HomeMy WebLinkAbout1989 Circulation and Water Quality of Mats Mats Bayr
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A Report Prepared for
McConnell /Burke
11000 NE 33rd Place
Suite 101
Bellevue, WA 98004
CIRCULATION
AND WATER QUALITY OF
MATS MATS BAY
HLA/Harper -Owes Job No. 19436,001.09
by
Thomas J.Smayda
Aquatic Scientist
Martin E. Harper, PA., Ph.D..
Consulting Principal Engineer
HLA /Harper -Owes
1325 Fourth Avenue, Suite 2110
Seattle, Washington 98101
206/622 -0812
December 5, 1989
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An oceanographic survey was conducted in Mats Mats Bay, Washington during the
summer of 1989 to evaluate existing environmental conditions. This monitoring effort
focused on water circulation and flushing as well as water quality. Key water quality
parameters identified included nutrients, which promote algal growth, and fecal bacteria,
which may contaminate shellfish. The flushing and circulation characteristics of the bay
were assessed because of the great influence they exert on the distribution and
concentration of these constituents. Developed data was contrasted with existing Class
AA water quality criteria and with water characteristics from other embayments. Mats
Mats Bay is uniquely configured with a narrow channel through which all tidal exchange
occurs. Sampling conducted within the channelized inflow and outflow has permitted
mass balance evaluation of constituents entering and leaving the bay. Sampling has
targeted periods of low tidal exchange in an effort to identify worst case conditions.
The presented description of these results includes an estimate of the pollutant
assimilative capacity of Mats Mats Bay.
STUDY AREA
Mats Mats Bay is a Class AA (WAC 173 -201) tidal basin located on the northeast portion
of Washington State's Olympic Peninsula, two miles due north of Port Ludlow (Figure 1).
The bay is a small, sheltered basin isolated from the Admiralty Inlet portion of Puget
Sound by a narrow, doglegged channel (Figure 2). Rolling hills rise to elevations of 100
to 600 feet and surround the bay. The hilly terrain, small fetch and angled channel
combine to reduce wind and wave action within Mats Mats Bay. The' catchment area is
approximately 2.4 square miles and annual rainfall on the order of 24 inches. Runoff
from this catchment enters the bay via three small creeks. The largest of these enters
the northwest corner of Mats Mats Bay and the other two enter the southwest portion.
Approximately 85% of the catchment is vegetated, 10% is the bay surface, and 5% has
been cleared for small farms, residences, roadways, and the Mats Mats quarry.
Predominant tree species in the catchment are Douglas -fir, western red cedar, red alder,
western hemlock, and big leaf maple. Common shrubs include rhododendron, salal,
salmonberry, and huckleberry. Swordfern dominates the herbaceous layer. Soils in the
catchment (USDA, 1975) are dominated by Alderwood gravelly sandy loams with 0 -15%
slopes. The soil is approximately 20 -40 inches thick, and rests on a cemented layer.
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MATS MATS BAY LOCATION MAP
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MATS MATS BAY LOCATION MAP
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Figure 2
BATHYMETRIC MAP AND SAMPLING LOCATIONS.
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BATHYMETRIC MAP AND SAMPLING LOCATIONS.
4
{ The soil is moderately well drained and the permeability above the cemented layer is
moderately rapid. Alderwood soils are located west and north of the bay and directly
abut shorelines on the northern edge of the channel and the eastern portion of the bay.
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Cassolary sandy loams with 0 to 15% slopes are located immediately adjacent to the
southern and western portions of the bay. This is well drained soil, at least 5 feet deep
and permeability is moderately slow. Kitsap silt loams are not immediately adjacent to
the bay, but, are exposed along much of the bed of the creek which drains to the
northwest corner of the bay. These 5 foot deep soils have 0 -30% slopes, are moderately
well drained and permeability is characterized as very slow. The remaining soil in the
Mats Mats Bay catchment is an Olete very gravelly silt loam which lies in the vicinity of
the quarry on Basalt Point, east of the channel. This 20 -30 inch soil is sloped between
0 -30%. Permeability is moderate and the soil well drained.
Runoff from all of the soils in the watershed is slow to medium and the erosion hazard'
is slight to moderate. The ability for the loamy Alderwood and Kitsap soils to assimilate
pollutants from roadways, agricultural runoff, or septic drain fields is deemed to be
moderate. However, during the wet season, soils above the cemented layer may become
saturated and not function so well (USDA, 1975). The Cassolary soils, on which a
number of the perimeter homes have been constructed, may provide better treatment if
suitable travel distance through unsaturated soils exists. The Olete soils of Basalt Point
are shallow and relatively permeable which minimizes the ability of the soil column to
adsorb pollutants.
