOL
S
80
44
7.99
4.43
0.67
55.46
S
81
0
—
—
—
—
M
80
20
8.78
4.21
0.94
47.92
M
81
2
4.50
2.83
2.00
62.85
B
80
49
6.65
2.49
0.36
37.43
B
81
0
—
—
—
—
DOC
S
80
20
10.53
4.96
1.11
47.14
S
81
71
3.75
1.65
1.10
43.85
M
80
9
11.78
3.54
1.18
30.03
M
81
27
5.60
1.18
0.23
21.14
B
80
25
11.33
4.71
0.94
41.60
B
81
76
4.05
2.22
0.25
54.75
CHLORIDE
S
80
26 4105.8
2965.4
581.6
72.22
S
81
0
—
—
—
—
M
80
9
100.67
94.59
31.5.3
93.97
M
81
0
—
--
—
—
B
80
28 3838.2
3105.8
586.9
80.92
B
81
0
--
—
«
—
SILICA
S
80
46
4.30
2.15
0.32
49.94
S
81
71
3.31
2.8 2
0.33
84.98
M
80
15
10.1
1.62
0.42
16.05
M
81
27
8.84
1.53
0.29
17.28
B
80
50
4.77
2.70
0.38
56.65
B
81
76
3.58
3.27
0.38
91.32
333
-------
Table 7-2 (continued)
Statistical Summary of Patuxent River Slack Survey
Data for 1980-1981, Surface, Bottom, and Mid Depths
Variable
Depth
Year
N
Mean
Standard
Deviation
Standard
Mean
Error
Coefficient
of Variation
CHLORA
S
80
66
30.92
60.58
7.46
195.89
S
81
70
26.27
17.20
2.06
65.47
M
80
24
14.83
17.30
3.63
119.98
M
81
27
20.72
19.34
3.72
93.35
B
80
73
11.71
13.57
1.59
115.90
B
81
75
22.40
20.40
2.36
91.05
CHLORAC
S
80
0
—
--
—
--
S
81
61
20.42
15.15
1.94
74.17
M
80
0
—
--
—
—
M
81
24
11.96
15.62
3.19
130.53
B
80
0
—
—
—
—
B
81
67
14.15
13.43
1.64
94.91
PHEOP
S
80
66
4.13
4.25
0.52
103.11
S
81
70
5.82
7.62
0.91
130.98
M
80
24
4.72
3.87
0.79
81.92
M
81
27
5.52
5.60
1.08
106.51
B
80
74
5.52
5.38
0.63
97.36
B
81
75
9.54
15.97
1.84
167.39
334
-------
APPENDIX G
TEMPORAL WATER QUALITY FIGURES AND TABLES
SECTION 8
335
-------
PATUXENT RIVER
SUTION XCF9S75
NAUTICAL MILF O.l
W-AVERAGE 1980
.~-AVERAGE 1981
A-SURFACE
*-B0TT0M
+ - MIN AND MAX
7-00 8•00 9-00
HONTH
PATUXENT RIVER
STATION XDE2599
NAUTICAL MILE 9.6
H-AVERAGF 1980
O-AVFrtAGF 1981
A-SURFACF
JK-BOTTOM
+- MIN AND MAX
^•C
4.00 5-00
r.oo 8 oo
MONTH
9-00 10-00 11-00 12.00
Figure 8-1 Temporal plot of salinity, 1980-1981.
