PB03-253195
Ware River Intensive Watershed Study
2. Estuarine Receiving Water Quality
Virginia Inst. of Marine Science
Gloucester Point
Prepared for
Environmental Protection Agencv, Annapolis,
Chesapeake Bay Program "
Aug 83
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4. TITLE AND SUBTITIF
Ware River Intensive Watershed Study -
2. Estuarine Receiving Water Quality
TECHNICAL REPORT DATA
(Please read Ihsinicr.om un Hie ret cne before complctmrl
. REPORT NO.
EPA-600/3-83-Q78b
S REPORT DATE
. August 1983
6. PERFORMING ORGANIZATION CODE
VIMS
AUTHORIS) . | '
Cindy Bosco, G.F. Anderson and Bruce Neilson
8. PERFORMING ORGANIZATION REPORT NO.
PB83 253195 _
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Virginia Institute of Marine Science
College of William and Mary
Gloucester Point, VA 23062'
10. PROGRAM ELEMENT NO.
11. CONTRACT/GRANT NO.
806310
12. SPONSORING AGENCY NAME AND ADDRESS
Chesapeake Bay Program
U.S. Environmental Protection Agency, ORD
2083 West1Street j
Annapolis, MD 21401 I
13. TYPE OF REPORT AND PERIOD COVERED
14. SPONSORING AGENCY CODE
EPA/600/05
15. SUPPLEMENTARY NOTES
I
16. ABSTRACTThe Ware River Intensive Watershed Study contains results of runoff from small
catchments, instream transport of runoff and the impacts on estuarine water quality,
which are contained in two volumes: 1. Nonpoint Source Pollution and 2. Estuarine Re-
ceiving Water Quality..
The', Ware; River is a relatively "clean" estuarine system. However, during summer
nonths some of the'nutrients, particularly inorganic phosphorus and organic nitrogen,
achieve levels associated with moderate :enrichment. The Ware is typical of other small
tributaries of Chesapeake Bay: nutrient 'levels are higher ,at low tide, the estuary is
nore homogeneous laterally than longitudinally, and vertical gradients exist for dis-
solved oxygen, total phosphorus, and suspended solids. /
The estuary is generally phosphorus:limited, except during the annual spring phyto-
plankton blooms (April 1979 and March.1980) when uptake of inorganic nitrogen by plank-
ton causes the system to be nitrogen limited.
Impacts of nonpoiht source pollution are slight and shortlived in the estuary.
This appears t<2 be due to dilution by Bay; waters and sedimentation in "the upstream
narshes. Thus, impacts typically are observed only in the shallow upstream portions Of
the estuary.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.lDENTIFIERS/OPEN ENDED TERMS
c. COSATi Field/Group
18. DISTRIBUTION STATEMENT '
Release to public
19. SECURITY CLASS iTIitl Kfporl/
Unclassified
21. NO. OF HAGfcS
130
30. SECURITY CLAF
Unclassified
33. PRICE
EPA Form 2220-1 (Rซv. 4-77) PREVIOUS EDITION is OBSOLETE
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EPA-600/3-83-078b
August 1983
WARE RIVER INTENSIVE WATERSHED STUDY
2. ESTUARINE RECEIVING WATER QUALITY
by
Cindy Bosco
Gary F.- Anderson
| Bruce Neilson j
Department of Estuarine Processes and Chemical Oceanography
' Virginia Institute of Marine Science
College of William and Mary
Gloucester Point, VA 231062
Grant No. 806310
Co-Project Officers
James Shell j Virginia State Wat'er Control Board
James Smullen, EPA
U.S. Environmental Protection Agency
Chesapeake Bay Program
2083 West Street,
Annapolis, Maryland 21401
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NOTICE
This document has been reviewed in accordance with
y.S. Environmental Protection Agency policy and
approved for publication. Mention of trade names
or commercial products does not constitute endorse-
ment or recommendation for use.
1i
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ABSTRACT
The Ware River Intensive Watershed Study contains results of
runoff from small catchments, instream transport of runoff and
i^he impacts on estuarine water quality, which are contained in
two volumes: 1. Nonpoint Source Pollution and 2. Estuarine
Deceiving Water Quality.i
1 I " ~ ' '' '"' '
Estuarine Studies '<
I
The Ware River is a relatively "clean" estuarine system.
However, during summer months some of the nutrients,
particularly inorganic phosphorous and organic nitrogen, achieve
levels associated with moderate enrichment. The Ware is typical
of other small tributaries of Chesapeake Bay: nutrient levels are
higher at low tide, the estuary is more homogenous laterally than
longitudinally, and vertical gradients exist for dissolved
oxygen, total phosphorous, and suspended solids.
The estuary is generally phosphorous limited, except during
the annual .spring phytoplankton blooms (April 1979 and March
1980) when uptake of inorganic nitrogen by plankton causes the
system to b'e nitrogen limited. /
Impacts of nonpoint source pollution, are slight and short-
lived in the estuary. This appears to be due to dilution by Bay
waters and sedimentation in the upstream marshes. Thus impacts
typically are observed only in the shallow upstream portions of
the estuary, , \
iii
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CONTENTS
Page
ABSTRACT. ...,.,..: i . . , '.. ill
LIST OF FIGURES * i . .,i . v11
1 ' ! ' ' '
LIST OF TABLES J !, , i:. 1x
" i ' |
ACKNOWLEDGEMENTS . * 1 i . .. i '., . *
-SECTION 1 1
1.1 INTRODUCTION. . 4 ;. 1
1.2 DESCRIPTION OF THE STUDY AREA ,. 3
1.3 CONCLUSIONS. ..*.,( 6
SECTION 2
2.U ESTUAR'INL' FTKLD STUDY AND RESULTS ,; * 8
2.1 METHODS AND MATERIALS FOR ESTUARINE FIELD SAMPLING v. 9
2.1.1 ESTUARINE HYDROGRAPHIC DATA COLLECTION.... I. 11
2.1.2 OTHER SPECIAL ESTUARINE SAMPLING EQUIPMENT... 12
2.1.3 STATISTICAL METHODS 14
2.1.4 QUALITY CONTROL DATA i' '.:. 15
2.2 INTENSIVE SURVEYS
2.2.1 1979 INTENSIVE SURVEY. . i ... i i .;.. 17
2.2.2 1930 INTENSIVE SURVEY. 29
2.2.3 1981 INTENSIVE SURVEY. '; 38
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CONTENTS (Continued)
2.3 TREND ANALYSES: APRIL 1979 - JULY 1981.*.....' I ,. -51
2.4 SPRING SURVEY, 1981 4 .. $6
2.4.1 TWO DAY Vs MONTHLY SLACKWATER SAMPLING TECHNIQUES..'. 82
i > ' . ' ' ' I I
2;5 ASSESSMENT OF STORMWATER IMPACTS IN THE ESTUARY i*.. 84*
"' ' ' " !
2.6 "WET"/"DRY" HIGHWATER SLACK SURVEYS...... 4 *... i.,..,.
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LIST OF FIGURES
Number ' Page
1 Location of the Ware River Basin ;.. A
2 Map of Ware River Sampling Stations .... 10
3 Tidal variation in salinity during August 1979 Intensive
Survey........ iป J 18
4 Average total Kjeldahl nitrogen concentrations in the brackish
region (W5j WFM1, WBS1)[ August 1979 Intensive Survey.. 22
5 Average total ammonia-nitrogen concentrations in the brackish
region (W5, WFM1, WBSl), August 1979 Intensive Survey 23
6 Average total phosphorus concentrations in the brackish
region (W5, WFM1, WBSl) and in two streams (STR3, STR4),
August 1979 Intensive Survey 24
7 Average suspended solids concentrations in the brackish region
(W5, WFM1, WBS1), August 1979 Intensive Survey 25
8 Dissolved oxygen percent saturation at transect W3,
August 1979 Intensive Survey 27
9 Phosphorus specie mean concentrations, July 1980 Intensive
Survey 31
10 Nitrogen species mean concentrations, July 1980 Intensive
Survey ......; {.....- .:* 33
11 Average TN:TP ratios, July 1?JO Intensive Survey 34
12a Chlorophyll-a concentrations at FM2 and FM3, July 1980 Intensive
Survey l..\ /. 36
12b Chlorophyll-a concentrations at BS6 and BS8, July 1980 Intensive
Survey... .\ .', , /. k 37
13a Average salinity concentrations, March 1981 Intensive Survey... 39
13b Average silicate concentrations, March 1981 Intensive Survey... 39
14 Average chlorophyli-a''concentrations, March 1981 Intensive
\ Survey l.J 41
15 Average carbonaceous biochemical oxygen demand, March 1981
\ Intensive Survey :...!... 42
16 Average total filterable solids, March 1981 Intensive Survey... 43
17 Phosphorus specie mean concentrations, March 1981 Intensive
', Survey. '. .\ * 44
18 Nitrogen specie mean concentrations, March 1981 Intensive
Survey 1 ....,...., 45
I9a Average TN:TP ratios, March 1981 Intensive Survey.\... 47
19b Average DIN:P04 ratios, March 1981 Intensive Survey 48
20 Average TOC concentrations,March 1981 Intensive Survey.. 49
21 Time-series plot of chlorophyll-a concentrations', WIT, WBS1
and STR4 ;.... i ; i...... k 52
22 Time-series plot vof temperature, WlB and WBS1 63
23 Time-series plot oฃ carbonaceous biochemical oxygen demand,
WlB and WBSl '.'.*.., i '.. i......^ J 55
24 Tine-series plot of percent dissolved oxysen saturation at
WBSl and WlB i i t, 56
25 T^ime-ecries plot ot total phosphorus at WlB, WBSl and STR3 58
26 Time-series 'plot of dissolved silica at WBSl and WlB........... 59
vii
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LIST OF FIGURES(cot.:lnued)
Number Page
27a Time-series plot of nitrogen specie concentrations, WIT 60
27b Time-series plot of nitrogen sptcie concentrations, WBS1 61
27c Time-series plot of nitrogen specie concentrations, STR4. 62
27d Time-series plot of nitrogen specie concentrations, STR1}...... . 63
28 Tira^series plot of total filterable solids at WIT, WBS1, STR4.65
29 Time-series temperature plot during 1981 Spring Survey .-'67
30 Timte-series plot of salinity concentrations during 1981 Spring ;
Survey i 68
31 Time-series plot of dissolved oxygen percent saturation during ;.
1981 Spring Survey .. 69
32d Time-series histogram of nitrogen specie concentrations at
Goshen during 1981 Spring Survey 71
32b Time-series histogram of nitrogen specie concentrations at '
Pig Hill during 1981 Spring Survey 72
33a Time-series histogram of phosphorus specie concentrations it
Goshen during 1981 Spring Survey..... 73
33b Time-series histogram of phosphorus specie concentrations at
Pig Hill during 1981 Spring Survey..! ;.,. 74
34 Tims-series plot of TN:TP ratios during 1981 Sprii.ซj Survey.....;75
35 Time-series plot of chlorophyll-a concentrations during
1981 Spring Survey ;.. .' 75
36a Phytoplankton cell counts at Goshen during 1981 Spring Survey.*?78
36b Phytoplankton cell counts at Pig Hill during 1981 Spring Survey 79
37 Time-series plot of dissolved silica concentrations during
1981 Spring Survey . 80
38 Time-series plot of total suspended solids during 1981 Spring
Survey ;..... .81
39 Rainfall and baseflow during study period, 1979-1981 85
40 Relationship between dissolved osygen percent saturation and
rainfall during Stormwater Survey,1980 .,87
41 Dissolved oxygen percent saturation during "Wet" and "Dry"
slackwater surveys .92
42 Total suspended solids concentrations during "Wet" and "Dry"
slackwater surveys 93
43 Dissolved orthophosphorus concentrations during "Wet" and .:,
"Dry" slackwater surveys 95
44 Relationship of nitrite+nitrate nitrogen to rainfall (cm) in
upper estuary. 96
45 Current speeds (m/sec) at BS2 and BS6 during marsh study 98
46 Gonentrations of total suspended solids and silica at BS2 ;
during marsh study.J............ 1 ..100
47 Concentration of total suspended solids at BS6, marsh study....101
48 Concentration of dissolved silica at BS6 during marsh study....110
viii
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LIST OF TABLES
Number Page
1 Quality Control Data from 1980 and 1981 Intensive Surveys..;..16
2 Salinity Differences Between Surface and Bottom Samples During' /
1979 Intensive Survey ........ i..... 20
Comparison of Monthly Averaged Composite Sample Values vst .,
Monthly Slackwater Values* , 83
Comparison of Average Salinity and Daily Discharge Between )
Wet" and "Dry" Slackwater Surveys........:............... j;. ^ ,9l
Chemical Evidence for a Turbidity Maximum...,/ ...i.105
ix
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ACKNOWLEDGMENTS
The authors wish to thank Don Campbell and David Krantz for
their technical expertise and assistance throughout the project.
The study would not have been possible without their good spirits
and perserverance while collecting over 100,000 samples in the
rain, snow and mosquito-fladen weather*
i
We,3130 extend appreciation to Betty Sailey, Cathy White and
Sam Wilson for their long and oftentimes late hours analyzing
the samp.les.
Finally, we would like to thank Maxine Smith for her patient
typing of the manuscript.1
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SECTION 1
1.1 INTRODUCTION
i
The Ware River Study is one of five intensive watershed
(Studies funded ( by the Chesapeake Bay Program of the U.S.
Environmental Protection Agency. In all five basins small
catchments are being monitored to determine the quantity and
quality of runoff for the major land uses and physiographic
features of the Chesapeake Bay drainage basin. These :data will
be used to calibrate mathematical models of land runoff: which in
turn 'will be used to determine the quantity of pollutants
entering Chesapeake Bay from nonpoint sources and to examine how
these loads are likely to vary as land uses change, in the
future. Results from the nonpoint source study are contained in
a companion report, Ware River Intensive Watershed Study 1_^
Nonpo'int Sources.
' I *
In the Ware system and in the two Maryland watersheds,
estuarine water quality is being studied to determine how it is
affected by runoff. The Ware River is relatively clean, and to
a certain extent, it serves as the "control" against which more
impacted systems can be compared. At the beginning of this
study relatively little data was available on the Ware R:Lver; it
was not polluted so it had not been the subject of extensive
monitoring in the past. Therefore the Ware study includes
elements to characterize seasonal, ' tidal, diurnal and other
variations so that the effects of stormwater runoff could be
separated from other features,. The information gained in this
study will provide us with a better understanding of the nature^,
extent and duration of stormwater impacts on estuarine water
quality. In addition, the field data will be used to calibrate
a series of models which will simulate runoff generation and its
transport through the streams and into the estuary.
Seqtion 1, a synopsis of the report, contains a description
of the study area and conclusions from the 27-month
investigation. In the second section, details are presented on
the hydrography and water quality of the receiving waters and the
methods used in collecting the data. Section 2.2 discusses
diurnal trends in the estuarine water quality from measurements
made! aroundj-the-clock during intensive surveys, the first of
which took place during the summer of 1979. Seasonal trends in
estuarine water quality were studied by frequent high water slack
surveys and is included in Section 2.3. The characteristics of
the transition zone from the freshwater flowing streams to the
tidally influenced; brackish waters .of the estuary .is also
described in this section, along with impacts oฃ stormwater upon
the area. A number of incidental topics and findings are
presented, including a discussion of quality control and a
1 .":
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comparison of automatic vs. discrete water sampling techniques.
The remainder of the report includes references and a series
of appendices containing supporting material. Sampling stations
are described in Tables A-l and A-2; the dates of the slackwater
surveys are given in Table A-3. Since the focus of the field
efforts varied, all stations were not occupied during each study.
Table A-4 gives the station coverage for slackwater, intensive
and stormwater runoff surve'ys.
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1.2 DESCRIPTION OF THE STUDY AREA
The Ware River drainage basin lies on the Middle Peninsula
of Virginia between the York and Rappahannock Rivers, as shown in
Figure 1. The Ware, along with the Severn, North and East;
Rivers, debouches to Mobjack Bay on the southwestern shore of
Chesapeake Bay. Beaverdam Swamp and Fox Mill Run are two,
freshwater tributaries which drain the upper reaches of the basin
and provide nearly continuous flows to the estuary. In addition
to the two main stems of the river, two small sub-basins drain .;
into man-made impoundments, Cow Creek Pond and Robbins Pond,
before discharging to the tidal waters of Beaverdam Swamp and
Wilson Creek respectively!. The freshwater streams generally are
shallow (less than 1 meter deep) and not especially wide (usually
less than 4 meters). The channels are sinuous, frequently:
braided and often interrupted by beaver dams, especially in the
headwaters. .
Tidal effects are observed at the Route 14 crossing of
Beaverdam Swamp and just downstream of the Route 17-Business;
crossing of Fox Mill Run. In the transition zone the salinity;
gradients are;large and the channels follow a serpentine course
through extensive tidal marshes on either side of Deacon's Neck.
The Ware proper is formed by the confluence of these two tidal
streams at Warehouse Landing. The main channel of the estuary is;
broad and shallow and is approximately 9i,6 km long. The river.
depth at Mean High Water varies from 8 meters at the mouth to
less than 1.5 m near Warehouse Landing. The channel margins ?nd
subtidal flats are generally narrow, making up less than 20% of"
the river suface area. Salinities usually are 17-21 parts per'
.thousand (ppt) at the mouth, and reflect the strong influence of,
Chesapeake Bay. Salinities at the confluence range between 6 and
17 ppt showing the influence of runoff. -,
The drainage area of the Ware is 174 square kilometers.
Land use in the basin is rural, with over 70% of the land
occupied by forests. Agriculture, primarily rowcrops with annual
rotation of corn and soybeans, account for about 12% of the totalJ
land area. Residential and commercial uses occupy only about.
7,2% of the basin; the majority of this development is at
Gloucester Court House, located near the center of the watershed.
The single point source in the basin, a sewage treatment plant
serving Gloucester, dicharges to Fox Mill Run approximately ;
570,000 liters per day of!secondary effluent about a half"
kilometer above the tidal reaches.