Land immediately surrounding Mats Mats Bay is predominated by single family
residences. Approximately 35 houses are located within 200 feet of its shores. There
are also two near -shore hobby farms. A quarry pit which crushes 300 tons of rock per
year is located on Basalt Point. This operation includes a fiberglass blanket screen
designed to trap suspended material which would otherwise enter Mats Mats Bay. A
herring bait facility operates on the eastern edge of the bay. Floating net pens are used
for holding live herring from 10 to 14 days (Rubida, 1989). Approximately 2.7 million
herring are held and sold by this operation annually. A commercial oyster bed has been
located at the north end of Mats Mats Bay.
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The bay is a well protected anchorage and during Summer 1989, approximately 20 boats
were moored there during midweek. Approximately 3 live - aboards were observed
anchored midweek; more than 20 live - aboards may gather during peak use weekends.
METHODS
Sample Stations. Seawater samples (Figure 2) were collected from a background station
(Sta. 1) located in Admiralty Inlet, due west of the Mats Mats channel opening and
about 1 mile offshore. A station within the channel (Sta. 2) was sampled during both
rising and falling tides on each sample date. Two stations were located within the bay
(Sta. 3 and 4). Three creek stations were sampled. Oyster samples were collected
primarily from a single station, however, on one date were also collected near the creek
entrances.
Sample Dates. Water quality samples were collected once per month between July and
October. "Worst case" conditions were targeted by the collection of bay samples during
the last half of ebb tide and during minimal tidal ranges. Tidal ranges varied from 0.6
to 13.3 feet over the study period (Figure 3A). Tidal ranges sampled ranged from 1.65
feet to 2.64 feet and averaged 2.33 ± 0.46 feet. The frequency distribution of tidal
range (Figure 4A) indicates that small tidal amplitude is fairly frequent despite the large
spread in tidal ranges. Sampled tides represent the 11% smallest tides. A small tide is
generally followed by one with great range (Figure 3A), thus even when small tides
occur, the average daily tidal range is large. A daily average is meaningful because
many marine processes, such a phytoplankton growth, are strongly influenced by events
which occur on a daily time scale. The daily average exchange based on tidal prism
during sample dates was 49.0 ± 3.4 million cubic feet, also within the 11th percentile
over the study period (Figure 4B). Drogue studies of water motion were conducted once
during a minimal tidal range and once during an average range. Together with the
drogue studies, water quality samples were collected from Mats Mats channel in support
of mass balance calculations.
Sample Acauisition. Depth composite samples were collected from each station with a
gang of Niskin bottles. Surface water was collected at the background station (Sta. 1)
from depths of 1 m, 3 m and 5 m, equal volumes blended in a large bucket and then
subsampled into the necessary bottles. Deep water was similarly collected from 10 m, 20
m, and 40 m. Composite samples were collected from the channel inflow and outflow
points (Sta. 2I, 20) and from the northern portion of Mau Mats Bay (Sta. 4) from depths
of 1 m and I m above the bottom. Three prewashed and prelabeled nalgene bottles, a
250 ml and two 1 L were filled from each composite. Samples were stored on ice in a
cooler for transport back to the laboratory. Upon return to the lab, the 250 ml sample
from each composite was acidified with four drops of concentrated H2SO4 and deep
frozen for subsequent total phosphorous analysis. One 1 L sample was whole for fecal
coliform, TKN, NH4 -N and total residual chlorine and 100 ml and 25 ml alequoits were
filtered for NO3 + NO2 and Chl p analyses, respectively.
In addition, at each station, separate casts of the sample collection bottles were made to
collect water for dissolved oxygen (DO) determination. DO samples were immediately
and directly drawn into 300 ml BOD bottles (displacing 3 volumes 'of water). A YSI
i Model 57 DO meter was used in the field, and 10 percent of the samples were
(, duplicated and preserved in the field with manganese sulfate and alkaline iodide
solutions for subsequent Winkler Titration V (Strickland and Parsons, 1972).
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TIDAL HEIGHT (FEET)
A.
10
s
s
4
2
O
-2
-4
WATER EXCHANGE (MILLION CUBIC FEET /DAY)
100
B.
90
6o
70
60
6o
40
JULY AUGUST SEPTEMBER OCTOBER
Figure 3
TIDAL RANGE (A) AND DAILY WATER EXCHANGE (B).
ARROWS INDICATE SAMPLING DATES.
~-
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FREQUENCY (number) FREQUENCY (percent)
IRA
0- 1710
TIDAL RANGE (feet)
FREQUENCY (number) FREQUENCY (percent)
am
40 45 50 55 60 65 70 75 80 85
WATER EXCHANGE (million cubic feet/day)
~
| ` _
|
. m
Figure 4
FREQUENCY DISTRIBUTION OF TIDAL RANGE (A)
AND DAILY WATER EXCHANGE (B).