336
-------
PATUXENT RIVER
Q_
0-c
STAT10N NDE53J9
NAUTICAL MILF 13 9
K-AVERAGE 1980
~ -AVERAGE ]9RI
a-SURcACE
*-80TT01
+- M1N AND 1AX
^5.00
5.00
6.00
7.00 8 00
MONTH
9.00
J 0-00
11 .00
1 2.00
PATUXENT RIVER
STA11 OS XDF9401
NAUTICAL MILF 19 P
W-AVERAGE 1980
O-AVERAGE 1981
a-SURFACE
*-B0TT0*1
+ - MlN AND 1AX
°Z.C
5.00
6-00 7.00 8-00 9-00
MONTH
10.00
11 .00
12.00
Figure 8-1 Temporal plot of salinity, 1980-1981
337
-------
PATUXENT RIVER
STATION XED48°.:
NAUTICAL MILE 25 . S
H-AVERAGE »980
O-AVERAGF 1981
^-SURFACE
X-BOTTOM
+ - MI N AND MAX
^J.OO
5.00 6 00
7'00 8.00 9.00
MONTH
i 2.00
PATUXENT RIVER
STAT10N XEDQ490
NAUTICAL Ml L F 30 C
H-AVERAGE 1980
O-AVERAGF 1981
A-SURFACF
3K-B0H0M
+ - M1N AND MAX
^3.00
4.00
5.00
6-00
7.00 8-00 9-00
MONTH
10-00 11.00 I 2 - 00
Figure 8-1 Temporal plot of salinity, 1980-1981.
338
-------
PATUXENT RIVER
MONTH
Figure 8-1 Temporal plot of salinity, 1980-1981
3391
-------
PATUXENT RIVER
1 MTlflN
N A Ml 1( M
xr^ ov:
Mil K
ft -AVFRAGK 19R0
~ A V {- R A F I ,
A r,UR«'A(;K
X-B0U01
+ - M1N KND 1AX
^J.OO
4.00
5-00
7.00 8.00
MONTH
PATUXENT RIVER
STATION XDE2599
NAUTICAL MlLF 9 6
W-AVERAGE 1980
O -AVERAGF Ii
a-SURFACF.
X-BOTTOM
+ * Ml N AND MAX
^J.OO
4-00
6-00
7.00 8.00
MONTH
9.00
10.00
11 .00
12-00
Figure 8-2 Temporal plot of temperature, 1980-1981.
340.
-------
PATUXENT RIVER
ST AT1OM XDEr 53°
NAUTICM MlLF \ '¦
H AVI'RAf.r I WO
fVI.NAU 1 mk ,
A surui:i-
*•BOTTOM
+ - MlN AND MAX
^3.00
4.00
5-00
6-00
7.00 8-00
MONTH
i2.00
PATUXENT RIVER
SMTION XDEJMOi
NAUTICM. MlLF. 19
tE-AVERAGE 1980
~-AVERAGF l 9Kl
a -SURFACF
*• BOTI 0*1
+ - MIN AND MAX
^3.00
4.00
5.00
6.00
7.00 8.00
MONTH
9-00
»0-00
»2 • 00
Figure 8-2 Temporal plot of temperature, 1980-1981.
341
-------
PATUXENT RIVER
01
DO
i- ^
C(D.
CC -
UJ
Q_
LJ O
b'AMos xrn4d°,.
NM'Til'M MIU
U AVIKAT.I I 'hill
avi i<.a 1i r'JM
A JURKAtt"
* B0T101
+- M1N AND MAX
^5.00
4.00
5.00
6.00
7.00 8.00
M0N1 H
9-00
10-00 1 I.00
i2. JO
oc
Z>°
ip
.
01-
UJ
Q_
21
UJO
PATUXENT RIVER
$T A T1 ON XEDP490
NAUTICAL MKF. 150 C
M-AVERAGE 1980
O-AVERAGF I 98i
a-SUR-"ACF
*-B0TTQ1
+- M1N AND 1AX
°3 • 00
5.00
6-00
7.00 8.00
MONTH
9 00
iO 00 i 1 .00 i2.00
Figure 8-2 Temporal plot of temperature, 1980-1981.
342
-------
PATUXENT RIVER
STATION PXT0402
4AUT l r A I. Mil F 3S
4 AVtl.'MU I'lttli
\VI IMM | •»",
SUKI Al t
BOFIOM
HlN AND MAX
^5.00
4.00
5.00
6.00
7-00
MONTH
8-00
9.00
10-00
n .oo
12 '00
PATUXENT RIVER
STAT10N PXT0455
4AU1 1 C\L "lltE 40 G
H-AVERAGE 1980
q1 1 1 r- —¦ ¦ , , 1 , , ,
J. 00 4-00 5-00 6.00 7.00 8.00 9.00 iO.OO 11.00 i?.00
MONTH
Figure 8-2 Temporal plot of temperature, 1980-1981.