\ The freshwater discharge entering the Ware River is small
relative to the volume of the estuary. The long term average
discharge at the USGS gaging station near^ Ark, Va. on Beaverdam
Swamp is 0.21 cubic meters per second. The average annual .
rainfall is 111 cm based on a thirty year record for 27 gages in
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WARE RIVER BASIN
LOCATION- GLOUCESTER COUNTY,VA.
APPROX. AREA-
194 km2 DRAINAGE BASIN
20 km2 ESTUARY
174 km* TOTAL
CHESAPEAKE
EAY
5 Ml.
10 KM
FIGURE 1. Location of the study area, shaded portion delineates drainage boundaries of the Ware River watershed.
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Virginia's coastal plain!(U.S. Environmental Data Service, 1979).
Monthly average rainfall is fairly uniform and ranges from about
7 cm in April to nearly 12 cm in July. Although rainfall is high
during summer months, monthly mean discharges are lowest then,
presumably due to high rates of evaporation and transpiration.
Meteorological conditions during the study have been somewhat
anomalous. In general 1979 was a wet year and 1980-1981 was dry.
Also the snowfall during the first winter was exceptionally high
for this area and was greater than any since records have been
kept; Although both total rainfall and stream discharge for 1979
were high (see Figure 39), the rainfall was unevenly distributed
throughout the year. For example, the rainfall during September
and November 1979 was the highest for the years 1966 through
1979, while the rainfall for December 1979 was the lowest for
that mpnth during tjie same period. Additionally, during the
first,14 months there was a 33.4 cm surplus of rainfall compared
to the average of 128.8 cm expected for Tidewater (based on data
1940-1970), while during the latter 13 months there was a 37.8 cm
deficit in rainfall. As a result of the draught, Beaverdam Swamp
reached zero discharge in late July 1981, the first time this has
occurred since j 1953 (USG3, 1981).
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Ii3 CONCLUSIONS
Results from the 27-month study showed water quality in the
Ware Ritfer to be relatively non-degraded. The broad reaches of
the estuary are dominated by Chesapeake Bay waters and are rather
homogeneous laterally and longitudinally. However, upstream in
the narrow tidal marsh regions, nutrient rich conditions exist,
and concentrations generally decrease with distance downstream,
indicating that1 advective diffusion plays a major role in
determining overall water quality. The estuary is generally
phosphorus lirjilted, except on a few occassions and in a few
locations. For example, during the annual spring phytopiankton
blooms, uptake of inorganic nitrogen by plankton causes the
system to become nitrogen limited. Also, Fox Mill Run, the only
tributary containing a point-source (57,000 liter per day
secondary sewage treatment plant) contains elevated nutrient
concentrations and is nitrogen limited year round due to the
effects of phosphorus rich sewage.
I ;-'.
The Ware River is typical of many shallow subestuaries that
drain the coastal plain. During low flow conditions, freshwater
inputs to the estuary are insignificant. During high flow
conditions, 'vertical stratification may exist in the downstream
portion! of the estuary, but the gradient is not strong (<2 ppt
salinity). The freshwater to saltwater interface shifts over
several kilometers in the narrow upctream reaches in response to
freshwater inputs, arid a turbidity maximum was found to exist in
at least one of the tributaries, Beaverdam Swamp.
Distinct seasonal patterns were evident: nutrient
concentrations for total phosphorus and nitrogen concentrations
in the estuary were greatest during the summer season; dissolved
oxygen levels were lowest at that time. Results from the trend
data also suggested that increased nutrient concentrations in the
spring and fall were generally due to runoff contributions, arid
inputs in the form of marsh debris. During the summer, or times
of low flow and high temperature, nutrient cycling and release
from the sediments appeared to be the primary factor controlling
nutrient levels. i
i !
Chlorophyll-a exhibited a spring maximum, especially during
1979 and 1980. Phytopiankton cell counts showed diatoms to be the
'dominant spring organism (primarily Rhizosolenia and Nitzschia)".
.During tjie spring of ?981, the typical chlorophyll-a maximum was
not observed. This was presumably due to the drought conditions
which resulted in lesser amounts of dissolved silica introduced
into the estuary from' baseflpw.
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Assessment of stormwater impacts ih the estuary revealed
that rainfall of 0.5 in (1.3 cm) or more resulted in measurable
changes in estuarine water quality. Suspended solids and
nitrite+nitrate nitrogen concentrations increased, whereas
dissolved oxygen (measured as percent saturation) tended to
decrease following major storms. The extent and duration of
nonpoint source pollution varied greatly dependent upon the
amount and intensity of rainfall, and time of year. Generally,
responses in the estuary were short-lived; nutrient loadings
were offset by dilution upon entering the broad reaches of thp
estuary.
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SECTION 2. ESTUARINE FIELD STUDY AND RESULTS
The Ware Rivet is typical of other small estuaries
drain the coastal plain.; Lowjdensity residential housing peppers
the shoreline. Because of the dearth of population and industry
along the river, ntany of the well-known environmental problems of
pollution are absent. Since the Ware River is a fairly "clean"
estuary, it. is a good system in which to assess the impacts of
nonpoint source (NFS) pollution upon the water quality of an
estuary. To accomplish this, it was necessary to ascertain the
existing regime of nutrients (through determination of descriptive
normsj and causal relationships, A baseline was established
initially by conducting a series of semi-monthly highwater slack
(HV^S) surveys. Such information serves as a reference to which
perturbations in the nutrient levels can be compared.
' The effects of nonpoint source pollution, the particulate
matter and associated nutrients that are in runoff from the land,
may play an important role in the productivity of small coastal
plain estuaries. The significance of increased nutrient levels
upon the receiving waters has been discussed by many authors
(Ketchum^ 1967; see also Neilson, 1980). Few other studies have
attempted to address nutrient levels in the Ware River estuary.
The.| Virginia State Water Control Board (SWCB) has routinely
monitored one of the tributaries, Foxraill Run, for fecal
coliformSr various nutrients, dissolved oxygen, pH and
alkalinity since wastewater i is discharged into the stream.
In April, 1979, the Department of Estuarine Processes of the
Virginia ; Institute of Marine Science, College of William and
Mary; irjitidted a two year investigation of the Ware River
Watershedj funded by the Environmental Protection Agency's
Chesapeake Bay Program. The^primary objectives of the estuarine-
research' effort were to provide a description of the hydrography
and water quality and !to as'certain the temporal and spatial
response of the estuary to runoff. The results of the estuarine
monitoring will be presented in terms of trends, in particular
seasonal patterns, and intensive surveys, which were conducted to
define spatial distribution of nutrients as well as solar, tidal
and other die! processes in the estuary. The estuardne response
to runoff, especially the variations^ which occur in the
freshwater to saltwater 'transition zone, are discussed in Section
2. ' ' ' '
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2*1 METHOD'S AND MATERIALS FOR ESTUARINE FIELD SAMPLING
Sampling stations (Figure 2) were established in the Ware
River, first, on the basis of the probable value of the
hydrographic and water chemistry information they would provide,,
and second, on the ease of access to the area since the estuary
is extremely shallow in the upper reaches. Stations were located;
by meanp of buoysf markers and sitings off landmarks.
Surveys were conducted with 18 1/2' T-Birds outfitted with
either single or twin outboard engines. Water was pumped onboard
using a Rule Bilge Pump (750 GPH), and bottles were filled
according to the schedule below once the lines had been cleared
at each station. In case of pump failure, samples were collected
using a Frautschy bottle (a modified Van Dorn discrete water
sampler).
DO: 125 ml glass bottles -~
SALINITY: 125 ml glass bottles V
I . . ' .'
NURIENTSt 2L Nalgene containers
pH/ALKALINITY/SS: 500 ml brown Nalgene bottles
CHLOROPHYLL: 250 ml brown Nalgene bottles "
BODS: 300 ml glass BOD bottles '
/ *
UBOD: 2L Nalgene containers
The field program in the freshwater portions of the estuary
involved little mechanical equipment; all equipment was serviced
and Calibrated before field usage. Field sampling techniques
were selected to insure representative sampling. ฃ
Temperatures measurements in the water column wore taken
using an Applied Research Austin (ARA) Model ET 100 Marine
temperature sensor. Accuracy of the instrument is reported to be
0.1 C. The instrument was tested and recalibrated, when
necessary, before each survey. Dissolved oxygen samples were
"pickled" in the field (manganese suifate solution followed by
alkali-iodide azide reage.nt)! and titrated in the laboratory using
the azide modification of the Winkler methodi
A list of chemical parameters, methods of analysis, and
STORET numbers foir each ^ariable are listed in Volume 1.
Nonpoint Sources. i j :;
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Figure 2. Ware River cstuarinc and Crcshwater stream station locations.
10
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2 + i. .1
ESTUARINE HY.DROGRAPHIC DATA COLLECTION
Bathymetric data was obtained along 15 different transects
in the Ware River, during 1979-1980 using a Raytheon fathometer
(see Appendix A-5). Cross-sectional areas are listed in
Appendix A-6. ' / I
Current Meter Information
General Oceanic current meters (recording at 6j min intervals
for a minimum of 8 tidal cycles) were deployed in the Ware River
estuary in August, 1979 and;July, 1980. During the first year,
lateral as well as longitudinal and vertical data was collected.
Information collected indicated that water movement was fairly
uniform across the channel, therefore during the second year,
all current meters were placed in the center of the channel but
spanned a greater longitudinal distance.
Tide Gage Information
Two tide gages were installed on piers in the Ware River at
rerrnile 1.3 and 5.3. ' Tide gage information was recorded
Results indicated
was an average tidal range of 0.76 m at the
and 2). jhigh tide occurs approximately 35
minutes after the times reported for Hampton Roads (Sewell's
Point) by the U.Sx. Department of Commerce,/ National Oci-anic and
Atmospheric Administration.! However, a /variance of 71 minutes
was found, depending on wind conditions and other factors.
Tid'al information for 1979 and 1980 has been recorded on magnetic
tape and forwarded to SWCB. 1
r
cocomitant with current meter recordings,
that l)"i there
downstream gage
11
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2.1.2 OTHER SPECIAL ESTUARINE SAMPLING EQUIPMENT
PLANKTON ANALYSES
Zooplahkton and phytoplankton were collected seasonally from
at least three of the slackwater stations located in the main
channel of the estuary,' .:
PhytoplanktQn: .
Phytoplankton samples were pumped into 2-liter plastic
containers and placed on ice until brought to the laboratory ;for
analysis. ' ' >
i
phytoplankton samples were first examined and enumerated
with an epi-fluorescent microscope using a proflavin-modified
Acridine-orange direct count method (Hobbie, et al., 1977;
Watson, et al., 1977) and categorized by percentages into major
groups (blue-green algae, cryptomohads, prasinophytes,
heteroflage'llates, green flagellates, dinoflagellates, diatoms
and miscellaneous).
Carbon :ontent determinations were then obtained from the
phytoplankton samples using dry and ash-free weight measurements
according to the procedures outlined in Standard Methods (APHA,
1975) arid in the EFA Biological Field and Laboratory Methods
(U.S. EPA, ^979).
Zooplankton:
Zobplankton were collected in a Clarke-Bumpus sampler using
a #20 mesh (76 u) net. At each station a minimum of 200 liters
of water were tov/ed through. Samples were taken throughout the
water column (oblique samples) with equal towing time at each
depth. Samples' were placed on ice for transport to the
laboratory where biomass (carbon-content) determinations were
performed as described for phytoplankton above.
PARTICLE SIZE DISTRIBUTION
/
Particle size distribution samples were taken seasonally at
all estiiarine stations) using a modified-clam bottom grab.
Samples were 'analyzed for total ,(undigested) and inorganic
(digested) particle sizes on a TA-2 Coulter Counter with
population assessor. Organic values were obtained through
calculation. I
-------
BED SEDIMENT ANALYSES
Bed sediments were sampled seasonally at all estuarine
stations; samples were analyzed for total and inorganic carbon
using an induction furnance and gasometric carbon analyzer
manufactured by the Leco Corporation. Organic carbon values were
obtained through calculations. Total sulfur analyses were also
run on samples using the Leco induction furnance.
SEDIMENT OXYGEN DEMAND
The apparatus used for determining sediment oxygen demand
consisted of a cylindrical chamber fitted with' a self-contained
battery-powered stirrer and a dissolved oxygen probe (YSI-15)
plugged into the top of the chamber1. The chamber was ppen^ at the
bottom and weighted so that it \settled into the sediment and
effectively isolate a unit bottom area and a parcel of overlying
water. The stirrer provided gentle agitation to keep watetf
moving past the membrane on the\probe without stirring up the
sediment. The dissolved oxygen concentration of the trapped
water parcel was monitored for a sufficient length of tinte tc-
obtain a dissolved oxygen versus time slope (m). ^,The bottom
oxygen demand was calculated according to the following formula:
. mg oxygen ,.
m ^ L hr '
~nn gm oxygen , i 0/
SOD ฐ / J " = p! H 24
n> ' day .Q2 '
i
where H is the mean depth of the chamber in cm allowing for the
volume displaced by the stirrer. '
13
-------
SECTION 2.1.3 STATISTICAL METHODS
Statistical methods used consisted of 1) means and other
descriptive statistics, ;2) correlation analysis, 3) analysis of
variance, and 4) Duncan's Multiple Range Test (Sokal and Rohlf,
1969). A brief description of Duncan's Multiple Range Test
follows for readers not familar with the analysis.
Duncan's Multiple Range Test was Used to calculate means for
each variable (in this case specific nutrient parameters) by
station. The group means for each variable are then arranged in
order from largest to smallest. The test is performed for each
variable using tbe error)mean square, error degrees of freedom
ancl the F-value specified (a=0.05 unless otherwise specified in
this report). If one ofi the station variables is missing,' then
the observations at all! stations at that time are deleted from
the analysis. Means that are not significantly different from one
another can then be grouped.
Notably, this is a crude test; it does not have provisions
for time series analysis!, although most intercompared samples
were collected within 30 minutes of one another during the
Intensive Surveys and within 2 hours during. HWS surveys.
Secondly, some nutrientj concentrations fall below laboratory
analytical detection limits. In such cases, a value that is half
the detection limit was used for calculating means, since it was
felt that this value would be more representative than either the
lowest standard value or a zero value.
14
-------
2,1.A QUALITY CONTROL DATA
During the 1980 and 1981 intensive Surveys, 5 replicate
samples were collected simultaneously at several stations in the
estuary for each parameter. The mean, standard deviation and
variance were calculated arid results are presented in Table ^1.
Results showed good pverall quality control; standard
deviation and variance were very low. It should be noted,
however, that alkalinity, suspended solids and chlorophyll-a
measurements, in some cases, differed by one standard deviation
unit.
15
-------
JEable 1, Quality Control Infppnation.
VARIAUE
KAN
H.VIA1ION
VARIANCE
VARIABLE
SAL
to
SS
MP51
CHI Oft
PWO
Sli.'CA
SAL
DO;
ss;
MK.I
CHI OR
PMfO
SILICA
j
SIAtIOK=M|iSt
VAKUMi
SAL
HI
iiflnsi
tW.Off
(MEO i
SILICA 1
i 1
SAL '?
M \
SS
con:, i
CHI OK
PHtO
SltlW
Sfit
SS
MUSI
fHLOR
I-HEO
Sit IDA
KAN
16.84
5.77
16.20
1.42
8.04
5.56
2.66
18.48
6.53
9,00
1.35
8.52
2.92
2.33
HE AN
21.30
U.60
O.'?0
1.12
0.14
21.94
9.50
I7.?0
1.32
1.22
1.0?
Oils
,
22.70
9.82
3.10
1.59
1,44
0.42
oao
f
SIAWWRD
DEVIATION
0.09
0.08
3.42
0.24
0.40
0.44
0.05
0.04
0.29
4.24
0.24
1.18
0.37
0.01
STMMftD
DEVIATION
0.00
0.16
o!25
0.35
0.08
i
0.36
0.06
7.97
0.11
0.22
0.19
0.03
\
0.00
0.08
2.83
0.24
0.2;
0.04
0.01
VARIANCE
. 0.01
0.01
11.70
0.04
0.36
0.20
0,00
0.00
0.08
18.00
0.06
t.40
0.14
0.00
VARIANCE'
0.00
0.02
w?
0.07
0.12
0.01
0.13
0.00
63.45
0.01
0.05
O.C4
0.00
0.00
0.01
8.30
0.06
O.C4
0.00
0.00
STAflONstfRl
' Ptt
ALK
Off
TUN
mi
NH3F
N02
N02N03
Ptt
SIAIIOปปซ1 *LJ
' Off
i IP
UN
NH3
KHjf
NO:
1 N02NU3
i SIATiaN^Kl
VARIADLE
PH
ALK
OPf
IP
UN
IK*
HH1F
NO? ,
N02N03
SIAUON^HFHl
PM
M.K
OPf
IP
UN
MH3F
NO'.
NO., .03
SlATIQlWn "
PH
AlK
OPF
IP
IM
IKNF
NH3F
W2
N02N03
' 7.52
84.00
0.0]
0.10
0.71
0.00
0.00
9.00
0.00
7.64
78.60
0.00
0.05
0.59
0.00
0.00
0.00
0.00
KAN1
7.70
87.72
0.00
0.04
0.43
0.33
0.03
0.00
0.04
7.84
68.72
0.00,
0.04
0.39
0.30
0.01
0.00
0.02
/
i
7.91
89.38
0.00
0,02
0,34
0.29
0.02
0.00
0.00
0.02
0.23
0.01
0.01
0.04
0.00
0.01
0.00
0.00
0.12
1.47
0.01
OJOO
0.02
0.00
0.00
0.00
0.00
5IANDARO
DEVIATION
0.06
0.89
0.00
0.02
0.02
0.03
0.00
0.00
0.01
0.01
1.15
0.00
0.02
O.C1
0.02
0.01
0.00
0.00
0.03
1.01
0.00
O.*03
0.05
0.00
0.00
0.00
0.04
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0,01
2.16
0.00
0.00
0.00
0.00
0.00
0.00
4.00
VARIANCE
0.00
0.79
0.00
0.00
0.00
0.00
0.00
0.00
0.00
o.oo
1.33
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
1.03
0.00
0.00
0.00
0.00
0.00
0.00
0.00
l-t
VO
00
o
VO
00
t
* Sample size (q) = 5 in all cases above.