8
(' Basin Manning. Bottom contours of Mats Mats Bay were determined by taking 7
transects across the bay. A boat was driven at a uniform velocity along each transect
line and over 100 readings were taken with a depth sounder at equal time increments. A
weighted line was used to calibrate these readings. Approximately 40 additional depth
measurements were also made with the line to quantify depths between transects.
Depth measurements were corrected for tidal height at the time of measurement and
adjusted to use MHW as a reference datum. Isobaths were contoured by linear
interpolation at three foot increments. Near shore isobaths were confirmed with aerial
photographs taken at known tidal height. Areas between isobaths were determined using
a planimeter. Volumes for each 3 foot stratum were calculated by the "average -ends"
method.
Water Exchanae Calculations. Water exchange has been calculated by three methods, but
all based upon the notion of tidal prism and using Mats Mats basin morphometry as
determined in this study. The first, tidal prism exchange, is calculated based upon the
assumption that bay water is exchanged for the incoming ocean water without mixing.
Tidal prism is the volume of water contained in the intertidal zone. Tidal prism
exchange is expressed in percent as the ratio of the tidal prism volume to the mean bay
volume. The second estimate of water exchange assumes that water which enters on the
rising tide is completely mixed with bay water before discharge with the falling tide. .
By this process, each tidal cycle mixes with resident water and gradually dilutes it, but
can never replace all of the original water. This relationship is conveniently expressed
as water residence half -life in terms of tidal cycles:
Tide cycles to replace half of the mean bay volume - (0.693)(avg. tidal range)
(avg. Vol.)
Provided that the assumptions for this calculation are met, 1 half -life discharges 50% of
the average bay volume, 2 half -lives displace 75%, 3 displace 87.5% and so on. The
third estimate is based on tidal excursion. By this method, water is considered to move
by plug flow. The rising tide enters uniformly up the central axis of the bay and the
falling tide discharges as a plug. The tidal excursion estimates are helpful in that the
potential for poor flushing in remote areas of the bay can be assessed.
Drogue Studies. Near - surface water movements were followed with drogues made from
party balloons filled with fresh water (Nixon et al., 1980). The drogues floated with less
than 1/8 inch projecting above water level and with drafts of 6 to 8 inches. Groups of
5 drogues, each group a different color, were deployed at 4 locations within Mats Mats
Bay on the outgoing tide and a group of 20 balloons was released at a single point in
mid- channel near the entrance to the bay during the rising tide.
Drogue locations were noted approximately hourly by approaching each balloon in a boat
and triangulation with a compass to on -shore landmarks. Balloon movement was large
during outgoing tides and it was necessary to periodically capture and rerelease each
balloon group at the original starting positions. Wind speed and direction were estimated
throughout the study.
Two complete tidal cycles, one during a period of minimal tidal exchange and one
during an average tidal prism, were so assayed.
0
Field Data: Temoerature. Salinity. Secchi depth. The vertical distribution of
t! temperature and salinity was determined at each station with a YSI model 33 S -C -T
meter. The probe was lowered through the water column and temperature and salinity
were recorded at 1 m intervals from the surface to 12 m. Secchi depth was measured on
the shady side of the boat.
Nutrients: NO. + NQ2, NH4. TKN. TP. Nutrients were determined by an independent
testing lab. Samples for NO3 + NO2 - N were filtered through prewashed 0.45 um
membrane filters and those for NH4 - N and TKN were analyzed on unfiltered
fractions. NO3 + NO2 - N were analyzed by an automated cadmium reduction method,
NH4 - N by an automated phenate method and TKN by a micro- Kjeldahl method with
phenate finish (APHA 1985).
Total phosphorus was assessed on unfiltered seawater samples following persulfate
digestion by the ascorbic acid /molybdenum blue method (APHA 1985). Samples were
acidified to pH I with H2SO4 and deep frozen until analysis.
Fecal Coliform. Fecal Coliform was determined by the multiple tube fermentation
technique by an independent testing laboratory and results were presented in terms of
Most Probable Number (MPN) (APHA 1985). This technique is chosen to provide
continuity with past sampling efforts.
Chlorophyll a. Samples were filtered for Chl a following vigorous shaking of the
seawater samples by filtering approximately 25 ml (as needed) through 4.5 cm Gelman
GF /C glass fiber filter paper and spiked with 1 ml of magnesium carbonate suspension.
The magnesium carbonate suspension will be prepared by adding 1 g of finely
powdered, reagent grade magnesium carbonate plus 3 g of reagent grade sodium chloride
to 100 ml of distilled water in a stoppered flask. The filter paper was desiccated and
deep frozen until analyses. Chl a and phaeo - pigments were analyzed by fluorometer as
described by Holm- Hansen et al (1983).