343
-------
PATUXENT RIVER
S T A 11 OS
N A U1 I r M.
°XT049A
mi i f r:
H AVl'KMU 1'lKii
^ AVI IM- I I >Ji i
I MIN SNl» 1A\
^.00
4.00
5.00
7 .00
MONTH
9 00
PATUXENT RIVER
sT a T i os ^xior.oj
NAUT1CU MlLF 54.
tt-AVERAGE 1980
O-AVERAGF 198i
+ - MIN AND 1AX
4.00 5.00
6.00 7.00 8.00
MONTH
9 00
iO.oo n oo 12.oo
Figure8~2 Temporal plot of temperature, 1980-1981,
344
-------
PATUXFN1 R'lVFR
MAI KIN
NAIH 11 Al
-------
PA1UXFN1 RIVHR
!' 1 ft I I UN
NAM I |i M
MM
"III!
I
n AVt.KAUl 1'JHO
C> 1VERAGF 1981
A-SUR^ACF
*~B0T T0M
+ - Ml N AND 1Ay
^3-00 4.00 5-00 6.00 T-OO 8.00 9.00 iO 00 11-00 i?-00
MONTH
PATUXENT RIVER
STATION XDc940i
NAUTICM M1LF 19
H-AVERAGF 1980
©-A7ERAGF 198¦
A-SURFACF
X-ROT TDM
+ - M]N AND MAX
^•00
4.00
5.00 6.00 7.00 8 00
MONTH
i 1 00
\2 00
Figure 8-3 Temporal plots of pH, 1980-1981.
34T6
-------
PATUXENT RIVER
l.'AT ION Xh0 AVI NAM I '•>» I
A :.HKI ai I
x nu' MH
+ UN \ND MAX
XN
CL
^•00
4.00
5.00
6-00
7.00 8-00
MONTH
9.00
10 00
I 1 .00
12.00
PATUXENT RIVER
StaTION \ED9'90
NAUTICAL MlLF 30.C
W-AVERAGE 1980
O-AVERAGF 198i
A SURFACE
*-90TT01
+ - MIN 4ND 1AX
a.
°3.00
5.00
7.00 8.00
MONTH
1^.00
Figure 8-3 Temporal plots of pH, 1980-1981.
347
-------
PATUXTNT R I VI"R
MA! I MM
NA1M i( A) Mill T.
I
1
w AVI HAl.r I 'Jill'
0 AVI HAU1 )9i>\
4-SURFACE
3K-B0TT01
+ - MIN AND MAX
^.00
4.00
5.00
6.00
7.00 8.00
MONTH
10-00
n .oo
PATUXENT
RIVER
ST AT 1 ON PXT0455
NAUT1CAL Ml LF 40 C
H-AVERAGF 1980
~ -AVERAGF 1 98 i
+ - MIN AND 1AX
o
o
^.00' 4.00 5-00 6 00 7.00 8-00 9-00 l0.00 11.00 i2
MONTH
Figure 8-3 Temporal plots of pH, 1980-1981.
348
-------
PATUXFNT RIVFR
*.'Al Ihn
NAU f I ' M fill I •*:»
W AVKRAHK 19H0
^ AVrRK't" t*»Hi
+* MIN AND 1A\
^•00
4.00 5-00 6.00
7.00 8 00 9 00
MONTH
J 0.00 i 1 .00 \P. 00
PATUXENT RIVER
VAT10N PXT0C3J
NAUTICAL MILF. 5'
H-AVERAGE 1980
~-AVERAGF 1981
+ - MIN AND 1AX
^.00
4.00 5.00
6.00
7.00 8.00
MONTH
9 00 10-00 H .00 (2.00
Figure 8-3 Temporal plots of pH, 1980-1981.