16
-------
2.2.1 1979 INTENSIVE SURVEY
On August 14 and 15,, 1979 an intensive survey was conducted
on the Ware River to provide a comprehensive picture of how
water quality changes temporally and spatially in response to
sunlight and tidal oscillation. Seventeen stations in the
estuary, four freshwater stream sites and the Gloucester sewage
treatment plant, the single point-source discharge into the
estuary, were monitored round-the-clock for slightly over two
cycles (27 hours). ;
Temperature, salinity and dissolved oxygen were measured
hourly, while samples for nutrients, chlorophyll-a, pH,
alkalinity, carbonaceous 5-day biochemical oxygen demand (BOD)
and suspended solids were collected every 3 hours. A set of
ultimate oxygen demand determinations was made once at HWS
throughout the estuary. Ancillary studies such as enumeration
of nitrifying bacteria, sediment oxygen demand measurements,
plankton biomass determinations and identification of major
phytoplanktpn groups were conducted as well.
Two tide gages arid 7 current meters were deployed to provide
hydrographicI information. Cross-channel bathymetries also were
taken along each station transect.
Water temperatures during the survey ranged from 25.4 C to
29 C. Similarly pH was homogeneous throughout the estuary ranging
from 7.3 - 7,9. Skies were clear on the 14th, air temperatures
ranged from 20 - 29 C (68 - 84 F) a^.d winds were out of the west
16 r 32 km/hr (10 -20 mph). On the 15th the skies were
overcast, air temperatures ranged from 20 - 25 C (68 - 77 F) ,
winds were calm, out of the north at 5 km/hr (3 mph).
Salinity
The Ware River is a mesohaline estuary and subject to
freshwater flow fluctuations. During the first intensive, a
relatively "wet" year, salinities ranged from about 17 ppt at the
river mouth to 10 ppt at Warehouse Landing, the confluence of
Beaverdam Swamp and Fox 'Mill Run. Temporal variation of
salinity showed a strong tidal periodicity, with greatest
variation upstream (see Figure 3). Amplitude of tidal variation
in salinity increased with'distance from the river mouth, with
range of variation reaching as high as 6.6 ppt at the upstream
stations. The longitudinal salinity gradient in the downstream
portion of the estuary was {slight, less than 0.12 ppt per km at
the mouth and about 0.5 ppt per km in the mid-reach of the
estuary. At the lan'dihg the jgradient was very large at low water
slack, on the order :c/f 3 or more ppt per km.
17
-------
18-
16-
14-
"ct
ฃ 12-
H 10-
z
Ij 8-
tn
o
4-
2-
o-
o<
^
O
LJ
1
Q 0 OO O
o
o o
o
> 0
3C
!
1 ,1 1 1 1
Q _
-------
The 27 hour intensive survey was conducted at a time of
neaptides, a period ,of maximum water column stability (Haas,
1977). Significant stratification, defined as a salinity
difference greater than 1 ppt between top and bottom stations,
occurred only at the two most downstream stations, Wl and W2,
and only during parts of-the tidal cycle (Table 2). This
indicates that tidal mixing dominates and that the estuary is
essentially well-mixed, especially in the upstream reaches
(Cameron and Pritchard, 19^5). The lack of stratification of the
water column at t-his time1 is probably due to 1) the shallow
nature of the estuary, 2) the proximity of sampling to the spring
tide turnover and 3) the westerly winds which would tend to
further mix the water column.
u
ssolved Oxygen
Temporal variations in dissolved oxygen were greatest at the
upstream (brackish) stations where concentrations ranged between
4'.5 |and 10.2$ mg/1. Oxygen concentrations were highest in mid-
afternoon and lowest just prior to sunrise. Due to the clear
weather and the fact that summer days are longer than nights,
oxygen concentrations near the surface exceeded saturation
values, as the plankton and benthic communities typically
produced more oxygen than they consumed. The maximum saturation
value (128%) was recorded of WFMl at 1414 hours.
' 1 ' ' ''
Durirtg thfe 27 hour sampling period, all of the estuarine
stations 'had mean oxygen values greater than 4.0 mg/1. Lowest
values were found in the deepest waters (/7 m) which might be
attributed to sediment oxygen demand; sediment oxygen demand
measurements taken .it the mouth one week prior to the Intensive
Survey; indicated a benthal uptake of 1.4 /gm/m2/day, or slightly
greater than the normal .demand present in estuaries of 1
gm/m2/day (Edwards, 1965)1
Chlorophyll-a
In this study chlorophyll-a was utilized as a measure of
suspended plant biomass. Values were within the range normally
found in estuarine waters and considerably below values
associated with nutrient enriched conditions. The highest values
recorded (16 ug/1) were for^a station at the mouth of the estuary
(wiT). Ghlorophyll-a values also tended to be elevated at the
upstream sites (W5). Temporal variations were observed
throughput the estuary. oiel variations were greatest' at the
mouth with values ranging from 16 to 1.9 ug/1. Throughout the
estuary, daytime values w^re roughly twice nighttime values;
diurnal variations appeared to be correlated more with sunlight
t:han tidal stage. This is perhaps another indication that the
Ware is relatively clean, since instances where chlorophyll-a
levels do vary significantly wit:h tidal xstage appear to ocur
mostly in highly enriched estuaries (Welch and Isaac, 1967;
Rosehb^um and Neilson 1977).
19
-------
tABLE 2. Salinity Differences between surface
and bottom samples during Intensive Survey
of the '^are River, August 11-15, 1979
hour
0900
1000
1100
1200
1300
1400
1500
1600
1700
1800
1900
2000
2100
2200
2300
0000
0100
0200
0300
0400
0500
0600
0700
0800
0900
1000
1100
LWS
HWS
|:
LWS
HVJS
LWS
E
n
"X
std. dev.
var .
W3
AS
(ppt)
0.18
rO.Ol
-0.02
-0.03
-0.01
-0.17
-0.14
0.01
olo
0.09
0*32
0.31
6.48
0.34
0.97
1.36*
6.82
0.20
-0.03
0.88
--0.03
-0.07
0.17
-0.01
-0.03
6.68
25
.27
.36
.13
W2
AS
(ppt)
0.14
-0.02
0.03
-0.03
0.01
0.04
0.04
0.01
-O.05
0.21
-1.31*
-1.41*
-0.06
-0.88
0.82
1.70*
O.Oi
1.31*
1.52*
0.40
1.40*
1.40*
-0.68
-OJ37
1.45*
-0.08
-0.42
AS
1.05*
.57
-1.04*
1.51*
0.06
0.00
0.95
1.32*
0.74
1.39*
0.16
0.04
0.18
1.77*
1.63*
1.44*
-0.23
0.49
1.52*
0.02
0.90
1.62*
1.16*
1.18*
1.75*
0.04
1.26*
15.50
27
.57
.62
.37
24.02
27
.89
.62
.37
* Times of water column stratification
20
-------
Since there was no mono ton i: longitudinal trend pฃ
chlorophyll-a concentration, this suggests that there might be
separate pools of phytoplankton within the estuary.
Physical/chemical conditions Such as light and temperature are
fairly uniform throughout the estuary. Therefore, the patchy
distribution of phytoplankton is probably due to salinity
gradients, advective effects of wind or water transport, nutrient
availability as in proximity to the marsh area, or to population
differences such as growth, moiruality, sinking and migration
rates of individual plankters and their grazers.
Nutrient and Suspended Solids Data
\ i
Temporal variations in nutrient concentrations were seen in
the brackish region of the estuary within a tidal period ,(
Maximum values for total Kjeldahl nitrogen, ammonia nitrogfen, and
total phosphorus occurred at times of low water slack) minimum
values occurred at high water slack (Figures 4-6). However^
nutrient water quality at the mout-h fluctuated, little with the
tides. Nitrite+nitrate nitrogen concentrations Were generally
below detection limit throughout the estuary during the survey;
71% of the samples were less than Q.05 mg/1. t As a result,
detection limits were lowered to ( 0.01 mg/1 to provide more
information, since this nutrient is important in /elation to
phytoplankton growth. |
Suspended solids (SS) showed no regular pattern through
27 hours, especially at the mouthi Overall, concentrations were
highest in bottom waters, which would be expected since sediments
will setttle from the surface waters and become moire concentrated
near the bottom. In the brackish region, increased solids
concentrations appeared to be, in part, . a function of incoming
Bay water (Figure 7), since denser, more salin^ bottom water
carries suspended particulates in a net upstream current
direction.
Lateral and Longitudinal Variations
The 1979 intensive survey was conducted not only to
determine diel influences in water quality but also to delineate
lateral and longitudinal variation^ t;hat mighft exist \.n the
estuary.
Five stations, WIN, W1S, W2N, W2S,. W3N, ( ske Appendix A-2
for station locations and descriptions) additional to the
slackwater stations were sampled in the estuary tP determine
whether cross-channel variations existed along a given transect.
Samples were taken at mid-depth, and v:ater quality parameters for
all stations located on a transect were compared. Results were
analyzed graphically and statistically > using Duncan's Multiple
Range Test to check for significant differences among' groups*
21
-------
ro
rs>
.20
9 10 11 12 13 14 15 16 1718 19 20 21 22 23 0 1 2 3 4 5 6 7 8 9 10 11 12
August 14 August 15
TIME (hours)
FIGURE 4. Average total Kjeldahl nitrogen concentrations in the brackish region (W5, WFMl, WBS1),
August 1979 Intensive Survey.
-------
r\>
1 TOTAL AfflQNfft
9 iO 11 12 13 14 15 16 1713 19 20 21 22 23 0 1
August 14
TIME (hours)
2 3 4 5 6 7 8 9 10 11 12
August lj>
1
.FIGURE 5. Average .total aramon-ia-riitrogen concentrations in the-brackish region (W5ป WFMl, WBS1),:
August 1979 Intensive Survey.
-------
1.50
r<
i
o
to
=1.00
o
x
-a.
CO
o
X
Q.
_J
<
-^05-
OrOO -
^
i \
TOTAL PHOSPHORUS
9 iO 11 12 13-14 15 16 1718 19 20 21 22 23 0- 1 2 3 A 5 6 7 8 9 10 11 12
August 14
TIME (hours)
August 15
FIGURES. Average-, total phosphorus concentrations in the'Brackish region <ป?v,.-WF!
and stream sites (STR3, STR4), August 1979 J-ntensive Survey-
-------
en
r-i
30 -
25,- .
C3
co 20
o
o
CO
Q 15-
LLJ
Q
to
Z3
CO
10 - r
5--'
-0 . .
SUSPENDED SOLIDS
9 iO 11 12 13 K 15 16 1718 19 20 21 22 23 0 1 2 3 4 5 6 7 8 9 10 11 12
August 14
TIME (hours)
August 15
FIGURE 7. Average suspended solids concentrations in the brackish region (W5, (WFM1, WBS1),
August 1979 Intensive Survey.
-------
Longitudinal variations
Significant differences were found in station means for
salinity which ranged from 17 ppt at the mouth to 10 ppt in the
brackish area (V?5, WBS1, WFM1). This salinity difference of 7
ppt was twice as large as the 3 ppt (averacs) longitudinal
variation found over the 27-month study. Hence, the survey
results can be used to delineate diel variations during a "wet"
year. Average temperatures were fairly homogeneous throughout
the main stem of the estuary during the study: at no time 'did
temperatures range more than 4 C between stations. No significant
longitudinal differences were found in levels for ammonia,
dissolved' ammonia, tbtal Kjeldahl nitrogen, inorganic nitrog.en
and organic riitrogen. Chlorophyll- a means varied by only 4.8
ug/1 dt a giveh hour, from a maximum of 9.9 upstream (WBS1) to
5.1 ug/;l near the mouth (W2). Significant differences, however,
were found ^.n total phosphorus and dissolved oxygen percent
saturation, Highest oxygen levels were found at W5 and lowest at
W1B; Concentrations of total phosphorus varied throughout the
estuary, with highest concentrations in the brackish regions
(W5, WBS1, &FM1) and lowest values downstream (W1S).
Lateral variations '. .
I ' '
Individual transects were analyzed for significant
differences between station means. Analyses were conducted both
with and without the bottom station in order to avoid skewing the
significane testing for certain parameters (e.g., dissolved
oxygen, salinity; total phosphorus) where large differences can
exist in 'the water column.
Results from the Duncan's Multiple Range Test indicated no
significant difference between sample means along any of the
transects for total Kjeldahl nitrogen, organic nitrogen and
ammonia nitrogen. Similarly, peKcent oxygen saturation was
homogenous along the first two downstream transects, Wl and W2.
Percent oxygen saturation was significantly different across
transect W3; the percent oxyyen saturation in the channel margins
averaged about 10% above that in the main stem and appeared to
vary with tidal stage (Figure 8). Likewise percent oxygen
saturation was significantly different (a=0.05) between top and
bottom station means at all transects.
Total phosphorus concentrations were predominantly below
detection limit in the downstreart waters (65% of the samples
were less than 0.05 mg/1) and thus not suitable for this test.
Of 143 measurable observations of ^23 samples, concentrations
were highet in the bottom waters.
r..
Differences in salinity amounted to less than 2 ppt among
the stations along a transect; This also tends to indicate that
stratification was riot present since top and bottom samples on a
given transect varied little.
26 i
-------
130f
i
'120
tr
CO
z
LU
e>
x
o
a
ro uj
."** >
CZ
LU
O^
50-
./
.W3N'
W3B
H - \
9 10
4
11
>\
12 13 14 15T.617 l'& ~I9 2a 21 22 23 00
August 14
TIME (hours)
August 15
ซ
i ^. .j~_...i | | t > t i I i | I *
223^00^ I T 3 4 i '& ?' 8 9* l6 ll
FIGURE 8... Tercent dissolved-oxygen-saturatlon at transect W3-, August 11J7S-Intensive Survey.
-------
Results from the lateral and longitudinal analyses tend to
indicate that the Ware River estuary is more homogeneous
laterally than longitudinally. Lateral differences were found
only along transect W3 and for only one parameter, dissolved
oxygen. Longitudinal gradients, however, were discerned for
salinity, totail phosphorus and dissolved oxygen. Vertical
differences were significant for dissolved oxygen, total
phosphorus and suspended solids. It is interesting to note that
in the Ware River, percent oxygen saturation was the only
parameter that varied significantly between stations in all
three directions (across the channel, along the channel and
vertically through the water column). It appears that oxygen
and salinity, relatively easy to measure parameters, may provide
the best, first-cut indication of the existence of density
stratification, as well as how this might affect water quality
in the estuary.
23
-------
-2.2,2 1980 Intensive Survey
6n July 9 and i<3, 1980, a second intensive survey was
conducted dn the Ware Riveir estuary. The survey was coordinated
with the 'Chesapeake Baywide Nutrient Survey and also was a
cooperative effort with Mr. Dale Phillips of the Virginia State
Water', Control Board and Mr. Wesley D. Jones, the Gloucester
County Engineer. Phillips was interested in calibrating and
evaluatirig(a stream transport model of Foxmill Run from above the
sewage treatment ' plant to the mouth of the Ware River estuary.
The 1980 Intensive Survey was conducted during a relatively
dry summer. Less than 2 inches of rain fell during the 30 day
period 'preceeding the survey. This was 2.3 inches below the
monthly mean rainfall recorded for that time period for the past
13 year& (National Weather Service, Bohannon, VA) . Freshwater
flow at the USGS gaging station ati Beaverdam Swamp, however,
averageij 7.6 cfs during the survey which is about normal, based
on the discharge recorded at the gage fot the past 30 yeai^s.
The higher-than-anticipated flow was probably due to 0.3 inches
of rfiin that fell in the watershed 2 days prior to the survey.
Weather conditions were somewhat similar to the first year's
survey. Estuarine water temperatures ranged from 25 to 30 C.
Skies were mostly clear on the 9th, air temperatures ranged from
72 to 86 F (22-30 C) and winds were out of the east, 3-11 mph.
toear midnight, squall warnings were issued and winds of up to 23
mph out of the northwest were reqprded fo several hours; only a
trace of precipitation was measured. On the 10th, the skies were
partly cloudy, air temperatures ranged from 74 to 88 F (23 r-31 C)
and winds were calm out of the southwest, 3-11 mph.
A total of 11 stations in the estuary, 6 fres-hwater stream
sites and the Gloucester sewage .treatment pla~nt, the ^single
point-source discharge into the estuary, were monitored around-
the-qlock for slightly over two tidal cycles (27 hours).
Temperature, salinity and dissolved oxygen were measured
hourly1 while .samples for nutrients, chlorophyll-a, pF,
alkalinity, carbonaceous biochemical oxygen demand and suspended
solids were collected ^very 3 hours. Additionally, the upstream
stations (W4, W5, WFM1, FM2, FM3, WBS1, BS6, BS8) were sampled
hourly for silica, .total phosphorus, nitrite^nitrogen and
nitrate-nitrogen. . A [set of ultimate biological oxygen demand
measurements, plankton biomass determinations and identification
of major phytoplankton 'groups were conducted as well. -
i
.29 - ' . r
-------
Two tide gages and 5 current meters were deployed in the;
estuary to provide hydrographic information duting the survey.
Longitudinal Differences
Mean oxygen concentrations (percent saturation) were highest
toward the river mouth (W2T) and lowest in the upstream brackish
regions. The point-source stream stations (FM2, FM3) had lower
oxygen values than the stations in the tributary which had only
nonpoint source inputs; The greatest variation in estuarine
oxygeh concentrations occurred in the brackish area. Values
ranged from 9.52 mg/1 (130.3% saturation) at.WBSl'to 3.24 rog/1
(38.9%) at FM2.
Average salinities at the mouth were 18.2 ppt. Station W5
averaged 17.1 ppt which is 2.5 ppt above the seasonal average and
4.3 ppjp above the 1979 Intensive Survey averages recprded at that
station. Salinities decreased rapidly with distance upstream,
reflecting an even stronger longitudinal salinity gradient in the
upper I', reaches of the estuary. For example, there was
approximately at 0.7 ppt per km change in salinity concentration
at1 low water slack between the mouth and the mid-reaches of the
estuary^ Near the landing (W5),i a gradient of 2.2 ppt per km
occurred. In the transition j zone 'e salinity gradients were very
large, on the; order of 17 ppt per km.
i LOW suspended solids concentrations were tound downstream
(10 mg/1); particulate matter was greatest in the brackish
regions just upstream from th'e landing (WFM1, 34.8 mg/1; WBS1,
32.9 mg/1). I ,
I /
I Dissolved silica exhibited a longitudinal gradient, wh: :h
would be expected from a ' somewhat conservative element.