Air Temperature, Wind Sneed. Tide. Air temperature and wind speed was determined
from instruments located at Port Ludlow Harbormaster Restaurant Lobby immediately
prior to sample collection. Tide conditions for Port Ludlow were determined from a
Seattle tide chart (NOAA) corrected for height by a ratio of 0.88 and corrected for time
by subtracting 27 minutes to determine high tides and subtracting 18 minutes for low
tides. Mats Mats Bay tides are considered to be well represented by Port Ludlow tides.
Statistics, Significance was assessed with a Student's t test at a 95% confidence interval.
RESULTS AND DISCUSSION
Data Ouality Assurance
Data quality is described by five basic points: (1) Accuracy. Data accuracy has been
determined by matrix spike addition for nutrients and salinity. Results (Table 1)
1 d indicate that accuracy has ranged from 89.1% to 107.3%. EPA guidelines for RCRA
facility investigations consider matrix spike recovery in the range of 75% to 125%
acceptable. (2) Precision. Precision describes the repeatability of a measurement. For
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example, if a sample is reanalyzed several times and the results are very close, then a
high level of precision has been achieved. The relative percent difference (RPD)
between duplicate samples is a measure of precision and has been used for this study.
Measured RPD (Table 1) have ranged from 0.4% to 15.7% for nutrients and salinity but
were in excess of 25% for Chl 1i and for phaeophytin. EPA guidelines indicate that for
data to be of good quality the RPD should be less than 20%. (3) Completeness. The
available data is considered to be complete if it is sufficient to describe the environment
according to plan. The data set presented here is complete enough, both in terms of
numbers of stations and number of sample episodes, to assess environmental impacts of
the sewage effluent discharge. (4) Representativeness. Representativeness describes how
well the data reflect actual site conditions and is primarily influenced by the sampling
program and analytical methodology. Mats Mau Bay samples have been collected during
the summer season and during the last half of ebb tide on days with minimal tidal
exchange. Thus, with respect to water flushing, worst case conditions have been
targeted and the data is evaluated in that context. (5) Comparability. Data which has
been collected and analyzed with standardized methods may be cross compared with
confidence. Methods used were standard for oceanographic investigations.
In summary, data quality is deemed wholly satisfactory for the purposes of this
evaluation.
Basin Morphometry
Mats Mats Bay is small heart- shaped basin of about 133 acres._ Maximum and average
depths at the mean tidal level are 24.7 and 9.9 feet (Table 2). Area and volume are
indicated in Table 3. The deep hole is located on the eastern edge of the basin and close
to the channel entrance (Figure 2). The channel is long and narrow, about 3,300 feet by
300 feet and also relatively deep, with maximum and mean depths of 15.7 and 9.5 feet
respectively. The volume of Mats Mau Bay plus the channel is 57.5 million cubic feet
at mean tide, of which about 77% is within the bay and 23% in the channel (Table 3).
The intertidal volume is very large with respect to the basin volume (Figure 5).
Approximately 65% of the basin water is discharged as the tide drops from mean high to
mean low water.
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DEPTH (feet)
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DEPTH (feet)
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20 40 60
VOLUME (million cubic feet)
URW
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10 20 30 40 50 60 70 80 90 100
PERCENT VOLUME
Figure 5
DEPTH VOLUME (A) AND
DEPTH PERCENT VOLUME (B) CURVES.
15
t Water Exchange
The average ebb tide, a 6.7 foot drop from mean high to mean low water, discharges
65% of the mean tide volume which indicates that bay water is exchanged with ocean
water about 1.3 times per day. A slightly more conservative approach assumes complete
mixing within the bay and indicates that the water half -life is on average 0.32 d. Thus,
about 50% of the water is replaced in 0.32 d, 75% in 0.64 d and about 87.5% each 0.96
d. The 5% minimal tidal exchange is 40 to 45 million cubic feet per day (Figure 4B)
and results in a water half -life of 0.55 d. Thus, even during periods of minimal
flushing, considerable water exchange occurs in Mau Mats Bay.
Water exchange is not simply controlled by tidal action, however. Some water washed
out of the bay may reenter on the rising tide, effectively reducing the extent of
flushing. On the other hand, fresh water inflow may serve to increase the volume of
water flushed from the bay. Circulation within Puget Sound, for example, is strongly
controlled by the volume of river inflow. Because the sound is not getting deeper, the
fresh water volume must exit, and also, because the sound is not getting less salty, ocean
ll water must enter to maintain the salt balance. The volume of ocean water necessary to
maintain the salt balance is approximately 10 to 20 times the fresh water volume and
thus density driven salt balance circulation exceeds the circulation set up by the tidal
prism. For Mats Mats Bay however, the role of water reentry and that of fresh water.
input are thought to be unimportant as described below.
The channel from Mats Mats Bay opens to Puget Sound between Olele and Basalt Points.