349
-------
PATUXENT RIVER
V
STAT 1OM \CF9b75
NAUTICAL MlLF 0
W-AVERAGE 1980
~-AVERAGE 1981
+ - IIN AND MAX
°J.OO
4.00
5.00
6.00
7.00 8 00
MONTH
1 1 .00
12-00
PATUXENT RIVER
STATION XDE2599
NAUTICAL MILE 9 C
M-AVERAGE 1980
O-AVERAGF 1981
+ - MI N AND MAX
?5.00
4.00 5.00
7.00 8.00
MONTH
9.00 10 00 I 1.00 12.00
Figure 8-4 Temporal plots of secchi disc 1980, 1981.
350
-------
PATUXENT RIVER
STATION XDE53JQ
NAUTICAL MILF 13
K-AVERAGE 1980
^-AVERAGF 1981
+- MIN AND MAX
^5-00
4.00
5.00
6.00
7.00 8.00
MONTH
9-00
10.00
1 1 .00
PATUXENT RIVER
STA T1 ON XDE9*0i
NAUTICAL MILE 19 ^
K-AVERAGE 1980
^-AVERAGE 1981
+- MIN AND MAX
^.00
4.00
5.00
7.00 8.00
MONTH
9-00
1 I .00
Figure 8-4 Temporal plots of secchi disc 1980, 1981.
351
-------
PATUXENT RIVER
PATUXENT RIVER
MONTH
Figure 8-4 Temporal plots of secchi disc 1980, 1981.
352
-------
PATUXENT RIVER
MONTH
PATUXENT RIVER
MONTH
Figure 8-4 Temporal plots of secchi disc 1980, 1981.
353
-------
PATUXENT RIVER
MONTH
PATUXENT RIVER
MONTH
Figure 8-4 Temporal plots of secchi disc 1980, 1981.
354
-------
PATUXF.NT RIVER
S'ATlflN XO'9r/\S
NAUMCM. 11 Lt 0
B-AVERAGF 1980
C> 1VFRAGI 1 OH I
A MIRI ^^^r
* Minnn
I MIN ^Nil MAN /
/8
5.00
6.00
7.00 8 00
MONTH
PATUXENT RIVER
STATION XDE2599
NAUTICAL M1LF. 9-6
K-AVERAGF 1980
O-AVF-UGF 1981
A-SURFACF
X-B0TT0M
+ - Ml N AND *1AX
^5.00
4.00 TToo
6.00 7.00 8 00
MONTH
9-00 J 0.00 U.00 12-00
Figure 8-5 Temporal plots of dissolved oxygen, 1980-1981.
355
-------
PATUXENT RIVER
'.'Al UN
nmm i< m
XDK. t10
Mil I I 1
n AVMU«r i
OAVERAGF 1
A SURFACc
3K--B0TT01
+ -- MIN 4ND MAX
^3.00
5.00 6-00
7.00 8-00
MONTH
I 0 00 il . 00
i2.00
PATUXENT RIVER
STATION X0F.940i
NAUTICAL IlLF I 9 O
H-AVERAGF 1980
-AVERAGF 1 981
A-SURFACF
*-B0TI0l
+ - UN AND MAX
J. 00 4-00 5.00 6.00
7-00 8-00
MONTH
9 00 10.00 11.00 1 2.00
Figure 8-5 Temporal plots of dissolved oxygen, 1980-1981
356
-------
PAJUXF.NT RIVER
O"
2T».
UJo
o°
X
o
Q
UJo
o
t/)
uo
STAT10N XFD^8Q<;
NAUTICAL M1LF. 25.
H-AVERAGE 1980
O-AVERAGF 1981
a - SURFACE
X-B0U01
+ - Ml N *ND 1AX
^.00
'5-00 6 00
7.00 8 00 9-00
MONTH
I 0-00 I I. 00
12.00
PATUXENT RIVER
v. o
LUO
~o
X
o
Q
UJo
r> ^
o"
ln
tn
S'AMON X£DQ490
NAUTICAL -IILF 30 C
K-AVERAGF 1980
O-AVFRAGF 1981
A-SURrACF
W-BOTTO^t
+ - M1N AND 1AX
°3.00
4.00 5-00 6.00
7.00 8.00 9.00
MONTH
I 0.00 iJ.00 12-00
Figure 8-5 Temporal plots of dissolved oxygen, 1980-1981.