Concentrations ranged from 8 mg/1 in the freshwater stream sites
to 2.3 m'g/i at the mouth of' the estuary. Brackish regions
contained an average of 4 mg/1 of silicate.
uissplved orthophosphorus1 was measurable only in Foxmill
Run, \pre'ฃumably due to effluent from the sewage treatment plant.
Concentrations were 6.8 mg/1> at the point of discharge and
decreased to 0.2 mg/1 in the upper brackish areas. At WFM1,
values ,were below detection 'limit, as was also the case
throughput the estuary.
Total phosphorus was excessive at the sewage treatment plant
outfall (9.8 mg/1) and appeared to decrease due primarily to
dilution in Foxmill Run (see Figure 9). However, concentrations
increased slightly at FM2. This may indicate an important area of
physical interactions in Foxmill Run (a turbidity maximum) since
suspended solids also increased and salinity concentrations
average 0.5 ppt.\. Phosphorus concentrations were moderate in the
brackish region and decreased longitudinally towards the mouth.
It should be noted that most of the phosphorus measured was not
in the orthophosphate form.
30 '
-------
mg/1
l .0 H
0 "3 J
0.4 -5
0. 3
3.: -
c ; -i
WARE RIVER jl 980 INTENSIVE
1
AVEKAUf fHOSl-HUROS CONCENTRATIONS
i
-.BC: 5C5
.-
'^ '.^ Ortho-P
Note : ST? values have been divided by 10
Figure 9. Phosphorus specie mean concentration, July 1980 Intensive Survey.
31
-------
Figure 9 and 10 are helpful illustrating the overall
contribution of nutrients to the estuary by the sewage treatment
plant. The majority of the measurable nitrogen, or approximately
50-100%, appeared to be organic in nature during- the survey.
Nitrate-nitrogen was more abundant than nitrite-nitrogen and may
indicate nitrification is occurring. Ammonia-nitrogen in Foxmill
Run had high levels recorded during the survey, comprising
approximately 40% of the measurable nitrogen. Highest ammonia
nitrogen values were recorded at the sewage treatment plant
outfall (4.2 mg/1); values downstream in Foxmij.1 Run were also
elevated (0.2 mg/1).
LOW total nitrogen to total phosphorus ratios by atomic
weight (TN:TP) , or periods, of. nitrogen-limiting conditions] were
observed during the survey (Figure ll). At the mouth and jnid-
reaches of the estuary, nitrogen-limiting conditions appeared ฃo
be the result of low inorganic-nitrogen levels. In th.e marsh
region, inorganic nitrogen level's were high; nitrate-nitrogen
comprised the greatest fraction of the inorganic nitrogen.
Maximum values of both inorganic nitrogen and total phosphorus
were recorded in Foxmill Run, which resulted in the lowest
recorded TN:TP ratios in the estuary.
/'
The TN:TP ratios both compare and contrast with the previous;
year's data. By contrast, the estuary was phosphorus-limited
during the summer months of 1979. However, the nitrogen
conditions present in Foxmill Run were consistent and even
expected based on the low ratios recorded at the freshwater
stream site (STR3) during the previous year. Presumably, such
low TN:TP values are attributable to the wastewater discharge,
since sewage is typically phosphorus rich.
Temporal and Diel Variations
Similar to the 1979 Intensive Survey, dissolved oxygen
displayed a distinct diel periodicity. Oxygen concentrations
were highest in mid-afternoon and lowest just prior to sunrise.
The brackish region of Beaverdam Swamp had' both the greatest
oxygen supersaturation values (136%) as well as the greatest
range in values recorded in the estuary '(48.6% - 136%) over a 24
hour period.
By extending the 1980 Intensive Survey upstream into \ the
tidal portions of the marsh, several interesting new patterns
emerged. This time, highest chlorophyll-a values recorded in the
estuary were at FM2 (37.1 ug/1), more than twice the value? found
in the estuary during the 1979 Intensive Survey.
At the mouth of the estuary, values averaged 10 ug/1 and
exhibited diurnal variations that appeared to correlate with
sunlight rather than tidal stage. However, in the narrower
upstream stretches of the marsh, diel patterns correlated moire
strongly with stage of tide than sunlight. A compa,ri$on of
chlorophyll-a levels at FM3 and FH2 tends support the notion that
phytoplankton populations increased during high tide (Figure
32
-------
mg/1
WARE PIVER 1980 INTENSIVE
AVERAGE NITROGEN CONCENTRATIONS
STR' J01
5S5 BS5 STR4
Figure 10. Nitrogen species mean concentrations, July 1QR0 Intensive Survey.
33
!
-------
WARE RIVER 1980 INTENSIVE
9 -
9 -
3 -|
1 -I
'
g
/<;.-/
1
m
'
'
'.'/
&/.,
.'A
n/.'
m
H
i
i>
/'
m
ง
^
UK3
5S5 BS9 i
' ICN
Figure. 11, Average t;i:TP ratios, July 1980 Intcnoivo Survey.
-------
12a), since neither salinity nor chlorophyll-a levels fluctuated
at FM3 (at the head of tide region), but did so at FM2. In
Beaverdam Swamp, conversely, elevated chlorophyll-a
concentrations occurred during LWS, implying . nonpoint source
nutrient inputs from the marsh may be an important factor (Figure
12b) .
Salinity concentrations were similar at STR3, STR4, and FM3,
or roughly 0.2 ppt. Chlorophyll-a Values were consistently low*
and homogeneous there, or less than 2 ug/1. At FM2, salinity
gradients greater than 0.!? ppt occurred during HWS only. During
these periods, significantly higher measurements of a
chlorophyll-a were observed. Such increases , in prijnary
productivity tend to support the idea of a turbidity maximum at
the freshwater/saltwater interface.
35
-------
us/1
36.0 -
33.0 -
0.0
WARE RIVER 1980 INTENSIVE
;
CHIOROPHYU A
July 9
July 10-
T I M E
Figure 12a. CHlorophyll-a concentrations at FM2 and FM3, July 1980
Intensive Survey.
36
-------
ug/1
36.0 -
12.0 -
9.0 H
6.0 -i
3.0 -
0.0 -
WARE RIVER WBO INTENSIVE
CHIOROPHYU A
1200 ' 1800 0000
0600
-ju}y 9 -ซ July 10-
T I M E
Figure 12b. Chlorophyll-a concentrations at BS6 and BS8, July 1980
Intensive Survey*
37
-------
2.2.3 1981 INTENSIVE SURVEY March 25-26, 1981
One of the most dramatic anhual phenomena observed in the
Ware River estuary was the chloro,phyll-a maximum that occurred
each spring in 1979-1980. After collecting two complete data sets'
of diel fluctuations during consecutive summers (August 1979 and
July 1980 Intensives); a spring intensive survey was planned for
1981. ' '" ' "\ ' '
The purpose of sampling in the spring was toN capture the
diel nutrient dynamics surrounding the chlorophyll-a maximum.
The survey, conducted March 25-26, was designed to complement the
ongoing Spring Survey of 1981 (see Section 2;4). Thirteen
stations in the estuary, 7 freshwater stream sites and the
Gloucester sewage treatment plant were monitored round-the-clock
for 2 tidal cycles. Two of the estuarine stations (Pig Hill and
Goshen) were sampled using automatic samplers. /
In the estuary, grab samples were collected ev,ery three
hours; the automatic samplers were set for hourly' sampling.
Temperature, pH, alkalinity, salinity, dissolved oxygen,
chlorophyll-a, silicates, suspended solids, Srday carbonaceous
biochemical oxygen demand and nutrient samples were colle9ted.
Water temperatures during the survey ranged from 6.5 to }0.5
C. Weather conditions were "seasonable" during 'the survey.
Ambient temperatures ranged from 29 to 53 F (-rl to 11 C) . On
March 25th, winds were moderate and out of the north (5 - 1.6
mph), but shifted to a southerly flow by the next day
mph). No precipitation was recorded over the 24 hour
previous rain had fallen on March 23 (0.39 in).
Longitudinal Differences
(5 - 21
period;
Average salinities at the mouth |W1) were 23.3 ppt; nine km
upstream, at Warehouse Landing (W5), values declined slightly, to
22.6 ppt (Figure 13a), which was 5.5 ppt greater than during the
previous intensive, and emphasizes the paucity of spring runoff.
As in -che 1980 survey, a strong longitudinal salinity gradient
was present in the upper reaches of the estuary: at LWS Salinity
varied 20 ppt between WFM1 and FM2 reflecting a longitudinal
gradient of 6.3 ppt per km. Similarly, in Beaverdam Swamp,
salinity changed 4 ppt per km between ^JBSl and BS8. Downstream
gradients were indiscernable; at. LWS there was 0 ppt change in
the first 4 kilometers. /
values
were
Mean dissolved oxygen (percent saturation)
higher in the mouth of the estuary and irj the freshwater strpams,
and lowest in the brackish reaches. Supersaturated conditions
38
-------
.35-
AVWACC SALINITY CONCENTRATIONS
WARE R:VฃR SP'lNC INTENSIVC SOPVEY
SILICA
1981
vo
ppt
7 7
mnm
'$MMU
5 H
3 3
3 r
ft
M
'
mg/L
F i
!. -t
3
K K
: :
7 6
1
I
4 5
S S
T T
R P
3
B S
S 8
I
STU'ICN
Figure 13a. Average salinity concentations,
1981 Intensive Survey.
Figure 13b. Average dissolved silica concentrations,
1981 Intensive Survey.
-------
existed at.all stations downstream of Warehouse Landing. Highest
values as well as the greatest range were present at W1B, where
maximum chlorophyll-a values were also found. The point-source
tributary (Fox Mill Run) contained lowest mean values, but due to
the cool temperatures, saturation did not fall below 70%.
Silicates showed a strong longitudinal gradient during ;the
spring survey. A significant decrease in concentration between
stations WBS1 and BS8, and 'WFM1 and FM2 was- found, Which
paralleled , the limit of freshwater intrusion (Figure 13b).
Levels at the STP were similar to 1980 survey values (7.6 mg/1).
However average values in the main stem of the estuary were less
than 0.5 fpg/iป almost 2 mg/1 less than what was present .the
proceeding summer, which would be expected during reduced
baseflbw conditions.
i ' \" ' t'
Aside front the STP, chlorophyll-a values were highest at-the
mouth of the estuary (Figure 14). In general, mean values
decreased with rivermile, tending to confirm the subsurface
transport of phytoplankton as found in 1979. Concentrations were
extremely low, however; maximum values in the estuary (W1B) were
2.5 ug/1.
As ekpected STR3 had the highest BOD values (5.7 mg/1). One
kilometer downstream, levels dropped rapidly and the remainder of
the stations sampled were not significantly different, averaging
less than 2.0 mg/1 (Figurซ; 15). 1
Suspended solids were highest in the brackish region of the
marsh and were lowest in the surface waters at the mouth (W1T=1.8
mg/1). Values also decreased upstream of WBS1 and WFM1 (Figure
16).'
Filterable ortKophosphates were measurable downstream of
the point-source in Foxmill Run only (Figure 17). Concentrations
returned to baseline (as observed ufpstream of the STP at STR10)
at WFM1 of 0.01 mg/1. Concentrations were uniformly undetectable
in the main stem of the estuary. The NFS freshwater tributary
(STR4) contained little orthophosphates whereas orthophosphorus
predominated in the point-source tributary.
I
Tot-xl phosphorus was high at the sewage treatment plant (6.5
mg/1) and decreased with distance downstream (Figure 17). . At
station VTFM1, background levels (as measured at STR 10) had
returned to p.03 mg/1. Concentrations were above detection
limits (0.01 mg/1) at all stations, however, no longitudinal
trend was observed, ;.
i * -
Extremely high concentrations of total Kjeldahl nitrogen
were measured at the STP j[!R=30.3 mg/1). Slightly less than half
of the total Kjeldahl nitrogen was in the dissolved form (13.7
mg/1). At all other stations, dissolved tccal Kjeldahl nitrogen
represented at least 75% f the measurable fraction (Figure 18).
Nitrite-nitrogen was not^measurable in the estuary except at STP
and FM2. Nitrate-nitrogen was slightly more prevalent but was
40 ''.'
-------
WARE: RIVER SPRING INTENSIVE SURVE-. 1931
CHLOROPHYLL A
M 2 R P K 5 8
M"
Figure 14. Average Chlorophyll-a concentrations, 1981 Intensive
Survey.
41
-------
rag/1
WARE RIVER SPRING INTENSIVE SURVEY 198'.
CARBONACEOUS BIOCHEMICAL OXYGEN DEMAND
.
3 T)
}
i
H
2 -
p
/
V
y
i
Kh'KKKUKFS
5 K
T B
Figure 15, Ayerage carbonaceous biochemical oxygen demand, 1981
^ Intensive Survey. '
i ' '
42
-------
WARE RiYER SPRING INTENSIVE SURVEY 1981
10TAL hLTERABLE SOLIDS
mg/1
20 -
,8-
16 -
14 -
12 -
1C -
6 -
5 -
4 -
B
'3
X
/
งE
/ '
. o nfififyflr
r^i ^n t/ ^ X ^ ^ /
K K K h K K W M
1 1 3 3 k 4 5 F
T B T B C r
2 1
i ^
8
40j
F S
f1 T
2 R
3
^
^
/
^
/
X
^
/
/
<
S
T
F
n
s
T
R
1
r-
i
$
j
ii
/ f\ ^
/> \S\ __. V;
K 5 'S S
B ฃ ..T 1
5 6 :R ?
V4 9
STfl^lON
/ ]
Figure 16. Average total filterable solids, 1981 Intensive
Survey. .;
43
-------
WARE RIVER SPRING 1981
AVERซGC PHOSPHORJS CONCENTRATIONS
mg/1
C.6 -
0.0 -1
0.4 -1
0.
i
IZL
ortho-P
REPULSE'.'; 'C;AL
.E 3ฃE\- DIV.DLD er ^
Figure 17. phn<,nhr,rilR
Survey.
mpan roncentrfltlons, 1981 Intensive
44
-------
mg/1
i .<
r 3
WARE RIVER SPRING INTNSiVE 1981
AVERAGE FITERABLE NITROGEN CONCENTRATIONS
l
-NO 3
NCC
Figure 18. Nitrogen specie.1? mean concentrations, 1981 Intensive
Survey.
-------
measurable only upstream of station W5. Ammonia-nitrogen values
similarly exhibited a longitudinal gradient. Values were below
detection limit downstream of W5; values were high at the STP (12
mg/1) and returned to baseline by WFMl.
Interestingly enough, WBS1 contained higher mean values for
inorganic nitrogen than WFM1, the point source tributary. Most
of the contribution was in the ammonia-nitrogen form, and
indicates the importance of noripoint source contributions from
the marsh in this region.
Nitrogen limiting conditions were present at the STP and in
Fox Mill Run. All othej: stations, including freshwater
tributaries, had high ratio values (Figure 19a) indicating
phosphorus limiting conditions. The same pattern was observed in
1979, which would be expected since Chesapeake Bay is generally
considered to be a phosphorus limited estuary, and sewage is
typically, phosphorus rich. \
i
Values .for dissolved inorganip hitrogemorthophosphprus
were calcuable in Fox Mill Run and WBS1 only (Figure 19b) . y\t
the other stations, orthophosphorus was too low to use in
calculations.
I i /
There was no longitudinal gradient for total organic carbort
concentrations in the estuary (Figure 20). 'Stations ' were not
significantly different from each other and averaged 4.0 mg/1.
Values at the sewage treatment plant were high (128.7 mg/lj<
Temporal and Diel Variations
Similar to the two proceeding intensive surveys^ dissolved
oxygen showed a distinct aiel periodicity. Times fof iriaximum
oxygen concentrations occurred in th'e late afteirnopn (1830
hours); lowest values occurred just'prior to suhris'e (0430
hours).
Silicates exhibited a tidaliy related pattern in the
brackish area: high values were associated With LWS. Temporal
variations in several other nutrient concentrations were also
most evident in the brackish region. Maximum values fpr total
Kjeldahl nitrogen, ammonia-nitrogeni total organic carbon and
total phosphorus occurred at times of low water slack; minimum
values were present at high water slack; Station WIT was , the
only exception: higher total Kjeldahl nitrogen values were
present at HWS. '
Chlorophyll-a and biochemical oxygen demand showed /io
temporal or diel variation in the estuary. This was probably .due
to the fact that overall values were quite low at; this/time of
year. ' '
! \ |
Suspended .solids were similarly low during the spring
intensive, especially downstream. Stations in the brackish ar^a
(WBS1, W5, Pig Hill and Goshen), however\ demonstrated a tidal
46
-------
WARE RIVER SPRING INTENSIVE SURVEY 1981
TN : TP (ATOMIC WEIGHT)
so
-id -
30
/
X
X
X
>
"a
X
x
>
/
/
w
1
ll
X
X
li ^i
/.
m
w
w
3
B
: F r
f. 2
1
STRT!OH
S S K
T T B
F R ฃ
1 1
C
B
S
a
s s
T T
R R
4 9
H.r'GMT RE?=?E:SE:\TS :^HCUR AVERAGE VALUE
Figure 19ai, Average TN:TP ratios, 1981 Intensive Survey.
47
-------
WARE RIVER SPRING INTENSIVE SURVEY 1981
DIN : P04 (ATOMIC WEIGHT)
9 -
8 -
n _
6 -
5 -
4 r.
'
3 -
.** -
1 -j
-
3
M
K V. k K K K W U
( 3 3 W 4 S F
T B T 6 C *
ฃ i
^
^
^
^^
^
^
!
2
F
M
2
ฃ
/
^
^
/
|
^
^
S
T
R
3
/
/
f
f
'
S
\
f
S
T
F
'
A
S H S S &
T B S 1 T
R S 8 R R
11 49
0
ETfi'iO..
Figure 19b. Average D1N:PO, ratios, 1981 Intensive Survey.