Effectively, the channel opening is on a promontory which extends into the Admiralty
Inlet portion of Puget Sound (Figure 1). This region of Puget Sound is known to be
vigorously mixed with current velocities on the order of 0.3 knots (Mofield and Larsen,
1984). Adjacent to Mats Mats Bay, prevailing currents flow northward, possibly on both
ebb and flood tides, and mixing depth is generally on the order of 50 m (Harper -Owes,
1988). Thus, even in worst case conditions, water from the bay is likely swept from the
channel mouth with only a small fraction available to re -enter the bay.
Creek input to Mats Mats Bay was negligible during the 1989 study period. Combined
flow from the three freshwater creeks was 0.32 t 0.11 cfs and represented a total inflow
of about 31 million gallons. In contrast, based on data from Port Townsend, estimated
evaporation from Mats Mats Bay during the same 152 day period was 20 inches, or 73
16
million gallons. Evaporation apparently exceeded inflow as confirmed by measurements
t
which showed that the background station in Admiralty Inlet (Sta. I) was slightly, but
not statistically, less saline than Mats Mats Bay stations. Water and salt mass balance
calculations can be combined to evaluate the extent of water exchange. Such estimates
are extremely sensitive to salinity and now data and were not meaningful for this study.
The small volume of freshwater inflow and the negligible density difference between
Mats Mau Bay and Admiralty Inlet are not perceived to have a strong influence on Mats
Mats Bay circulation. Therefore, tidal prism and half -life calculation are thought to
represent good estimates of water exchange.
The areal extent of bay flushing has been estimated with the use of a cumulative volume
curve. The curve was constructed by division of the bay into sections along its central
axis from the head of the bay to the mouth of the channel (Figure 6A). The water
volume in each of these sections was then determined and cumulative mean high and
mean low water plotted as a function of distance from the bayhead (Figure 6B). The
slope of the cumulative volume lines gives information about the basin configuration
along the central axis. Where the slope is steep,, the basin has a large cross sectional area
due to width or depth, and where flatter, the basin has a smaller cross sectional area.
Figure 6B shows that most of the volume is contained in the bay itself between 800 and
2,000 feet from the bay head as indicated by the steep slope. The channel, 2,509 to
5,855 feet from the bay head, is relatively deep but very narrow and thus contains a
small volume. At mean high tide the bay contains 77% and the channel 23% of the total
bay plus channel volume.
The cumulative volume curve can be used to estimate the distance a parcel of water may
move with a rising or falling tide. The key assumption is that tidal currents move by
plug flow along the central axis rather than mixing with the resident water. The graph
indicates that on the average ebb tide all water located beyond 1,500 feet from the bay
head is discharged. The example tidal excursion plotted (Figure 6B) indicates that the
average ebb will move a parcel of water from 1,100 feet to abut the 1,900 feet from the
bay head. Thus, a conclusion is that water within the 1,537 foot boundary as drawn on
Figure 6A is potentially more stagnant than water beyond.
In order to more fully evaluate if water from all regions of the bay are uniformly
flushed, two drogue studies were performed. To be consistent with the worst case
4
17
11�'
A. '
CENTRAL AXIS
4.431'• • .
.. s1�7• leas•:.
• - s4o6•
• • + + e t ' �' •a • DISTANCE
FROM
HEAD OF SAY
a.
`2509' .
• • ,� 15378
062'
573'
HEAD OF BAY `
VOLUME (million cubic feet)
80
B.
60
40
20
0
0
MHW
TIDAL EXCURSION
MLW
1000 2000 3000 4000 5000 6000
DISTANCE FROM THE HEAD OF THE BAY (feet)
Figure 6
DISTANCE FROM HEAD OF BAY IS SEGMENTED (A)
TO PRODUCE A TIDAL EXCURSION GRAPH (B)
�8
flushing analysis approach of this evaluation, one drogue study was performed during a
minimal tidal exchange, while the other during an average tidal cycle.
Drogue paths are displayed for ebb and flood tides which occurred during periods with
low and average tide range (Figures 7 -10). Predominant winds were from the north, but
were very light, generally 2 to 5 knots. Surface currents moved in response to the wind
and drogue movement was generally southward, into the bay, regardless of tidal
direction. In some instances, balloons beached, an indicator of surface water
downwelling. In other cases the balloons moved counterclockwise at the head of the
bay. The picture which emerges is that the light winds which prevail during summer
and fall serve to hold floating and near - surface objects within the bay despite the great
tidal flushing rate.
Water column stability and small scale mixing (dispersion) are additional factors which
exert important influences on water exchange. Water column stability occurs when less,
dense water overlies denser water. Oceanographic convention expresses density (p) in
terms of sigma t (at):
at =(p - l)x 103
Measured salinity and temperature have been used to calculate at from Knauss (1978).