357
-------
PATUXF.N I" RIVKR
^5-00
4.00
5.00
6-00
7-00 8-00
MONTH
9.00
STATION PXT0402
NAUTICAL MILE 35 2
H-AVERAGE 1980
O -.mMAbt-" 1931
A-SURFACF
X-B0TT0M
+- MIN AND MAX
10-00
11.00 12.00
PATUXENT RIVER
STAT1QS °
-------
PATUXF.NT RIVER
ST A1 ION °\TOd9^
NAUT1 CM Ml1 F
H-AVERAGF 19B0
O-AVERAGF 1981
+ - *1] N AND MAX
°^.00
4.00
7 .,00 8.00
MONTH
10 00
(2. CO
PATUXF.NT RIVER
SMTiO^ DXTOC.Oi
NAU1 jCAL *i 1Lr 5
K-AVERAGF I 9B0
O-AVERAGF 190i
+ - Ml N AND MAX
^3.00
4.00
6-00 7.00 8.00 9.00
month
I 0.00 I I .00 12.00
Ftciure 8-5 Temporal plots of dissolved oxygen, 1980-1981.
359.
-------
PATUXFNT RIVER
STATION XC»-"9V5
NAUTICAL MILE 0-
M-AVERAGE 1980
O-AVERAGF 198i
A-SURFACE
k-bqttoi
+ ¦ MlN AND MAX
• 00
4.00
7.00 8.00
MONTH
9-00
10 00
1 ) 00
i 2-00
-1
PATUXENT RIVER
W
o
Or
STATION XDE2599
NAUTICAL MILE 9 G
W-AVERAGF 1980
0-AVF.RAGF I 981
1-SURFACF
X-B0TT0M
+ - Ml N AND MAX
O I
l+
°3.00 4.00 5.00
6-00
7 •00 8-00
MONTH
9 00
10.00 I 1.00 '2.00
Figure 8-6 Temporal plots of dissolved oxygen saturation, 1980-1981
360
-------
(S)
o
or
PATUXENT RIVER
STAT ION XDFSJJ*
NAUTICAL fllLF M °
H-AVERAGE 1980
~-AVERAGF I9«i
A-SURFACt"
*-BOTTOM
M1N \ND MAX
^3.00
5.00 6-00
7-00 8-00 9-00
MONTH '
1 0 • 00 1 1 .00 i. 00
m
o
Or
PATUXENT RIVER
S T A TI ON XDE910»
NAUTICAL MILF 19 Q
H-AVERAGE 1980
~-AVERAGE I 98i
a-SURFACF
X-BOTTQM
+ - MlN AND MAX
^.00
5.00 6 00
7.00 8 00 9.00
MONTH
lO.OO 11.00 12.00
Figure8-6 Temporal plots of dissolved oxygen saturation, 1980-1981
361
-------
o
Or
PATUXFNT RIVER
STATIO^ XF.D^Q,.'
*MUT1CU MIL F. 23
K-AVERAGE 1980
O-AVERAGF 198i
A-SUR^ACF
*-B0T T01
+ - UN AND 1AX
°5 00
'•00 8 00
MONTH
i 1 .00
i 2.00
o
ar
PATUXENT RIVER
5 T AT 10M \ED9*90
NAUTI CM MILF 30 C
K-AVERAGF 1980
^-AVERAGE 198¦
6 -SURFACF
K-B0TTU>1
+- MIN AND MAX
^5.00
'6-00 7 ¦00 8-00 9 00
MONTH
Figure 8-6 Temporal plots of dissolved oxygen saturation, 1980-1981.