48
-------
WARฃ SlVtP SPRING INTCNSiVC SURVEY 198* .
TOTAL QRGANIC CARBON MC/L
3AR -:L:-:-"
Figure 20. Average TOG concentrations, 1981 Intensive Survey.
49
-------
relationship: highest concentrations occured during LWS, low
values were present at HWS. .
50
-------
2,3 TREND ANALYSES: April 1979 - July 1981
In order to determine the natural variations in nutrients
and related elements in a system that is not overenriched, a"
water quality sampling program was initiated on the Ware River.
estuary in April 1979. Semi-monthly highwater slack surveys were'
conducted during the first year; monthly slack surveys with more
upstream (tidal marsh) stations were implemented in the second
year* (See Appendix A for a list of sampling dates and times and;
other information,) Seasonal means, standard deviation and
variance were calculated for each station. Seasons were defined.
* i
as: :
Season Month Water Temp. ';.'
Spring April, May, June 10 - 20 C "
Summer July, August, September 20 - 30 C
Fall October, November, December 25 - 10 C
Winter January, February, March < 10 C
Results (Were plotted against time to concatenate seasonal
trends. Salient findings from the seasonal slackwater data
follows. Note: no appreciable longitudinal temperature variation
was found between stations in the main stem of the estuary during
the 27 month study;
Chlorophyll-ra ':
Chlorophyll-a exhibited a distinct spring peak in 1979 and
1980 in the main stem of the estuary (Figure 21), coincident with
rapid temperature rises' in the estuary (Figure 22). Chlorophyll-;
a values of 25-35 ug/1 were observed which is several times the
annual average of 9.5 ug/1. Greatest concentrations at this
time were found irt the bottom waters at the mouth and this may
reflect an annual long-range subsurface transport phenomenon of
plankton as observed in Chesapeake Bay for Prorocentrum mariae-,
leboriae (Tyler and Seliger, 1978). Theapparent spring
subsurface.chlorophyll maxima in the Ware River was followed by a
surface bloom; chlorophyll}-a values at the mouth decreased
thereafter with depth until fall. In addition to the spring;
blooms, a secondary summer pulse (12-15 ug/1) was observed in the1
brackish waters, illustrating the patchy and ephemeral nature of
plankton populations. -..
\ ' i _ ':
\ Phytoplankton enumerations into major groups were made
seasonally at several statio'ns throughout the estuary to augment
chlorophyll-a data. Cell 'counts showed diatoms to be the
dominant organism in the downstream stations throughout the year...
51
-------
CHLOROPHYLL CONCENTRATION
(UG/L)
ro
4
i
1
1
j
* r
A 7!
/ i /"!
;o.r. -J
/1 / i
i ' I : 1 i
V,
u -V /
i M
S t
F M A M. J J
-1981
Figure^21_. Time-series-plot of chloroehylT-a coneentrations, Stations WLT, WBS1", STR4.
-------
: -- CELSIUS
4
j
j
'ฐ-1
j
1.2
f ;
V?
'
?
f,U
*> i^
k
R
fi:<
f'
:
,
,
>
t
t-l
A M J J A S N J. F M A M J A S N. D J
1979,
1980
M AM J J
1981
..I'M ,:; WlB :-.---:-: WBS1
Figure 22. Time series plot of temperature, Stations WlB and WRS1,
53
-------
The classical spring chlorophyll-a peak in 1980 contained mostly
diatoms, primarily Rhizosoleriia and Nitzchia. Diatoms continued
to dominate throughout the year, however cell counts were I6w in
summer. The downstream spring peak was followed by an upstream
period of dinoflagellate dominance. Times of dinoflagellate
blooms were associated with high chlorophyll-a values and low
nitrite-nitrate nitrogen concentrations, since nitrite-nitrogen
usually is an important source of nitrogen and is assimilated
rapidly by the bloom organisms. This pattern has been observed
previously in the Rhode River (Seliger, 1972). Green flagellates
increased in number during the summer months and by fall diatoms
were present in the brackish region. In the middle reaches of
the estuary, phytoplankton populations appeared to reflect: an
intermediate assemblage; diatoms predominated throughout the year
except during the summer, wh^n green flagellates were most
numerousi
i .
Biochemical Oxygen Demand -
Nitrogen-inhibited carbonaceous biochemical oxygen demand
measures the amount of oxygen required by microrganisms to
decompose aerbbically the carbonaceous fraction of organic matter
present in a water sample. Total biochemical oxygen demand is a
measure of the oxygen needed to decompose carbonaceous as well as
nitrogenous fractions of organic matter. As expected, total. BOD
exerted ajslightly higher demand than carbonaceous BOD, although
the two were highly correlated (r=.9C, n=676). !
Both parameters showed much the same pattern as chlorophyll-
a throughout the Study period and, in fact, correlated slightly
(r=.72, n=624 for BODS; r=.69, n=888 for BOD5I). Highest BOD
values occurred in t-.he freshwater streams and tidal tributaries
(STR6, STR3, FM2) . Highest estuarine oxygen demandi was found
during the spring in the bottom waters near the mouth (W1B), Peaks
were observe'-! throughout the estuary in the summer and fall> as
well (Figure 23). ' Measurements ajpove 5 mg/1 are considered by
some to be indicative of slightly polluted waters (Ott, 1978);
this occurred 37 times in the Ware River out of 931 stations
sampled. Values never rose above 8.0 mg/1.
Nutrients
Nutrient concentrations are generally low in the Ware Rivr
estuary especially when compared to the freshwater tributaries or
to larger, more urbanized systems. At no season or station were
anoxic conditions encountered in the estuary. However, there was
a distinct longitudinal gradient piresent in the estuary: percent
saturation of dissolved oxygen was significantly higher at the
mouth thar. in the upstream reached. The study average showed 90%
oxygen saturation present at W1B; WBS1 had only 70%. Lowest, and
highest values were four>d during the summer months (Figure 24),
due to large diurnal fluctuations caused by photosynthesis and
respiration. ! '.
54 '
-------
BiOLOGiCAL OXYGEN DEMAND
NITROGEN INHIBITED (MG/L)
Ul
en
a
i \
: i
I \
K : I-
:.05 J
C SC-
i.
<
/'A
\\
\y
V
V
-A- M J J A S 0- N D J F M A ~M J J
1979 1980
S 0 N D- J T M :A- M J J
1981
LfSf'I::-. MS' I'J'I
Figure 23. Time-series plot of carbonaceouss-biochemical .oxygen-demand, Stations Wit and WBSI,
-------
DISSOLVED OXYGEN
PeRCE-NT-SATURATION
U1
Ol
i (
4
i !!
' * / !
1 A * M
* ! I
i ' i /\ / ,
H l- Ml /
3 ( i //\\ 1 J;
i * i ?/ * rป.
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3 ' : ' 'Jj I ;
5 ;| *- ! i | !
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J * < : i ; l
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1 M ' I i
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1 : :'
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< 't
: ii
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M A , ^ /' _--' /. \
> "1 ^^r \i i \ / \ / ? /,
' f Ml / \ / \ ' ^ ' s
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' ' / Hป M / v- / / ^
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r '' ;. x
/ i! i
;'V' ! /
1 -* ?> l /
'*; i /
;; j ;
li
i *
! '
" '
$ if
AMJJASONDJ. FM AM JJASONDJFMAM JJ
1979 1980 1981
LfCfNC: W1B ~
Figure 24. Time-series plot of dissolved oxygerr percent saturation at W1B and WBS-1-.
-------
Tota'l phosphorus (TP) and dissolved orthophosphorus (OP)
showed maximum values during the summer months and declined in
the winter , Highest concentrations were found in Fox Mill Run.
In the marsh region, total phosphorus values were generally
indicative of normal enrichment levels, however during the low
flow months (July and August) of the study, concentrations
averaged >0.13 mg/1, which has been considered a high level of
enrichment (Neilson, 1980; Ketchum, 1969) (Figure 25).
Downstream station averages were highest in the summer" as well
(.02 "t^i im9/l)f with bottom waters containing greater
concentration? than surface waters. Downstream values, were
moderate throughout the rest of the year.
Sili'catos were measured biweekly beginning in September,
197!j), ! therefore only 23 months of data will be presented.
Highest concentrations were found in the freshwater streams and
values generally decreased with distance toward the Bay. Silica
is .considered to be a semi-conservative nutrient and there was a
weak, negative correlation with salinity (r= -0.64? ri=744).
Distinct' seasonal patterns were observed: peak values for
silicates in estuary were recorded in the summer months; low
concentrations were seen in the winter until early spring (see
Figure 26). Freshwater streams and tidal tributaries registered
highest values in the summer and fall months} -lowest
concentrations were present in the winter and spring. Increased
concentrations from baseflow or runoff must account for elevated
summer levels. Freshwater dilution, and diatom uptake may
explain1 the lower concentrations present in the estuary during
the winter and spring.
Organic nitrogen values consistently comprised the largest
fraction of the total measurable nitrogen in the Ware River.*
Highest values for organic nitrogen and ammonia-nitrogen (thus,
t)ie highest total Kjedahl nitrogen values) occurred in the
summer; at that time amounts of organic nitrogen greater than 1.1
mg/1 were recorded at several places in the estuary during each
slackwater survey. Higher concentrations of organic nitrogen
were present in the estuary than in the freshwater streams and
largest overall concentrations were found at BS6 in the brackish
area proximal to the turbidity maximum.
fhe seasonal pattern for nitrite+nitrate nitrogen levels in
the Ware River estuary showed highest values to occur in November
through April, or during cold temperature and high flow
conditions, and decline during the sunmer months (Figue 27a-b).
The seasonal fluctuation was most likely attributable to
increased nitrate following the fall crop harvest, enriching the
ground water recharged by the fall rains, since baseflow at the
land sites was! elevated at this time. Also more nitrate-nitrogen
is remoyed from the water by growing algae in summer than winter.
In the tidal and freshwater tributaries, (Figure 27c-d) elevated
concentrations occurred j during the summer months. Nitrite+nitrate
nitrogen concentrations in the tributaries were generally an
order of magnitude greater than in the estuarine waters . year
round. Concentrations decreased toward the Bay, however the
57
-------
mg/1
I I
t
i I
I I
I !
,
i <
I "
-.I
.. >
.-frff-- A. jr..:.->> A51*1 y, ป.
r
AMJJASONDJFMAMJJASONDJFM-AMJJ
1
1980
1981
NOTE: 22JUL81 values have been
divided by 10.
. : <-WlB
A- i---.-:STR3
Figure. 25. Time-series )plot of total phosphorus, Stations
W|B, WBS1, and STR3.
58
-------
CONCENTRATION Oh DISSOLVED SILICA (MG/L)
/ \'
*--= /\/. ; \ I -\ f
\ \ / v. / \ i ; \ / /
k ' ' i \ v / i ' '
\ \; N / /
\ \.' .- / \ \ / /
\A " / \/ /
> \ i < *
\ / ; ', v /
v \ A ,' k
AMJJA SONDJFMAMJJASONDJFMAMJJ
1979 1980 1981
OTRijOH ป.-ป-.. ii'jil ^.-ป W'.b
Figure 26. Time-series plot of dissolved silica at WBS1 and W1B.
-------
0.50 -j
NITROGEN CONCENTRATIONS (MG/L)
Station WIT
.
K / \
i \ / \
i \ / \
i v \
; \
1 f ! \ ' \ : \
] v I / \
] .' \ ' \ \ < : /
1 :\ I ' :;, .' \
5< Ammonia-Nitrogen
A M J J -A SO N D J- F M A M J J A S 0 N D .J; F M A H J J
1979 ' 1980 1981
Figure 27a. Time-series plot of--nitrogen specie concentrations, Station WIT.
-------
NITROGEN CONCENTRATIONS
Station WBS1
(MG/L)
-.
i
.-K J i
i I
1 \
j I
0
2.7U
O.SC
1 I/'
A. * '
I'
y * - * > Organic Nitrogen
?>-3--D Nitrite + Nitrate N
ซso Ammonia-Nitrogen
AM JJASONDJFMA MJJASONDJFMAM JJ
1979 1980 1981
Figure 27b. .Time-series plot of nitrogen specie concentrations, Station WBS1,
-------
ro
'"]
.00 -I
1
,,, j
NITROGEN CONCENTRATIONS
S tatron-STR4
(MG/L)
i!
I
( i ^_.^-* Orgartic Nitrogen-
I I t-3-?>-c Nltrl-t^-^-- Nitrate Nitrogen
j I -7.o Ammonia-Nitrogen
o
f.
0
0
3
0
C
c
0
" -
.70 J
.50 -
.'>0 -
.40 -
.30 -
.20
.10 -
.00 -
A
i \ J
1 x ' \ \ r~~ UI\
l| \^'< ,'^ e. ^wf v
{ ' \ ' * r~\/'\ j %..a
i i ' * ' i e t-"-ii-ซ-r''"^>4 ^
* ?* ' S ' Ss V rt- -B^l
' ' ^ '\r% ^ '' '" "' fe''1
M JJ ASONDJFMAMJJASONDJFMAMJJ
1979 1980 1981
Figure*27c. Time-series plot of nitrogen specie concentrations at Station STR4^
-------
NITROGEN
CONCENTRATIONS
(MG/L)
Station STR11
oป
co
G -70
C .DC
*.._ป Organic Nitrogen
rS^:-?' Nitrite + Nitrate Nitrogen
.-._ .-.. .1 Ammonia-Nitrogen
M . A S O N D J 7 M A M
X) N D J F M A M- J
Figure 2-7d. Time-series plot of-nitrogen specie concentrations,
-------
correlation with salinity was poor which indicates the advective
dispersion is only one of the factors controlling nitrite-nitrate
nitrogen levels.
Monitoring for nitrite-nitrogen began in April 1980; thus a
16 month record is available. Concentrations were generally
below c-atection limit in the estuary throughout the year. Of 527
samples collected, 57 were above the detection limit of 0,01
mg/1. Highest values were present in the tidal and freshwater
streams.
i.i
Both dissolved and total ammonia-nitrogen were highest in
the brackish regions of the estuary, especially in Fox Mill Run.
Concentrations peaked during low flow, and warm temperature
months (Figure 27a-d}.; |
Total nitrogen to total phosphorus ratios indicated the
estiiajry to be generally phosphorus-limiting throughout the year.
There were exceptions, however. Nitrogen-limiting conditions
would occur occasionally during the summer months in the
downstream, Bay-dominated waters; the freshwater streams and the
more Brackish regions of tihe estuary had similar exceptions
during the spring. Most notably, FM2 was the only station that
was always nitrogen- limited 'year round; Similar conditions were
present upstream at STR3, although during the first year of study
(prior to records at FM2); i which was also a "wet" year, STR3
became phosphorus-limited on two occasions
i
Suspended Solids
'; '
', Suspended solids data showed no overall seasonal trend.
Peak vaJ aes appeared to be more closely associated with rain
events or increased base flow conditions as/measured at the USGS
gaging station on Beaverdam Swamp, than with the seasons.
Elevated concentrations at \such times may be due to greater
nutrient inputs from increased particulate matter, a factor
favoring phytoplankton bloom conditions.
1 , \
Greatest concentrations of suspended solids were present in
the tidal marsh waters on anlannual basis, and decreased with
distance downstream. Lowest annual values we::e found in the
surface'waters near the mouth (WIT, W2T, W3T).
'\ \
Suspended solids were generally twice as high in the marsh
region as in the freshwater stream sites: this probably reflects
greater chlorophyll-a levels present in the marshvthan in the
stream stations (See Figures 21 and 28). '
Because of the low concentrations present in the top waters,
it appears that the Ware River subestuary may act as a sediment
trap and thus ^Ls not exporting suspended solids into Chesapeake
Bay. ' ' ' '
64
-------
TOTAL FILTERABLE SOLIDS
CTl
tn
(MG/L)
ONDJF MAMJJ
A M J
A S 0 N DJ FM A M J J
1979 1980
WIT
Figure 28. Time-series plot of total filterable solids at WIT, -WBSL,: and STR4.
-------
2.4 SPRING SURVEY 1981
During the spring seasons of 1979 and i960, distinct
increases in chlorophyll-a concentrations were noted in the Ware
River estuary. Chlorophyll-a levels of 25-35 ug/1 were observed
which is several times the annual average of 9.5 ug/1* The
blooms were concomitant with sharp increases in water
temperature.
A spring sampling survey was designed in early 1981 to see
if a chlorophyll-a maximum would once again occur. Frequent
sampling was planned so as not to randomly "hit or miss" such
ephemeral phenomena; sampling was (to commence before water
temperatures warmed to 10 C since most biological activity o'ccurs
thereafter.
On March 6, water temperatures were recorded at 6.5 C
(Figure 29). Two stations in the upper estuary were1 selected and
outfitted for continuous monitoring using automatic samplers 4t
that time. Composite samples (200-mi aliquots of water drawn
every 30-45 minutes) were collected three times weekly and
analyzed for a suite of nutrient parameters (temperature,
salinity, dissolved oxygen, suspended solids, chior'ophyll-a,
pheophytin, silica, orthophosphate filtered, total phosphorus,
dissolved and total Kjeldahl nftrogen, filtered ammonia nitrogen,
filtered nitrate-nitrogen and filtered nitrite-nitrogen).
Phytoplankton enumerations and identifications were conducted
simultaneously. This sampling schedule continued for 3 months,
lasting unitl June 5, 1981.
physical Processes
The mean salinity of station Goshen (rivermile 5.Q) was
20.9% during the period and station Pig Hill (rivermile 6.3'). was
14.6% (see Figure 30). Temperature was not significantly
different between the two stations and rose 20 degrees C in the 3
month.period, from 6.5 C to 26 C. . .
Biochemical Processes
Dissolved oxygen (expressed as percent saturation of
dissolved oxygen) was significantly higher at Goshen ,ihan Pig
Hill and became supersaturated on occasion, particularly at' the
time when chlorophyll-a levels were at a'maximum (Figure 31, May
15-25). Supersaturated oxygen conditions were riot rioted'.at Pig
Hill, although both stations followed a1 similar patter^ during
the period. I
66
-------
X.
i
p
71
n r
i if r 1 i"; ' ;
*r-.