Stability (E) is an indicator of the work required to move a parcel of denser water some
distance upward into a lighter layer, and is calculated as the change in potential density
with depth:
E =( -1 1p) x (tat /8z) x (10-3)
Mats Mats Bay had stable density stratification as indicated by greater at at depth during
sample occasions in July, August, and September (Table 4). Stability during this period
was high, in excess of 1,000 10-8 m'1, which indicates the existence of a pycnocline, a
density gradient (Fischer, 1986). Thus, during this period, the bay was not mixed from
top to bottom. Complete vertical mixing was implicated during the October sampling by
negative values of E.
Temperature distributions indicate that the upper mixed layer was 7 to 8 feet deep. The
extent of mixing within this layer is determined by the rate which drogues separated
from one another. Random walk calculation (Fischer, 1988) based on the drogue data
19
a
TIDE
(lost)
DROGUE CHECK TIMES
12
.j
:. 4 ' • '
•r. 3 ',•
TIME SOUNDINGS IN FEET
1
Figure 7
DROGUE STUDY
EBB TIDE
MINIMAL TIDAL EXCHANGE
N
• as
0 Soo 1 000
-° ='•
,2
_
SCALE FEET
-ti..
' •
..•
••
KEY
. `'�
''� . •
1O -DROGUE
_•
"�
.•
~•
RELEASE
•
:••
:',
POINT
e
• •�-
1S
• . ,'
` ti
';� '
•.
ti�
.
3TO 6 KNOTS
3
PREVAILING
•
.
WIND
2 �lb
.
DROGUE CHECK TIMES
12
.j
:. 4 ' • '
•r. 3 ',•
TIME SOUNDINGS IN FEET
1
Figure 7
DROGUE STUDY
EBB TIDE
MINIMAL TIDAL EXCHANGE
0 500 1000 : ,. •' +- 2 15 C
.SCALE FEET ' •';� 9 1, ; "` :•: ,
• = • ' KEY '
' '' ; • • 10 'DROGUE
•,� 1 RELEASE
• 6 .. POINT
. •� f 5 TO O KNOT
C PREVAILING
e WIND
:•ih d�
DROGUE CHECK TIMES r • '
•s 15 -
12
TIDE
(test) 8
TIME
• SOUNDINGS IN FEET
Figure 8
DROGUE STUDY
FLOOD TIDE
MINIMAL TIDAL EXCHANGE
TIDE
(feet,
a
1 r
O.. 500 1000 2 15
SCALE FEET -
• ; . • KEY.
•
(j)-DROGUE
• • . � , _ RELEASE
• g .;�'• .• •.a
POINT
' •� 2 O TO 3 KNOTS
PREVAILING
• WEND
3 .
DROQUE CHECK TIMES •:.
•.. 15 �
12 '
O 4 4 12 10 20 24 ,• .'•
TIME ; • r ,
• SOUNDINGS IN FEET
Figure 9
DROGUE STUDY
EBB TIDE
AVERAGE TIDAL EXCHANGE
i Y
1
Figure 10
DROGUE STUDY
FLOOD TIDE
AVERAGE TIDAL EXCHANGE
. .f
•s.
15
0 S00 1000
12
~•'�"
SCALE FEET
�• • •
• i•
• • + M�
•
...•
.•
KEY
' •` •
•' � '
' ;�
0 'DROGUE
•
•
. •
RELEASE
•
POINT
:s
' • �:_�_' Oi, • '•
• •'
15
• .
O TO 2 KNOTS
_
• •
•
,� '�
PREVAILING
WINDS
'
NORTHERLY.
FIRST 3
• :;,
::
MEASUREMENTS
DROGUE CHECK TIMES
SOUTHERLY.
LAST 3
'•
MEASUREMENTS
•
,
•''
TIDE
(feet)
12
.
TIME
•.
�� '.
•
SOUNDINGS IN FEET
Figure 10
DROGUE STUDY
FLOOD TIDE
AVERAGE TIDAL EXCHANGE
} a
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indicate that horizontal dispersion was on the order of 104 cm2 /s which is relatively
small but typical for bodies of water the size of Mats Mats Bay (Chapra and Reckow,
1983).
The channel is vertically well mixed. Tidal inflow proceeds uniformly throughout the
channel. Peak observed inflow rate during the average tidal exchange was 1.3 feet per
second from the top to within 1 foot of the bottom. During outflow, peak flow was 1.4
feet per second two feet deep and dropped linearly to about 0.4 feet per second just
above the bottom. Flow through the channel apparently moves as a plug.