362
-------
-1
PATUXENT RIVER
s-i
STATION PXTO'OS
NAUTICAL hi LE 35-^
M-AVERAGE 1980
~-AVKRAGF x 19Pi
^-SURFACE
3K-B0TT0M
+ MIN AND MAX
^5.00 4-00 5.00 6.00
7.00 8-00
MONTH
9-00 10-00 11 .00 12•00
PATUXENT RIVER
STATION °xTOd5o
NAUTICAL 1ILF 40 G
H-AVERAGE 1930
~-AVERAGE 1931
+ - Ml N *ND MAX
^3.00
4.00 5.00
7.00 8-00
MONTH
9-00 10 00 i 1 .00 J 2.00
Figure 8-6 Temporal plots of dissolved oxygen saturation, 1980-1981
363
-------
PATUXENT RJVF.R
LO
o
or
°3• 00 4.00 5-00 6 00 7.00 8.
MONTH
ST ATI0W PXT0494
NAUTICAL MILf" 42.Q
K-AVERAGE 1980
O-AVERAGF 198)
+- MlN AND 1AX
00 9 00
iO 00
i 1 .00
i 2 00
IT
O
CV
PATUXENT RIVER
STATION d X T OGOi
NAUTICAL MILF. 5*.A
X-AVERAGE 1980
O--AVERAGE 1 98 i
+ - MlN AND 1AX
°3.00
5.00
7 .00 fl 00 9 00
MONTH
iO.OO
i 1 .00 I 2 - 00
Figure 8-6 Temporal plots of dissolved oxygen saturation, 1980-1981
364
-------
PA1UXENT RIVER
MONTH
PATUXENT RIVER
MONTH
Figure 8-7 Temporal plots of dissolved nitrite, 1980-1981.
365
-------
PATliXENT RIVER
MONTH
PATUXENT RIVER
MONTH
Figure 8-7 Temporal plots of dissolved nitrite, 1980-1981.
366
-------
PAUJXi Ml K' I v'i.'R
MONTH
PATUXF.NT RIVER
MONTH
Figure 8-7 Temporal plots of dissolved nitrite, 1980-1981.
367
-------
PATUXENT RIVER
"X 00 4.00 5.00 G.00
rT.To «' oo 9'. oo
MONTH
STATION PXT0402
MAUI 1CAL MILE 3b.^
U A \ | R/U.l I *1M (>
~ AVKRA'.r \'W\
A-SURFACF
JK-BOT TOM
+ MlN AND MAX
10.00 II.00 ?2.
PATLXEN1 RIVFR
STATION PXT0455
NAUTICAL MILE 40.6
H -AVERAGE IS80
~-AVERAGE 1981
+ - MlN AND MAX
^$.00 4.00 5.00 6.00
7.00 8-00 9-00
MONTH
10-00 11 .00 12.
Figure 8-7 Temporal plots of dissolved nitrite, 1980-1981.
368
-------
PATUXENT R1\FR
UJ
Ct"
O _
uj2
_jo"
o
to
0£
STATION PXT0494
NAUI 1 CM Mil F. 4? Ci
H M|Hai.| 1 '(Mil
1> AVFRAM 1 UK i
+- H1N AND 1AX
J. 00
4.00
5.00
6 00
7.00 8.00 9.00
MONTH
)0.00 H.00 12.00
Eo-
§»j
_jc
O
to
cn
QO
DATUXENI RIVER
STATION PXT0603
NAUTICAL MILE 54-2
X -AVERAGE 1980
~-AVERAGE 1981
/ \ +- M1N AND MAX
^5.00
4.00
5.00
6.00
7.00 8-00
MONTH
10.00 11 .00 12-00
Figure8-7 Temporal plots of dissolved nitrite, 1980-1981.
36 g_
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PATUXENT RIVER
O -
Q
UJ?
_|0
O
CO
(/)
*> T A T1 OM XCF9575
•JAIJflP.Al MUF 0
»- AVERAGF 1980
>> AVFR^* 19H.
& ;SURFATF
*-oni i riM
I Ml W ANIt "IAV
J • 00
4.00
5.00
6.00 7-00 8-00 9-00
MONTH
10.00 n.00 12.00
PATUXENT RIVER
STATION XDE2599
NAUTICAL MILE 9.6
H-AVERAGE 1980
~-AVERAGE 1981
A-SURFACE
X-BOTTOfl
+ - Ml N AND MAX
.00
4'. 00
5.00
6.00
7.00 8.00
MONTH
9.00
lb.oo i'i.oo Ta.oo
Figure^8-8 Temporal plots of dissolved nitrate, 1980-1981.