- --. /. !,';',(: EN + -*~ + F'G HILL
FJguri: 29. Time-series temperature plot during 1981 Spring Survey.
67
-------
SALINITY
00
L. f- """
21-'
.
"5 O
i- ' J ~
'
i'J-'
P ;!,:
r
i
;cj-
A*.
/ s A- ^
x \ ,.' &
\ ..A
* ' >- / ^V /.-AX
1 ' -A-A . ^ 1 A
1 / '* A
1 1
1 /
II
4
A
/ \
/
/ v
/
.V
1 .
f
1 1
SI
.1
A
I.FV.! '::; '.TF-v!Otl ./.-.v * '.;Or.,HEN -(--ป--ป- Fit HILL.
Figure 30. Tlme-sories plot qf salinity concentrations during 1981 Spring Survey.
68
-------
1---.CH
130-
, 10-
r
F
r
L
N
T
JO-'
pISSOLVrD OXYGHN (Pf.RCrNT SATURATION)
V
i\
i
i
I1
l'
i >
I >
i i
i '
l i
l .(
l i
l i
'' l\
i I .
I-
.-* i
1 t.
I \
'I'.
I:
i.rcIN'; i :.- A- r;rjrjHEN + *-* P'r..: HILL
Figure 31. Time-series plot of dissolved oxygon percent saturation duping 1981
Spring Survey.
69
-------
As might be expected, Pig Hill had significantly higher
nutrient concentrations than Goshen for total phosphorus,
Kjeldahl nitrogen (both total and dissolved forms), silicates
and suspended solids. Combined with the knowledge that oxygen
levels were greater at Goshen than Pig Hill this tends to imply
that the marsh region of the estuary was acting as a source of
nutrients and that overall nutrient concentrations declined with
distance downstream. Once again dilution of nutrient-rich marsh
waters by tidally driven Bay waters in determining estuarine
water quality wad evidenced.
I ' ,' '
Total nitrogen levels were roughly the same at the two
stations (Figure 32a. and b) and slightly increased during the
study period. Particulate and organic-nitrogen predominated
throughout the period. There was not a significant difference in
dissolved inorganic and organic nitrogen between stations,
however significantly greater amounts of ammonia-nitrogen were
present at Pig Hill than Goshen. Nitrate-nitrogen was present
until mid- April and declined thereafter. Overall total nitrogen
seemed to increase during the period at both stations.
i|
There was a significant diference in total phosphorus
between the 2 sites. Very little orthophosphorus was detected
during ' the study, (Figure 33a and b) therefore the majority of
measurable total phosphorus was in the organic and particulate
traction; Similar to nitrogen, concentrations tended to slightly
increase with time. |
TN-.TP ratios
l
Orthophosphates were generally below detection limit at
both stations throughout the study period therefore atomic ratios
for dissolved, inorganic.nitrogen:dissolved inorganic phosphate
were not calcuable. TN:TP ratios could be calculated, and both
stations had high ratio values (over 16) which tends to indicate
that the system was phosphorus limiting. Overall, TN:TP ratios
were lower at Pig Hill( than Goshen, (Figure 34) and values at
both stations appeared to slightly increase with time.
\ x \
Chlorophyll-a values were very similar at the two sites and
rose gradually from a low of less than 2 ug/1 during the period.
Cpncentratibns peaked on 22 May 1981 (Figure 35) and returned to
a\ more typical value of 10(ug/1 thereafter. Although values are
subject to much temporal and spatial variation, the 1981 spring
chlorophyll-a values appeared to differ from the two previous
year's valuer: il both quantity, quality and time of year:
Spring 1979: High values were only present at the downstream
stations (> 35 ug/1 in April). Elevated concentrations
durated through the next 2 slackwater surveys. No bloom was
measured in the brackish area until June (27 ug/1).
v \
Spring 1980: Bloom conditions were present all over the estuary
by March 19tln (> 30 ug/1), Similar to the previous spring,
elevated concentrations were found at successive samplings.
70
-------
NITROGEN sprcirs
ONs GOSHEN
mg/1
S -
NH3F
NO:
Flf-uro 32a, Time-series hiKtogram of nitrogen specie concentrations
at Goshen during 1981 Spring Survey.
71
-------
spr.cirs
NsPlG HILL
rag/1
T
,
I
:
** ~
**
H
I
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lit
15 1 15
MARCH APRIL
**ซ
ill
*ซ*
Mb
n h
r~
1 15
MAY
IF"
. 11
Figure 32b. Time-series histogram of nitrogen specie concentrations
at PiR Hill during 1981 Spring Survey.
72
-------
PHOSPHORUS spr.cir.s
mn/,1
C . 3J -
!
0.30 -
'
0 C 7 --
0-"> '
ป_ M
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r. ^ i
W * tป 1
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MARCH
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15 1
APRIL MAY JUNE
PRTHOPHOS.
33a. Time-series histpgrar. of phosphorus specie concentration
at (.osnen, 1981 Spring Survey.
73
-------
PHOSPHORUS SPF.CirS
SIP1 !ON = n& HILL
me/1
C.I
0 :j -\
M
F"
U-V-'
15 1 15
MARCH APRIL
]f
if
IF
41
MAY
.
u
^:^1 ORTHOPHOS LTl^-J :'r-^ '
Figure 33b. Time-series histogram of phosphorus specie
concentrations at Pig Hill, 1981 Spring Survey
74
-------
NITROGEN : PHOSPHORUS ATOMIC RATIOS
55
50
40
35
3D
l\
I \
M ?
\''
i
'/I.';;; \\
' AVA i
i-r\: & i
A
rj'T!T r~: i m '.-'.'f. 'TiT' i nT'iTT'
15 1 15 1 15
APRIL MAY
JUNE
A -f.-.-T GOGH
Figure 34. Time-series plot of TN:TP ratios during 1981 Spring Survey.
75
-------
ug/1
CHLOROPHYLL A
r, !
"
: \ * J. -
v i >- -j;
V* V'|^'
j
-L..
"f ::'!": :':'! ' I'' ^ M : ; | :T ! : :'| r :- ; ; : |-rr
15 1 15 1 15 1
MARCH APRIL MAY JUNE
. i . . l
r i p r t . ป i
j H ' , .; 1 1
.v A -,' COWMEN
P!G HILL '.
Figure 35. Time-series plot of chlorophyll-a concentrations
during 1981 Spring Survey.
76
-------
L-. ..
i
peak values appeared to durate longest in the brackish area/
especially at FM2 and BS8.
Spring 1981: Chlorophyll--a values remained low, and did not rise
above 10.0 ug/1 in the estuary until May 26th. At that
time, highest values were at W5 (15.0 ug/1). Thereafter,
values were greatest in FM2 and BS9.
Phytoplankton Quality
Green flagellates (ChloreJla) were the dominate organism
when the chlorophyll-a maximum occurred in the spring 6f 1991.
in previous springs, diatoms had been the dominant organism, .It
should be noted that diatoms were persistant throughout the
period in 1981 and were next in brder of frequency fpllow'ed by
cryptomonads (Figure 36a-b). Dissolved silica was not highly
correlated with either diatom cell counts or salinity (Figure
37). Silicate concentrations at 'Cosheri were elevated prior to
peak diatom counts and remained somewhat low thereafter, which
suggests uptake by plankton. \
Rainfall:
Rain and freshwater flow as measured;at the USGS gaging
station on Beaverdam Swamp were below average during tlie spring
survey (Figure 39). Rainfall of one-half inch or more tende'd to
produce increased suspended solids (but decreased nutrient-
levels) in the study area. The response was most dramatic at Pig
Hill (Figure 38). Similarly, drops in salinity following 0.5
inch rains could be seen best at Pig Hill.
The 1981 Spring Survey compared with the overall spring
trend data of 1979 and 1980 as follows: temperatures were
slightly lower, salinity and percent dissolved oxygen were
somewhat higher than the preceeding 2 springs.
Chlorophyll-a, silica, suspended solids, and total
phosphorus concentrations were somewhat lower in 1981, whereas
total Kjeldahl nitrogen (both total and dissolved forms),
ammonia-nitrogen and nitrite+nitrate nitrogen were slightly
higher. interestingly enough, the spring 1981 standard
deviations were similar if not slightly higher than the 1979-80
spring periods even though automatic samplers, which tend to
eliminate variability in collection techniques, were used to
collect the data. Higher variation may have resulted from l) the
lowering of detection limits during the second year of study and
2) the fact that the automatic samplers composited water
throughout the tidal cycle, as opposed to sampling at highwater
slack only.
77
-------
PHYTOPLANKTON CULL COUNTS
STRTION-GOGHEN
cells/ml
n ( pp
i J _> \j \j
o n p r p _
3 ซJ ซJ -' sJ
"
15
MARCH
i is
APRIL
M
N
P>
M lili
15
..1
MAY
JUNE
DIATOMS'
CRYPTC'
CI.-JEL.TJ
Figure 36a. Phytoplankton cell counts at Coshen during 1981
Spring Survey.
U'i.i;. Fi.ACf.'ii. ::,? oo,r^';'j WLR*; DIVIDED BY 100
78
-------
PHYTOPLANKTON CF.LL COUNTS
STnTION:FIG HILL
cells/ml
6GCUO -
40GGG -
30CCO -
H
APRIL
1 15
MAY
i
JUNE
Dnri
DIATOMS
CRYPTO
Nf'LG
Figure '"fib. Phytopl.-mkton cell counts at Pig Hill during
19fll Spring Survey.
i,:'Lf!J :'l.A(-;;!.ATE r'Oc'JTS \VERF DIV.DED f^ 100
ON ro :;.AY :93i
79
-------
DISSOLVrD SILICA
: .71-:-
1
'""-?' 1
q
]
a
'"I
i v : fir r y p. V 1 MM
U I -^ I J . * ป/ I i ., I J
fjf--'
-*--+?- PIC/HILL
Figure 37. Time-series plot of dissolved silica concentrations during 1981 Spring.
80
-------
TOTAL SUSPtNDrO SOLIDS
40--
35-
30-
c. J -
K:n^r,-
!..:.< cu-11-?;; A .-, -.--. C/D^CEN + +t- PIG HILL
Figure 38. Time-neries plot of total suspended soldis during 1981 Spring Survey.
81
-------
2.4.1 TWO DAY vs. ONE MONTH SAMPLING INTERVALS >.
How representative are data collected once a mpnth in the
Ware River? By calculating monthly averages' for spring composite
samples a comparison was made'between data collected every 2 days
(although composited during the period) vs. data collected once
per monthi Comparisons were made at both stations for the 3
month period and e\re summarized in Table 3. ' <.
Interestingly enqugh, the variation between automatic
sampler dat^ collection and slackwater grab-sampling methods was
less than the seasonal variation. Exceptions to this were
suspended solids, and chlorophyll-a concentrations. Suspended
solids showed the greatest discrepancy; in all case the automatic
samplers obtained higher values than the slackwater grabs. This
may be oue to the fact mentioned above, that composite samples.
contained water collected over the entire tidal cycle as opposed
to grabs obtained at (high) slackwater only. Chlorophyll-a data
varied less than suspended solids; however, chlorophyll-a varied
in both directions, 'therefore it is inconclusive, whether either
technique overestimates or underestimates phytoplankton
populations, or whether the difference represents environmental
or diurnal variations.
Overall, composite values tended to be slightly higher than
grab sample values for other parameters as well (Table 3). Such
discrepancies can be attributed to either spatial differences, or
the effects of sampling throughout the tidal cycle. Synoptic
sampling, in the Ware River during Intensive surveys has shown
very little variation laterally and longitudinally in the
estuary; however temporal differences exist, especiallly in .the
upstream area. Therefore, it is.presumed that differences in
values are attributable to .diurnal factors such as tidal cycles
more so than spatial variations. . .
82
-------
Table 3. Comparison of Monthly Averaged Composite
Sample Values vs. Monthly Slackwater Values
GOSHEN
Parameter
S.S.
Chi. '
Si.
TP
TKN
NH3F '
N02N03
S.S.
Chi.
Si.
TP
TKN
NH3F
N02N03
S.S.
Chi.
Si.
TP
TKN
NH3F
N02N03
Auto
Sampler
12.0
1.0
.36
.04
.46
.03
.03
12.2
3.32
.71
.05
..61
.04
.02
16.2
11.9
.81
.08
.81
.01
0
Slack
1.75
1.35
.28
.02
.39
.01
.01
4*25
2.9
.63
.03
.56
0
0
9.5
13.6
.94
.08
.80
0
0
A
MARCH
+ 10.25
> 35
+ .08
+ .02
+ .07
+ ,02
+ .02
APRIL
+ 7.25
+ .42
+ .08
+ . .02
+ .05
+ .04
+ .02
MAY
+ 6.7
- 1.7
.13
-
+ .01
+ .01
-
Auto
Sampler
23.5
2.3
.99
.06
.62
.08
.04
19.9
4.1
1.49
.07
.8f
.07
.03
20.9
10.4
1.13 ..
.09
. .87
.02
.00
PIG HILL
Slack
11.25
' 6.35
1.2
.04
.53
.08
X06'
6.0
2.8
1.25
.04
.68
0.0
0,0
16.5
9.9
1.2
.09
.89
0 (
6
A
+ 12.25
- 4)05
r?|
4- .02
+ .09
-
- - .02
\ i.i.
+ 13.9,
t I-3
+ .24
+ .03
+ .16
+ .07
+ .03
+ 4.1
+ .5
- .07
-
.02
+ .02
-
83
-------
2.5 ASSESSMENT OF STORMWATER IMPACTS IN THE ESTUARY
A survey was conducted in the spring of 1980 to provide
information on estuarine response to organic pulse loads caused
by runoff. A series of nine high water slack surveys were
conducted over a 20-day period (April 25 - May 14, 1980) to study
a major rain event. Following a nine-day dry spell (previous
spring dry spells lasted for only 3 days, see Figure 39), an
average of 8 cm (3 inches) of rain fell in the watershed over
several days, just after(the spring application of agricultural
fertilizers. Nineteen nutrient parameters were selected to
detect enrichment; discrete water samples were taken at 11
estuarine and 4 freshwater stream sites. These results were
compared against annual trends which had been obtained through
semimonthly slackwater sampling during both wet and dry weather
conditions,
! Extremely low nutrient concentrations for silicates, total
and orthophosphates, suspended solids,, organic nitrogen, and
litrate+hitrite nitrogen | were found in the estuarine mouth
waters. . Moderate nutrient enrichment levels were generally found
upstream. Statistical comparisons between stations using Duncan's
Multiple Range Test (see Section 2.1.4 for a description of the
':est) showed the mouth and j headwater stations to be different (a=
6,05) in mean nutrient concentrations for 11.of the 19 analyzed
parameters. Based on thisjdistinction and the fact that salinity
consistantily varied by 5 T 7 ppt, the river was divided into 2
groups; reflecting brackish (upstream) and downstream stations.
These two groups were also compared with the two freshwater
tributary stations in order to assess the estuarine responses to
organic pulse loads resulting from runoff.
An initial dissolved oxygen sag was observed at the
brackish stations following the first day of rain (Figure 40).
Dissolved oxygen concentrations ranged from 4-5 mg/1 representing
a \ decrease in oxygen of about 2.2 mg/1 from the seasonal mean of
6.8 /mg/1. Rimer (1973)\noted that in the Neuse River, NC,
stormwater ruroff generally depressed oxygen concentrations below
the antecedent level by about 1 mg/1, and that oxygen depression
lasted for less than a day! Two closely spaced storms could
cause af decrease- in dissolved oxygen of greater than 3 mg/1.
Patterns in the Wars generally were similar , but the sag period
lasted longer, with maximum sag occurring 24 hours following the
last rainfall . Concentrations below 4 mg/1 were measured in the
marsh aroa (BS2, BS6); on May 30 and May 14, oxygen values less
than 4.0 my/1 were present throughout the brackish region (W5,
^FMl, WBSl,-pS2, BS6). Dissolved oxygen curves fluctuated due to
the numerous and often consecutive days of rain during the
survey. This, plus the intermitten-t sampling limit the analysis
of this data set.
84
-------
Df.'.tV MEAU DISCHARGE kfvl ปw) RAINFAi.'. (m.|.
USGS GAGING STATION. f-EAVERPAM SWAMP
Figure 39. Rainfall end baseflow during the study period.
85
-------
AIk.* MtAN t>tSCHฃRGC icn! end HAWAII Im.l.
USCS CAGING 51*1 OS. BLAVED2AW
DAILT ItW MSCHปR5[ ATiu RAINFALL
US6S GAGING STATION, DEA'.tF3AT *A",P
US6S 6A5!flt STATiON, BฃA'/ER3ซ1 SKAT1P
Figure 39 (contifiued). Rainfall and baseflow during the
study period.
86
-------
CO
z.
o
cr
CO
z.
UJ
u
or.
UJ
o.
UJ
X
o
Q
UJ
O
CO
CO
a
I 10-
100-
90-
80-
70:
60-
50-
40-
30-
20-
1
rO.9
-0.8
-0,7
-06
BRACKISH
V
-0.2
-O.I
--0.0
25APR
1980
27
29
I MAY 3
1980
II 13
to
UJ
o
2
-0.5 ~
- _i
_)
>.4 <
z
DATE
FIGURE 40. Relationship between dissolved osygen percent saturation and. rainf all.... Bar eraphs. ...
: -' ''reflect storm events in inches .of -rainfall. Circles represent sampling dates. 'Note
initial DO sag within 24 hours of first ra-infall. Maximum DO sag in the estuary
occurred on May 10th.
-------
Chlorophyll-a values were highest at the brackish stations
24 hr after the rain began (30.6 ug/1). With continuing rainfall
and increased flow, chlorophyll-a values decreased, probably due
to dilution, but remained well above the seasonal average of 4.5
ug/1. Chlorophyll-a values downstream did not show a response
until 15 days later.
Increases in nitrate+nitrite nitrogen concentrations
following the rain event were not detected at any site within the
estuary (<0.01 mg/1 for all stations). Loftus, t et. al, (1972)
reported similar values in the Rhode River and suggested that the
turnover time for available nitrogen and/or the uptake rat;e of
the phytoplankton must be extremely rapid to explain the }.ow
inorganic nitrogen levels.. Notably, however, nitrate+nitrite
nitrogen, total Kjeldahl nitrogen, total phosphorus1, ฃrid
chlorophyll-a values exceeded seasonal averages in the tributary
stations.