Available Light
Light, rather than nutrients, controls the rate of phytoplankton growth for much of the
year in Puget sound waters (Winter rd g_l 1975). Available light for phytoplankton
photosynthesis depends upon the amount of incident solar radiation as well as water
clarity. Average daily solar radiation (It) has been obtained from Astoria, Oregon (1953-
1968 average) and is considered to be more representative of Mats Mau Bay than data
from Sea -Tac airport. These data show that light levels vary seasonably from a peak of
about 526 ly /d in July to a minimum of 77 ly /d in December. Solar radiation is
expressed in langleys per day (ly /d, a heat measurement of 1 gram calorie per square
centimeter of surface). Strickland (1958) has demonstrated that about one half of It is
available for phytoplankton growth:
1/2 It - Io
This available light is further reduced by selective adsorption and scattering as it
penetrates the water column. The reduction is described by Beer's Law, which can be
rearranged to calculate the average light available for phytoplankton photosynthesis (I):
I - (Io /kz)(1 —e-kz)
where, z is the depth of the mixed larger and k is the light extinction coefficient. The
light extinction coefficient is obtained from secchi depth:
i k - 1.44 /secchi depth
25
Secchi depth, which is an indicator of water clarity, has been measured to range from
2.2 m to >5.1 m (Table 5). For other months of the year secchi depth has been
conservatively estimated to be 3 m. Algal blooms potentially develop when the average
available light in the water column (I) exceeds 40 ly /d. Ambient light levels have been
calculated for the mid bay (Station 3) assuming that the mixed depth extends to the
bottom. The results indicate that light is sufficient to support algal blooms between the
months of March through September but that the winter months of October through
February have shorter days and low sun angle and, thus, too little ambient light to
support rapid phytoplankton growth.
Oceanographic convention describes critical depth (Dr) as the depth where
photosynthetic oxygen production in the water column is equal to the oxygen consumed
by water column respiration. The light level at the critical depth is on the order of 5.0
ly /d and thus:
Dcr - I6/(5.0)k
The calculated critical depth in all portions of Mats Mats Bay ranged from 30 m to 161
m, always well in excess of the water depth, and thus water column oxygen production
is expected to exceed oxygen utilization within the bay all year long. A conclusion is
that oxygen depletion is not anticipated to occur even at depth in the water column.
Oxygen demand of the sediments however is likely to periodically result in reduced
oxygen levels near the sediment -water interface.
Temperature
Mats Mats Bay remained cool throughout the summer, 14.2 t 1.1 'C near the surface and
12.9 t 1.0 'C at depth, which is not significantly warmer than surface waters of
Admiralty Inlet (Sta. 1). Significant temperature stratification did exist within Mats
Mats Bay. Distinct thermoclines existed at depths of 8 and 9 feet during the July and
August surveys, but temperatures were uniform from top to bottom in September and
October. Water which entered and exited through the channel was the same temperature
as Mau Mats Bay bottom water and was significantly cooler than water above the
thermocline. This information indicates that water exchange involves water beneath the
thermocline to a larger degree than water above the thermocline. It is interesting to note
that the minimum temperature necessary for oyster spawning is 18 °C, considerably
Table 5. Water quality indicators for Mats Katz Bay during the summer of 1989. Station, locations are as
indicated on Figure 2. T and B refer to top and bottom and I and 0 to inflow and outflow samples, respectively.
t STANDARDS > 2 > 7.0 14 < 10
or >(bkg -0.2'
27
NITRATE
TOTAL
TOTAL SOLUBLE
.
SECCHI
DISSOLVED
♦
UJELDAHL