.370
-------
PATUXENT RIVER
STATION XDE5339
NAUTICAL MlLF 13.
W AVERAGE 1900
$ AVi:HAOF I0H1
A-SURFACE
*-BOTTOM
+- M1N AND MAX
.00
4.00
5.00
6.00
7.00 8.00
MONTH
9-00
10.00
11 .00
12.00
ol
PATUXENT RIVER
STATION XDE940i
NAUTICAL MILE 19.9
M-AVERAGE 1980
~-AVERAGF 1i
^-SURFACF
3K-B0TT0i
+ - Ml N AND 1AX
CD- |
So"|
UJ'
(— '
<1 '
or
Q
UJ?
'1
°3-00
4.00 5.00 6.00 7.00 8-00 9.00
MONTH
10.00 11 .00 12.00
Figure 8-8 Temporal plots of dissolved nitrate, 1980-1981.
371
-------
PATUXENT RIVER
ol
On
Eo1
Y 'A
_.o ]
_io
O
CO
CO
C\csi
*
* - StJRF Ar-F
+ - Ml N AND 1AX
J. 00 4.00 S.00
7.00 8-00
MONTH
10.00 11.00 12.00
Oo
£ 'H
>• ..
JO
o
CO
CO
£*
PATUXENT RIVER
STATION XED9490
NAUTICAL MILE 30-6
H-AVERAGE 1980
O-AVERAGF 1981
A-SURFACE
^5.00 4.00 5.00 6.00
7.00 8-00
MONTH
9.00
10.00 n .oo 12.00
Figure 8-8 Temporal plots of dissolved nitrate, 1980-1981
372
-------
PATUXENT RIVER
O-
2:
Q
uj£
> .
._io
O
CO
w
o?
STATION PXT0402
NAUTICAL MILE 35-2
K-AVERAGE 1980
0-AVFRAGF 1 9fl 1
A -SURFACF
B-BOHOU
+- MlN AND MAX
^5.00 4.00
5.00 6-00
7.00 8 00
MONTH
9.00 10.00 11.00 12-00
PATUXFNT RIVER
~n
Oo
%
O
i
°1
STATION °XT045!>
NAUTITAL hll.F 40 r.
« -AVERAGF 1980
0 AVKRASr I ,
Ml N AND MAX
°/ 00
4.00 5.00
6.00 7.00 8.00 9.00
MONTH
10.00 n .00 12.00
Figure 8-8 Temporal plots of dissolved nitrate,, 1980-1981.
373
-------
PATUXFNT RIVER
->-) STATION
MALM CM. MIlF 42 <1
W AVrftA'iF IflflO
t Wl I'AM I ' I
' 4- • fIJN AND *1AX
LDo •
5ci
—o-
E-1
o "1
u?
.
o
LO
CO
STATION PXT0603
NAUTICAL MILE 54-2
H-AVERAGE 1980
~ MVERAGF 1 98 t
+ - Ml N AND 1AX
PATUXENT RIVER
^5.00
4.00 5.00
7.00 8.00
MONTH
9.00 10.00
I.00 12.00
Figure 8-8 Temporal plots of dissolved nitrate, 1980-1981.
374
-------
Org
21
O •.
r°
r
-JO
O
CO
CO
PATUXF.NT RIVER
STATION XCFSSrS
NAUTICAL NILE 0.1
K-AVERAGE I960
^-AVERAGE 1981
A-SURFACE
*-B0TT0>1
+ - M1H AND HAfc
^.00
4.00
5.00
6.00 f.00 8-00 9.00
MONTH
10-00
11 .00 T2.00
Ocu
Z-
o •.
r
S2
>• .