Freshwater influence on the downstream stations were
minimal: salinity varied 1.5 ppt during the 20 days, whereas
upstream station salinities were lowest 4 days( following the
rainfall and averaged 4.4 ppt below'seasonal averages at that
time. Additionally, extreme stratification of jthe water column
occurred at the upstream stations (WFM1, WBS1, BS2, and BS6) on
May 2-6; an average salinity difference of 4 ppt was recorded
between top and bottom samples (average depth '= 1.2 m) .
Stratification was observed at W3 following the last day of
rainfall (May 2), where a salinity difference of 1.3 ppt was
recorded. This implies that during periods of increased
freshwater flow, a two layer circulation system may exist.
However the stratification is not ubiquitous throughout the
estuary.
in summary, preliminary results indicate that the severity
of impacts on the estuarine Ware River 'following a major storm
event are slight, although they may present short term stress
upon the system. Generally, nutrient concentrations within the
estuary did not increase significantly above prestorm conditions
for the 20 days of the rain survey. Deviations from seasonal
mean values were slight, especially at the downstream stations.
Larger changes, however, were measured upstream, where low oxygen
concentrations (<5 mg/1) were found following the first 1.5 cm of
rainfall. ' -
From this it can be concluded that although high
concentrations of nutrients may be present in the' freshwater
tributaries, the loadings are rarely detected ;Ln ihe estuary.
These results may be explained by several hydrographic features
of the Ware River basin. ' First, slow stream fldshing tide's, as
determined from a dry weather time-of-travel dye study, /^suggest
that suspended solids and nutrients associated with pair/ticulate
matter entering the streams from runoff may settle ouฃ before
entering the estuary. Secondly, there is a larger ratio of
receiving (estuarine) water to drainage area when compared to
88
-------
other larger coastal plain basins.
Finally; the effect of nutrient loadings may be most
pronounced in the estuary when water temperatures are greatest.
Higher temperatures not only tend to increase the release of
phosphorus from the bed sediments, but such temperatures are also
associated with increased biological ectivity.
89
-------
2.6 WET vs. DRY HIGHWATER SLACK SURVEYS C
The Ware River estuary generally has low nutrient
concentrations. There are exceptions, however, especially during
the summer months |.n the brackish regions were nutrient levels
can become quite high. ;
Baseline slackwater nutrient concentrations were compared
agaijist surveys conducted during periods of elevated flow, based
on data from the gaging station located on Beaverdam Swamp. .; Such
comparisons may ' indicate whether increased nutrient
concentrations are due to inputs from rain and NPS pollution or
to the.release of nutrients from the sediments or other factors.
1 i ' '
Several slackwater surveys were selectively defined as . "WET"
or "&RY", based on level of saltwater intrusion and mean
discharge data on the slackwater date (see Table 4). Note that
salinities at W5, WFM1 and WBS1 averaged less than 12 pot during
"WET" slacks, but were greater than 12 ppt during "DRY" slacks.
The; average annual percent d-issplved oxygen saturation fdr
the 3, brsckish stations = 7*9%. "WET" slack saturation values
generally fell, below 70% (Figure 41). An exception to this was
March 19, 1980, at which time the major spring phytoplan,kton
bloom was evident thereby increasing the oxygen concentration in
the water since sampling occurred around noon. On September 7,
1979, following Hurricane David, percent dissolve^ oxygen
saturation fell to an unusual low of 57.4%; April 30, 1980
(during the major stormwater survey, refer to Section 5.1). also
had especially low values, or 56%. Average values for "WET" and
"DRY" periods were 71% and 77% .respectively. Saturation trends
were generally similar downstream as well, although values were
slightly lower.
Chlorophyll-a data showed seasonal spring peaks and as such
did not acutely relate to rainfall. The impacts of runoff
appeared to produce an uneven chlorophyll-a response throughout
the estuary which is to be expected since plankton growth is
likely to lag behiqd rainfall events.
Slackwater runs were conducted before and after Hurricane
David, a heavy fall storm in 1979 producing 12.7 cm (5 in) of
rain. On September
1979, suspended solids values in the
brackish region averaged 14.7 mg/1. Following the storm,
suspended solids, in the same area more than doubled, averaging
38.3 mg/1 (Figure 42). Stations W4 and W5 had the highest
concentration of: suspended solids on that date (71.0 and 63.0
mg/1 respectively). It appears that suspended solids
concentration in the estuary, may be dependent upon, storm
. \ ' /*
90
-------
Table A. Comparison of Average Salinity and Daily Discharge Between
"Wet" and "Dry" Slackwater Surveys.
DRY SLACKS
USGS gaging station
Beaverdam Swamp
WET SLACKS
USGS gage sta.
Bvdm. Swamp
date
June
July
Aug.
Sept.
Dec .
-May
June
27,
1*.
22,
A,
18,
12-,
12 ป
1979
1979
-1979
1979
1979
1980
1-980;
average salinity Daily
atW5, WFM1, WBS1 discharge
(cfs)
12
15
13
1A
L2
U
1A
.1
.0
.6
.2
.6
A
.7
3
2
8
13
9
-11
10
.3
.1
.2
.0
.-6
.0
.0
average salinity Dai]
date at W5, WFM1, WBS1 disch;
(cfs
May 1,
May 15
June 6
Sept.
1979
, 197.9
, 1979
7, 1979
r.ov. 20, 1379
March
April
9, 1980
30, 1980
10.
5.
9.
ป.
11.
10.
8.
6
1
A
0
2
2
9
9.8
16.0
12...0
33.0
15.0
13.0
20.0
-------
1C
ro
iUO-
130
50-
DISSOLVED OXtGEN PERCENT SATURATION
a BOTTOM
TOP
o BRACKISH
A STREAM
M
A S
1979
N
i-
M A
1980
J *
M
FIGURE 41. Dissolved oxygen percent saturation at estuarine and freshwater stream stations, April 1979 - June 1980.
Large arrows indicate "Wet" highwater slack survey-.; small arrows represent "Dry" highwater slack
surveys-
-------
ซ BOTTOM.
TOP
o BRACKISH
SUSPENDED SOLIDS
M
1980
FIGURE L-) Suspended solids concentrations at estuarine and freshwater stream sites, April 1979 - June 1980.
Large arrows indicate "Wet" highwater slack surveys; small arrows represent "Dry1 highwater slack
surveys.
-------
intensity since there was no obvious relation to discharge, nor
to season. .
Total phosphate, which is oftentimes associated with
suspended solids, was highest in the streams and showed ho
obvious relation to discharge. Orthophosphates were also of
greatest concentration in the freshwater tributaries, but did
appear to show a direct response to rain (Figure 43)^ rathetp than
increase due to rainfall, levels would drop reflecting dilution
from increased baseflow. '
Levels of nitrite+nitrate nitrogen were an tirder of
magnitude greater in the freshwater tributaries than in the
brackish regions. Values were often less than 0.01 mg/1 (below
detection limit) towards the mouth of the 'estuary'.
Nitrite+nitrate nitrogen concentrations showed a direct Response
to storms of >1.3 cm (0.5 in) total rainfall withit) 72 hours
(Figure 44), although stormwater responses were not evident in
the brackish area during the winter and early spring months, or?
times of saturated soils and maximum runoff (dilution) per cm of
rain. . '
/'
Biological oxygen demand in the bradkish region generally
increased in response to rainfall coincident with increased
inorganic nitrogen and phosphorus inputs to the estua,ryj,
Responses were not discernable downstream for this parameterr
Rainfall and runoff may exert impacts upon receiving waters
which are independent from seasonal tendencies through increased
nutrient loading to the estuary. The extenj;, duration and
severity of NFS pollution may vary'greatly dependent upon amount
and intensity of rainfall and time of year (temperature and
vegetation influences). Generally responses in the estuary are
short-lived; the increased nutrient loadings are offset by
dilution upon entering the broad reaches of the estuary.
Results from the trend data also suggest that increased
nutrient concentrations in the sprang and fall are probably due
to runoff contributions, and inputs in the form of marsh debris.
During the summer, or times of' low' flow and high temperature,
nutrient cycling and release fron\ the sediments may be the
primary factor controlling nutrient levels in the estuary.
v /
94
-------
U1
r-i .18 4-
LU
Q-
g
-t
SI
o
ce
o
Q
UJ.
o
to
to
12
o.oo-
U I
DISSOLVED ORTHOPHOSPHATE
r
\
4-
y
FIGURE 43. Dissolved orthophosphate concentrations at estuarine and freshwater stream stations,
April 1079 June'1980. Large arrows indicate "Wet" highwater slack surveys; small
arrows represent "Dry" highwater slack surveys.'
-------
to
.35 --
.30 -
LU
ID
O
c:
LU
I-
<
cr
LU
c;
.20 -
.15 -
0.00
t o
e e
H 1 1
h-
+
-I 1t-
H 1-
1 3 5 7 9 11 13 15 17 19 21 23 75 27 29 3133 35 37 39 41 43
RAINFALL
FIGURE 44. Relationship of nitrite'+nitrate nitrogen ..concentration to rainfa.ll,..
' "'".'..-.'"- "'in. the upper"estuafy-.'
-------
2*.^ OTHER TOPICS
Several topics which haซjje been investigated did not fall
into any of the preceeding \6aitegories. These include discussion
of the transition zone ancj the turbidity maximum'.
; 2.7.1 TRANSITION ZONE
When the W,are project Was initiated, little
data was available for the design of the field program, It
telt necessary to differentiate between the two freshwater
tributaries, but shallow mu,d flats made it difficult to proceed
upriver much beyond Warehouse Landing. Therefore, the two 'mos.i
upriver stations in the 'estuary were located in the two
tributaries just upriver of the confluence. Atf that time it was
anticipated that the salinity at these stations would be' very
low, since they are about two-third's of tHe way upriver froih the
mouth to the limit of tidal influence. Field data have ^how'r.
that this is not the case. In addition, nutrient coricentra^'ipns
at these locations were found to be higher than in the lower
estuary. Therefore it was decided that this region merited
further attention.
The reaches of the tributaries between Warehouse Landing and
the upper limit of tidal oscillations includb extensive marshes.
Several preliminary surveys into the marsh or oligohaline (0 to 5
ppt). region revealed large fluctuations in the degree !of
saltwater intrusion and high levels of total phosphorus and'
dissolved silicates.
On April 17, 1980 two stations (BS2 and BS6, see Appendix A-
1) in the marshes of Beaverdam.Swamp were occupied from 0900 to
1300, or frcra about two hour's befoe high water slack until two
hours after HWS. Boats were' anchored at the stations,.hand-held
current meters (Byrne and Boon, 1973) were employed and water
samples were collected for dissolved nutrient analyses. Velocity
readings, staff height, dissolved oxygen and salinity were
measured every li minutes; nutrients were sampled hourly. '
The survey revealed several interesting features. Maximum
currents observed at BS2 'a/id BS6 were 0.31 and' 0.44 m/sec
respectively, and occurred approximately 45 minutes after HWS
(Figure 4.5). The velocity yas higher at BS6 presumably becaiue
the channel is narrower and deeper. Temperature's rose from .9.5 G
(0900 hours) to 13.0- C during the1 study.
Dissolved oxygen ranged from a morning Iciw of 6.6 to . d.6
mg/1 just before noon at BS2, and 7.2 to 8.9 mg/1 at BS6.
97
-------
UD
00
o
LU
CO
cc
5-H
.41
Q -3
LU
ID
Q.
CO
-2 -
.1 H
0.0
FLOOD
._0.,
,
0900
1000
.o
^ -.BS-6
- BS2
iroo
1200
1300
r
TIKE (hours)
FIGURE 45. Current speeds (m sec" ) at stations- ES2. and .-BS6, April :16, 1980.
-------
Salinity ranged from 11.5 to 12.0 ppt (top-bottom) at HWS to half
those values (5.2 - 6.3 ppt) two hours later at BS2; representing
a salinity variation of 6.3 ppt. Station BS6 varied from 8.5
(both top and bottom) at HWS to 0.4 ppt during the same time
period. This showed a strong salinity gradient present in the
marsh: fluctuations in the mainstem of the estuary over similat
time periods were about 4 ppt in the brackish region $nd less
than 2 ppt near the mouth.
Concentrations of suspended so)ids, silicates and
nitrite+nitrate nitrogen were high in the oligohaline reaches of
the Ware River, as shown in Figures 46t48. Nutrient
concentrations were lowest at high water slack, indicating that
these waters are enriched relative to the Bay-derived waters near
the mouth. The elevated nutrient levels may be'asssociated with'
groundwater and surface runoff or they may represent an export
from the marsh. '
... i
Chlorophyll-a values similarly were greater in the mejrsh
than at VJBSl. Total phosphorus values decreased from BS6 to BS2>
perhaps as a result of adsorption ancl settling. Mote baseline
information is needed on the marsh area before export/import
L.L>nc.LUsions can oe drawn. wonetneiess, in tne harrow marsnes,
nutrient: ieveis riuctuate more rapidฑy ana to a larger extent
tnan in tne proader snanow reacnes at WBbi anq WM*II near tne
conriuence. Because times or maximum currents occur7 witnm less
tnan an nour oetore and atter HWS, it becomes imperative to stay
ciose to siacK time tor sucn studies, ir tnat is tne/oasis u'pop
wn.icn aaca is to oe intercompareci.
99
-------
70-
-1.6
-? 60-
0 SUSPENDED SOLIDS-"
SILICA
-1.5
o
. o
co. 5.0-
o
co
2
Q
C.
CO
CO
30-
HWS
N ' /
^L '
\
20.
09^0
idoo
ll'OO
12*00
13\)0
. ll.l
TIME (hours)
FIGURE 46. Concentrations of suspended solids and silica at station -BS2, April 16, 1980.
-------
a
UJ
50
CO
a
^ 40 -
o
CO
35 -
SUSPENDED SOLIDS
\
V-
HWS
h
n_
. in
to
30 - o TOP
A BOTTOM
""" 6960 --;-
rood
SILIGA
1.7
1.6
1.5 t*
1.4 -
^ 1'3'
00 r TOP
A BOTTOM
1.2 ~
0900
HWS
i2i'b6"
1300'
1000
1100
1200
T"
1300
FIGURES 47 and 48.
Concentrations of suspended solids and silica at
station BS6, April 16, 19RO. Top and bottom
samples were taken.
101
-------
MAXIMUM
Alot or attention is given to tne saitwater/treshwatet
inter race region in an estuary since many dissolved forms ot
nutrients tend to tJ.6ccu.Late upon encountering saltwater, whether
due to physical mixing phenomena or chemical Reaction. This
creates an environment which is generally high in tUrbidity,
nutrient rich, and tends to contain higher concentrations ot
organic matter than those'present in either tre^n or salt water,
. i ' ", '
Such turbidity maxima have been observed in estuaries of
varying size, shape, and dynamic cnaracter; both well-mixed artd
stratified (Nichols, iy/2). As a part ot the second year plan to
emphasize study in the upstreajn areas, an initial trip was
scheduled into the tidal reaches pf'Beaverdam swamp to determine
.it a turbidity maximum might be present. On November 3, 1980, a
clear day with good water column visibility, a Turner Design
flow-through tiuorometer was used to get a rough mea'sure of
turbidity in situ. Sampling was planned around low water slack..
Monitoring began upstream ot wesi (salinity: 18.8% ppt')' and ended
downstream ot BS& (0.3 ppt), when background recordings had
returned to the baseline. '
Results showed turbidity to increase steadily with distance
upstream and peaked at approximately r'ivermiie 7*5, with a
recording five times background level.
Chemical and physical dat^; tend to lend support to the
presence ot a turbid ity maximum as well: station &S6.^ cqntained
the highest mean suspended, solids concentration oฃ any station in
the saltwater region (X=2b.5 mg/1). Concentrations tended t,6
increase with distance upstream but then declined, similar to the
fluocometric tindings. Chiorophyli-a concentrations followed the
same trend as suspended solids (Table '5).
Salinity was unusually hi9h at BS6 (1U.8 ppt), not what
would be considered indicitive ot a turbidity maximum* However
previous work (see Section 2.7.1) showed a Strong longitudinal
salinity gradient present in the marsh. Concentrations were, found
to change as much as 3-4 ppt per km in the marsh region during
LWS (Intensive Surveys 1980, 1981). Stations BS6 and BS8 are
roughly 4 km apart therefore the turbidity maximum could ve'ry
likely occur at some place between the 2 stations and presumably
shifts with season and fresh water flow*
102
-------
TABLE 5. Chemical Evidence for a Turbidity Maximum.
I A A 4k
Station Rivermile SS Chl-a Sal
WBS1 5.9 21.0 12.6 18.8
' . .
BS2 6.4 24.7 12.4 13.6
BS6 6.8 ' 28.5 17.3 10.8
BS8 9.0 13.8 12.9 0.3
i /
103
-------
t.i.i ONGOING STUDIES.
One of the primary goals ot the Ware River Intensive
Watershed Study has Deen to observe the impacts of s.tormwate.r
runott on estuarine water quality. Another important aspect of.
the problem is bacterial fluctuations due to runoff since the
Ware River estuary includes several productive shellfish areas.
A portion o.f the shellfish waters are cpndemmed for direct
harvesting because of the wastewater discharge from Gloucester
Court House. A small study is being conducted to define both the.
dry weatiher and wet weather distributions of bacteriological
indicators in the upper portions of the Ware River estuary. The
work is b;eing conducted simultaneously with an ongoing project in
the Ware River dealing with fecal coliform and pathogen
(Salmonella งฃ.) survival. The combined results will assis.t
managers of shellfish resources by documenting the temporal arid
spatia1! extent ot bacterial .contamination due to wastewater
discharges and stormwater runoff during dry and wet weather
conditions. The studies will also provide valuable information
fbr use in mathematical modeling of stormwater runoff.
Methodology '
Study, ,s:(.tes consist of four " locations previously
characterized with respect to nutrient: and physical parameters
during the first two years of the watershed study. Two sites.
have been located in the tributaries, FM2 and BS8, which drain
the upper reaches of the Ware River basin. The other two sites
are located ca. 0.7 and 2 miles downstream from the confluences
of the tributaries (Stations W5 and W4) . . ':
up to tive surveys will be conducted to establish background
trends in estuarine water quality at each site during periods of
dry weather, i.e. no rain on each of three preceding days.
Surface water (0.5 m in depth) will be sampled daily during slacH
water before flood for three consecutive days (weather.
permitting). Water samples will be.analyzed using a .five-tube
most- probable-number technique according to the Medium A-l
procedure, .modified to include a resuscitation step .for the
recovery ot debilitated fecal conforms. The modified A-l test as
approved by the' National Shellfish Sanitation Program was
selected because it allows for a rapid enumeration (within 24
.hours) ot fecal colitorms. (Also, a maximum of five storm events
resulting in raintall of 0.5 in. or greater will be monitored as
explained above to describe'"the wet weather response.
i ' k
in addition to bacteriological investigations, samples will
.be analyzed for various { nutrien*- and physical parameters i
"Specifically, dissolved oxygen, salinity, temperature, suspended
104 ':
-------
solids, total phosphorus, and total nitrogen (measured as organic
nitrogen, ammonia-nitrogen and hitrite+nitrate nitrogen) will be
analyzed.
Data will be analyzed, interpreted and submitted in report
form to both State Water Board and Bureau of Shellfish Sanitation
upon completion. .
105
-------
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Clark, L. J. , V. tuide, and T. H. Pheiffer, 1974. Summary an.d
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Annapolis Field Office, Region III, U.S. Environmental
Protection Agency, Annapolis; Md.
i J " i .
Correll, D. L. , T. L. Wu, E. S. Friebele, and J, Miklas, 1977.
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Correll, ed. Watershed Research in Eastern North
America: A Workshop', to Compare Results. Ches. Bay
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J37-344.
Edwards; R. W. and H. L. J.iRolley, 1965. Oxygen consumption of
river muds. J. Ecology; 53:1-19.
Eleuterius, C. 'K., 1976. .Mississippi Sound temporal and spatial
\ distribution of nutrients. MASGP-76-024, Gulf Coast Research
Labora-tory, Ocean Springs, Miss.
Flemer, D,, A.> D. H. Hamilton, C. W. Keefe, and J. A. Mihursky,,
' 197U. The effects of thermal -loading and water quality on
estuarine primary production. Ref. No. 71-6, Natural
Resources Institute, Univ. of Maryland, Solomons, Md.
/ ' '
Gambrell, R. P., J. W. Gilliam, and S. B. Weed, Nl975. ^Nitrogen
losses from so-'.ls of the North Carolina coastal plain. J.
Env. Qual. 4.: 317-323. ' .
Grizzard, T. J., and F. X. Brown, 1979. Noripoint sources. J.
Wat. Poll. Cont. Fed. 51(6}:1428-1444 .
! \ ' . . ^
W. S. , 1979. Npri'poi'nt s'ouire pollution control strategy.
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Martin, eds. Best Management Practices, for Agriculture and
Silviculture. Ann Arbor Science Pub., Inc. Ann Arbor, Mich.
J 06
-------
Haas, L. W,, 1977. The Effect of the spring-neap tidal cycle on
the vertical salinity structure of the James, York . and
RappahanrtOck Rivers, Virginia, UiS.Ai Estuarine and Coastal
Mar. Sci. '5:485-496.
Harms, Li L. and E. V. Southerland, 1975. A case study on non-
point source pollution in Virginia. Bull 88, Water
Resources Research Center, Va. Polytechnic Institute : and
State Univ;., Blacksbiirg, Va. .. ;,
Hobbie, J. E., 1970. Phosphorus concentrations in the Pamlico
River estuary of North Carlina. Rept. No. 33, W
-------
Neilson, B. J.f 1980. A .report on the effects of nutrient
enrichment in estuaries. In: B. J. Neilson and L, Eป
Cronin, eds. International Symposium on Nutrient
Enrichment in Estuaries. The Humana Press, Inc.? Clifton,
N.J. . ..'.,.
Nichols, M. M., 1972. Sediments of th-e James River Estuary,
Virginia. Geological Society of America, Inc., Memoir 133,
pp 169-211. . . .:.....;
Nixon, S. W., i960. Remineralization and nutrient cycling in
coastal marine ecosystems. In: B. J. Neilson and L. E.
Cronin, eds.International Symposium on Nutrient Enrichment
in Estuaries. The Humana press, Inc., Clifton, N\.J..
', .''*'' j
~ ' - . '
Ott, W. R., 197b. Environmental Indices: Theory and Practice;'
Ann Arbor Science, Ann Arbor, Mich. '
fomeroy, L. R. , L. R. Shentbn, RJ D. H. Jones, and R. J. Re imolci ,
j.972. Nutrient flux in estuaries. In: G. E, Likens, ed'.
Nutrients and Eutrophic^tion: The Limiting Nutrient
Controversy. Special Symposia, VOl. 1, Am. S.oc. 6ฃ
Limnology and Oceanography, Lawrence, Ks.
pritchard, D. W. , 1969. Dispersion and flushing of pollutants in.
estuaries. J. ot the Hydraulics Division Am. Soc. Civil
Eng.. 95CHYI) : '
\
Rimer, A. E. , J. A. Nissen and D. E. Reynolds, 1979.
Characterization arid impact of stormwater ruhoff from
various land cover types. J, Wat. Poll. Cont. Fed. 50:252-
264,
Rosenbaum, A. and B, J. Neilson, 1977; Watexr quality in the
Pagan Hiver. Spec. Hep. No. 132, Appl. Mar. Sci. and .Ocean
Eng., Va. Institute of Marine Science, Gloucester
point, Va . '
Seliger, H. H., 1972. Phytoplanhton production, growth and
dissipation in Chesapeake Bay^ Progress Rept. 15 Dec 1971 *
15 June 19/2, Rhode River Program, Ches.- Bay Ctr. for .Eniv..
Studies, Smithsonian Inst., Edgew.ater, Md.
Sokal, R. R. and F. J. Rohlt, 1969. Biometry. W. H. Freeman and
Company, San Franciso; 776pp.
Stanley, D. W. and J. K. Hobble, 1977. Nitrogen recycling in the
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Strickland, J. D. H. and T. R. Parsons, 1972. .A Practical
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Swank, W. T. , and J. E. Douglass, 1977.. Nutr'en't budgets from
108
-------
undisturbed and manipulated hardwood forest ecosystems in
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i , . .
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i - I
i \ i .
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109
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AP&ENDIX A
*f'
N|aihber ' ''Page
Arl Description of Slackwatef Sampling Stations fL.lll
Aj:2 Description of 1979 Intensive Survey Stations...;..114
A-3 Ware RiVer Slackwater Survey Dates and Times.......115
A-4 Description of Events Sampled at Each Station...... 117
A-5 Map of Bathymetric, Tide Gage and Current
Meter Locations 118
A-6 Ware River Bathymetric' Information. . ; . . . . .119
110
-------
TABLE A-l. DESCRIPTION OF .SLACKWATER SAMPLING STATIONS .
A fortnightly high slackwater sampling program on the Ware River.estuary
was initiated on April li, 1979 and continued until May 14, 1980 when
the frequency was reduced to once per month. The purpose of these same
slack surveys was to delineate seasonal trends in water quality.' During
the surveys grab samples were taken at 16 distinct locations, including
four freshwater stream sites and twelve stations in the estuary. A brief
description of the sampling sites follows. Numbers in parentheses
indicate how sample bottles were labelled.
ESTUARINE STATIONS .. .. ' , _. .
Water Depth River
Station Latitude Longitude a,t MHW Mile
Wl 37 21' 20" 7,6 24' f.2" 8.5 th 0.00
Located 50* off north side of black and white channelj marker "M2J.11.
Average depth is 8 metres.; Samples are taken one metre from the
surface (WIT) and one .Tieter from the bottom (W1B') .
i
W2. 37 22' 09" 76 26' 21'.' 5.Pm ' ]L4
Located 50' off north sj.de of green marker ,"3". Average, depth' is
5 metres. Samples are taken one metre from the surface (W2T) and
one metre from, the bottom (W2B)..
W3 37 22' 08" 76 27' 21" 5.0m 2.4
At the intersection of two lines: . (W3T and VJ.3B')
1) Line up 2 pines on Windmill Poi.nt, also passing through white
house at month of Wilson Creek.
2) Red marker "6", duck blind, Jarvis Point going to landward
end of pier.
W4 37 23' 16" 76 21,' 28" 5.0 m 3.7
Located 15' off south side of green marker "9". Average depth
is 5 metres. All samples taken at mid-depth (*M ) .
i ' i
W5 37 23' 46" 76 28' 45" 2m 5.0
Located. 15' off south side of red marker. "12''. Average depth
is 2 metres. All samples taken at mid-depth (W5).
WWC 1 37 21'. 55" 76 28' 15" .2m, 3^
Located in the center of Wilson's C-eek channel, slightly upstream
from third day marksr, siting off pier on point of land on left and
and house on point of land on right. Average depth is 2 metres.
All samples taken at mid-depth (WWC1).
WWC 2 37 21' 50" 76 28' 45" 2m 3.6 .
Located at confluence of the 2|tributaries in Wilson's Creekj siting
off pier on left and point of jand on right. Average depth is
2.metres. All. samples are taken at mid-depth (WWC2) .
Ill
-------
TABLE A-l (Continued)
Water Depth River
Station Latitude Longitude at MHW Mile
WFM t 37 24' 04" 76 29' 35" 1.2 m 5.6
Located in center of stream, siting off northernmost point on
Perrin Point and southern tip of Warehouse Landing. Average :
depth is 1.2 metres. All samples are taken at mid-depth. {JFttl) . r
WBS 1 37 24' 37" 76 20' 30" .1.2 m 5.9 .'
Located in center of stream, siting off third cusp upstream from ;.'
Warehouse Landing q'n left arid off second point of land on right.
All samples taken at mid-depth (WBS1).
BS 2 37 24' 50" 7629' 35" 1.5m 6.35
Located at mouth of marsh creek about 50' north of point which ;
divides wide section of Ware River with tidal flats from the narrow
marsh creek. All samples taken at mid-depth and in the middle .;.
. of the channel (WBS2)>
6.8
BS1 6 ' 37 24' 48" 76 29' 50" 3.m
Located in the straight section o'f the marsh creek approximately
one half mile upstream of WBS 2. All samples taken at mid-depth
: and mid-channel (WBS 6). . .-
BS. 8 37 24'50" 76 30' 45" 0.6m 9.0
Located at the head of the marsh creek where it becomes hardwood .
swamp. All samples taken at mid-depth and mid-channel (WBS8).
.FM 2 " 37 24* 10" 76 30' 30" 1m 7.4
i ,
Located 3400' downstrean from Route 17 directly underneath power '
I'tnes that stretch from Deacon's Neck across Fox Mill Run.
All samples taken at mid-depth and mid-channel (WFM2).
-------
TABLE A-i. (Continued)
NONPOINT SOURCE AND FRESHWATER STREAM STATIONS
Station Latitutde Longitude
STR 1 37 22' 16" 76 30' 50"
NFS 2 37 23' 40" 76 29' 40"
STR 3 37 24' 32" ?6 31' 06"
STR 4 37 24' 52" 76 31' 08"
NPS 5 37 24' 30" 76 29' 10"
i
STR 6 37 25' 38" 76.29* 48''
NPS 7 37 2V 52" 76 33* 25"
NPS 8 ' 37 26' 50" 76 35' 30"
STR 9 . 37 25' 30" 76 31' 45"
STR 10 37 24' 35" 76 :u' 55"
STR 11 37 28' 14" 76.33' 48"
113
-------
TABLE A-2, DESCRIPTION OF 1979 INTENSIVE SURVEY STATIONS
During the intensive survey of August 1A-15, 1979 all slackviater
stations were occupied. Additional s' ations described below, were
manned along the transects in the broader reaches of the estuary
(also see Figure A-l) {
Station Latitude Longitude Water Depth at MHW
WIN 37 ?!' 46" . 76 2V 37" 2.0m
i
(Northern shoreline). Located at intersection of one line passing
through Ware Neck Point and j channel marker "M21", and another line
passing through the two duck blinds along the shore. Average depth
is 3.2 metres. Samples are taken at mid-depth.
i
W1S . 37 21' 00"; 76 25' 10" 3.2 m. .
(Southern shoreline) - Located 400 yards off shoreline, facing middle
inlet (of three) which appears as a small, sandy beach area, and on
line with Ware River Point and a channel marker on the SE horizon.
Average depth is 2 metres. All samples are taken at mid-depth.
i
W2N 37 22' \y 76 25' W . 3.5 m
(Northern shoreline). Sampler taken 200 yards off first dock to the
west of the inlet where ttie Ware River Y.':ht Club is located, and along
a line with the green "3" channel marker.- All samples are taken at
; average depth is 3 metres. '
W2S 37 21' 57" 76 26' 29" 3.0m
i '
(Southern shoreline) . Located at intersection of transect line passing
from the white house on the northern shore, through green "3" channel
marker, ending at the clear beach area at the edge of the stand of trees
on the shouthern shore, and on line with the du"k blinds due west of
the transect. Average depth is 3.5 metres'. All samples are taken at
mid-depth.
W3N . . 37 22' 26" . 76 27' 17" 1.7 m
Located in between 2 duck blinds found along the tansect between
station W3 and the small island in mid-river. Sample 50 yards off the
north side of the southern blind. Average depth is 1.7 metres. All
samples taken at mill-depth. '
114
-------
TABLE A-3. WARE RIVER SLACKWATER SURVEY DATES' V
Sampling dates and times for hlg'hwater slack surveys are listed below.
'.n
Juf
Aujunt
:. -.vrr.-jcr
!-'obru.'iry 1'
Ma re IT
April
11
25
nl'
i r>
06
1 0
2"
1!
?.'.
0?
1 '.
r
jr
C'-
''.7
1.5
15
07
j.V
':>'
ป V*
i"
0(-
19
01
16
25
28
30
02
f-4
Ofi-
; f.'
! '
1979
1979
1 979
1 V'~9
1979
3979
iฐ79
1979
1979
i 079
3 ')* 9
i *70
is; s .
i~-79
j?79
l'?79
1979
\l&
\r>l
I ' ^ 9
1980
1-9SO
1980
1 ?80
1980 "
I9!?0 . R
1 980 R
!9FO
! 98 0 P
! ')SO R
DSd
nan o
* 9 S ^l H
nooo - i':30'
n.v.o - ' :1?0
i 1 llu ./. !*
U15
OtVo -
OPf -
i r?o -
3 Ci-.iO -
I -l ; ', _
vv'5 --
'. "."^^
:'" Vl -
^./O -.
! r^.'; -
0930 -
- f ^
^ ^ k *"^
) - ":'. -
"': ; . ' -^ .
^'00*
!.c,;i.5*
-1 3'?*
2 j 5*
2'0ปT*
i '' r>*
ilo*
'bo*
'- ;>n*
>':?*
'15*
."SCte
9i.Sv
?;r*
t :' - .
.-\3-c
;-;:2 ;?:'^
1052 - !230
HID - 1250 '
1110 - 1230
0835 - n20
0923 - IliO
0530 - 1-3C*
0915 - HG'O*
0915 - 1200*
1010 - ; :v>'-
1115 - !2'iO*
1320 - Ii3o*
:-515 - 0730'-
?7i5 - 05 5 C-
R iit- T,v:atcM' '.:r.;.'u'.:c Survey
; l):r ' i'j,h.t S<:\-in.ns Time
lib
0915 - 30-5*
-------
Table A-3 (continued).
Ware River Slackwater Survey Data
Sample
June
July
July
July
July
July
August
September
October
November
December
Januaty
Febuary
March
March
March
March
April
May
June
July
12
7
9
10
14
31
20
23
22
13
11
26
25
24
25
26
31
22
26
23
22
date
1980
1980
1980 Summer intensive
1980
1980
1980
1980
1980
1980
1980
1980
1981
1981
1981
1981 Spring Intensive
1981
1981
1981
1981
1981
1981
Sample time
0845 - 11345*
0440 r, 0715*
0935
1200
1645
0745
.0830
/
1/00
1045
1245
1200
1030
1225*
1330*
1S45*
1030*
1030*
1230
1250
1430
1340
1215
1600' + 1830
1000 V- 1130
1430 - }600*
1330 - 1515*
1420 * 1540*
116
-------
Table A-4. Description of Events Sampled at Each Station'.
Station Event Sampled
tois ii
Wl, II, SI, Rl,
WIN II
W2N II
W2 II, Si, 12 S2
W2S II
W3 . II. SI, Rl 13, S2
W3N .11
W4 . II, SI. Rl. 12, 13, S2
W5. II,' SI, Rl, 12, 13, S2
WWC1 . II, SI
WWC2 ' il. Si, Rl, 12, 13, S2
WFTiL II, SI, Rl, 12, 13, S2
/
WBS1 ,'IIV SI, Rl, 12, 13, S2
WBS2 , Rl
i
WBS6 . Rl, 12
. 12, 13, S2
12, 13, S2
Key;
Si" Highwater Slack surveys, 1st year \
II- 1st Mritensive survey, August 14-15, 1979
Rl- 1st Raihevent, Aprils-May, 1980 x
S2" Highwater Slack surveys, 2nd year
12- 2nd Intensive, July 9-10, 1980
13= 3rd Intensive} March 25-26, 1981
117
-------
FIGURE A-& "are River stations (), and locations of bathymetric transects (),
tide gauges (), and current meters (*), 1979-1981.
118
-------
A-6. WARE RIVER BATHYMETRIC INFORMATION
Transect
Wl
W2
W2 . 5
W3
wci
WC2
WC 3
W3 . 5
W4
W4 . 5
W5
WFM1
WFM1.5
WBS0.5
WBS1
Area at
MTL (M2)
8304.11
8096.98
49,76.63
3466.67
344.75
257.19
163. :05
2996135
1236.38
988.74
635.94
123.38
138.86
351.17
214.62
Riverm
0.0
1.4
1.9
2.4
3.2
3.6
3.9
3.2
3. '7
' LA
5.0
5.6
5.7
5.6
5.9
119
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Page Intentionally Blank
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