_io
o
CO
to
Qin
PATUXENT RIVER
+
X
STATION XDE259S
NAUTICAL HILE 9-6
H-AVERAJE 1980
^-AVERAGE 1981
A-SURFACE
K-B0TT0M
+ - rilN AND MAX
00 4.00 5-00 S-00
7-00 8.00
MONTH
9-00
10.00 11 .00
Figure 8-9 Patuxent River Temporal Plot of Dissolved Ammonia
375
12.00
-------
2:-
O V
_jo
o
CO
CO
o
PATUXENT RIVER
STATION XDE5339
NAUTICAL MILE 13-9
H-AVERAGE 1980
~-AVERAGE 1981
a-SURFACF
m BOT t 01
+- MIN AND MAX
.00 4-00 5 00 $.00 7.00 8.00 9-00 10-00 11-00
MONTH
j 2.00
OCM
£o-
O •.
21°
o
11 iQ
> .
JO
O
CO
CO
PATUXENT RIVER
STATION XDE9401
NAUTICAL MILE 19.9
H-AVERAJE 1980
~-AVERAGE 1981
A-SURFACE
*-80TT0«
+ - MIN AND MAX
^•00
4.00
5.00
6.00 7.00 8.00
MONTH
9.00
10.00 1 'l . 00
Figure8-9 Patuxent River Temporal Plot of Dissolved Ammonia
376
12.00
-------
PATUXENT RIVER
MONTH
^J.OO
PATUXENT RIVER
STATION XE09490
NAUTICAL MILE 30-6
K-AVERAGE I9P0
~-AVERAGE 1981
A-SURFACE
M-B0TT01
+ - M1N AND MAX
4.00
5.00
'6.00
7.00 8.00
MONTH
9-00
10-00 11.00
12.00
Figure 8-9 Patuxent River Temporal Plot of Dissolved Ammonia
377
-------
PATUXENT RIVER
PATUXENT RIVER
MONTH
Figure 8-9 Patuxent River Temporal Plot of Dissolved Ammonia
378
-------
PATUXENT RIVER
MONTH
2 PATUXENT RIVER'
cy"
rs. oo
4.00
s'.oo
6.00
7.00 8.00
MONTH
9.00
STATION PXT0603
NAUTICAL MILE 54.2
W-AVERAGE 19e0
~-AVERAGE 19B1
+- MIN AND MAX
10•00 11 .00
12 .00
Figure 8-9 Patuxent River Temporal Plot of Dissolved Ammonia
379
-------
V
o
r ¦
.
K.
ol
Z
UJ '
O i
o
PATUXENT RIVER
STATION XCF9575
SAUTICA! MILE 0
tt AVERAGF 1980
O-AVKRAGf- I9H,
A-SURF^CF
*-B0T T01
+ - MIN ANO I4*
ZiO
<•0
2°
O
°5.00 4.00
S.OO 6-00
7.00 8.00
MONTH
9.00 10 00 M .00 '2-00
-1
^61
o
z:
PATUXENT RIVER
TTATIO** XDE2599
NAUTICAL MILE 9-6
K-AVERAGE 1980
O-AVERAGE 1981
A-SURFACE
X-B0TT0M
+- MIN ANO MAX
ol
z
UJ
CD
O
(E-r
h- ^
•— o~l
o
J.00 4.00 5.00 6.00
7.00 8.00
MONTH
9.00
10.00 11.00 12-00
Figure 8-10 Patuxent River Temporal Plots of Total Organic Nitrogen.
380
-------
-1
O I
PATUXENT RIVER
STATION XDE5339
NAUT1CAL M'LE 1
H-AVERAOF 1989
C> AVERAi'K 1 i
V-SURFACF
*-BOT TOM
+- M1U ANO 1AX
^5.00
5-00
6.00 7.00 8-00 9-00
MONTH
10 00 1 I .00 12-00
o '
CD
r
PATUXENT RIVER
STATION XDE9401
NAUTICAL MILF. 19.9
H-AVERAGE 1980
O-AVF.RAGF 1 981
A-SURFACE
5K-B0TT0M
+ - MI N AND 1AX
o1
UJ ,
O [
o |
cc* ¦
:
m k
Z«£)
|