PH09-
PH09-
FECAL
PHAEO-
DATE
STA
DEPTH
TEMP SALINITY
OXYGEN
AMMONIA
NITRITE
NITROGEN
PHORUS
PHORUS COLIFORM
CHL a
PHYTIN
■ deg.0
ppt
mg/L
ug NA
ug N/L
ug NA
ug P/L
ug P /L.NPN /100m1 ug /L
ug /L
11- Jun -89
IT
4.3
13.0
29.10
10.4
52
95
467
76
<
2
8.20
1.50
1B
11.8
30.00
8.4
58
143
208
75
<
2
2.30
0.40
10- Jul -89
2I
> 3.2
10.8
30.43
10.2
28
159
256
61
44
<
2
7.00
< 0.10
20
> 3.8
13.0
30.38
11.9
69
67
346
53
40
2
3.90
0.20
3T
2.2
14.2
30.34
12.6
50
63
< 100
Be
38
11
5.50
1.30
3B
11.8
30.43
7.2
123
51
175
66
47
<
2
3.60
0.80
4
0.7
13.7
30.29
12.8
23
70
211
61
40
<
2
13.40
3.19
IT
5.8
11.9
29.82
10.1
55
140
< 100
63
<
2
3.50
< 0.10
1B
11.7
29.89
6.6
58
168
< 100
73
<
2
1.70
< 0.10
07- Aug -89
2I
> 4.7
12.2
31.30
12
174
354
87
57
<
2
5.05
< 0.10
20
> 4.8
12.3
31.70
8.4
11
174
462
84
59
<
2
3.19
0.32
3T
3.0
15.3
31.12
11.6
< 10
47
286
74
32
<
2
11.87
0.59
3B
13.0
31.23
10.0
< 10
71
502
81
69
2
14.97
< 0.10
4
> 1.6
15.5
31.52
12.6
12
59
585
80
40
<
2
10.06
0.50
IT
8.8
14.5
30.69
9.9
46
160
584
78
49
4
6.30
< 0.10
1B
31.41
6.9
29
211
327
91
66
<
2
3.00
< 0.10
06- Sep -89
2I
> 4.9
12.9
30.98
7.5
20
163
329
79
75
-<
2
5.48
< 0.10
20
> 4.8
15.8
30.69
9.8
23
194
< 100
79
78
:<
2
4.11
< 0.10
3T
3.7
14.9
30.65
9.0
13
168
256
81
72
5
7.40
< 0.10
3B
14.5
30.98
7.5
23
168
< 100
88
72
<
2
5.86
< 0.10
4
> 2.8
13.6
30.32
7.6
26
164
199
86
71
<
2
6.51
< 0.10
IT
7.6
17.0
31.23
7.5
25
154
< 100
83
79
<
2
6.00
< 0.10
18
13.0
31.16
5.0
35
183
< 100
83
84
<
2
5.00
< 0.10
07- Sep-89
2I1
> 4.8
13.0
30.54
9.5
23
195
284
81
77
<
2
4.04
0.67
2I2
> 5.0
13.0
30.29
9.9
24
194
< 100
82
76
<
2
7.26
< 0.10
201
> 4.7
13.2
30.87
9.6
17
214
148
81
76
<
2
2.95
< 0.10
202
> 4.7
13.8
30.32
10.1
27
201
< 100
79
78
`<
2
2.65
0.60
29- Sep-89
2I1
3.7
12.5
30.11
9.5
45
228
272
.93
57
<
2
1.74
< 0.10
2I2
> 5.1
12.5
30.93
9.3
70
506
216
145
57
<
2
2.00
0.10
201
> 5.1
12.3
31.49
9.7
88
132
445
77
53
6
2.19
0.11
202
> 3.5
12.6
30.50
11.0
71
119
173
93
56
4
3.24
< 0.10
05- Oct -89
2I
5.1
12.0
30.49
9.2
63
223
246
86
53
4
t 0.10
2.29
20
> 5.0
11.7
30.42
8.5
100
231
490
91
57
<
2
0.45
t 0.10
3T
4.3
12.5
30.49
8.0
99
209
325
90
47
2
0.43
0.17
3B
12.4
30.28
5.1
77
192
390
91
57
<
2
0.37
0.94
4
> 1.9
12.2
30.45
6.3
103
206
205
93
53
7
1.34
< 0.10
IT
7.9
12.5
29.82
7.0
67
178
557
77
55
<
2
0.80
0.30
1B
12.0
30.56
5.8
63
225
557
92
67
2 < 0.10
< 0.10
AVERAGE
2I
4.6
12.4
30.63
8.1
36
230
257
89
62
2
4.08
0.45
20
4.8
13.0
30.85
9.6
50
214
288
87
62
2
3.26
0.14
3T
3.3
14.2
30.65
10.3
43
122
242
76
47
4
6.30
0.54
3B
12.9
30.73
7.5
58
121
292
82
61
2
6.20
0.49
4
1.8
13.8
30.65
9.8
41
125
300
SO
51
3
7.83
0.97
IT
7.5
14.0
30.39
8.6
48
158
335
75
46
2
4.15
0.15
1B
9.2
30.76
6.3
46
197
271
85
54
2
2.45
0.10
t STANDARDS > 2 > 7.0 14 < 10
or >(bkg -0.2'
27
1
warmer than was achieved in Mau Mats Bay during the study period. Oysters may
maintain a natural population if waters are warm enough to support spawning every 10
years or so. Introduction of oyster spat by man will also permit oyster rearing at the
observed temperatures.
Dissolved Oxvaen
Dissolved oxygen (DO) concentrations within Mats Mats Bay were generally high, on
average about 150% supersaturated and not significantly different from'Admiralty Inlet
values. In October, however, DO in bottom water (Sta. 3B) was 5.1 mg/L and in the
northern station (Sta. 4) was 6.3 mg /L, both less than the Class AA water quality
standard of 7.0 mg /L. Dissolved oxygen was also low offshore, (Sta. 1); 7.0 mg /L in
surface water and 5.8 mg/L at depth (Table 5). Fall upwelling is characteristic in
Admiralty Inlet and results in depressed DO levels. Because offshore water represents
the source of water to Mats Mats Bay, the upwelling is partially responsible for the low
DO levels. Water quality standards account for this and when natural conditions, such as
upwelling, cause DO to be depressed near or below 7.0 mg /L, then man caused activities
may further degrade DO by 0.2 mg /L. However, in Mats Mats Bay the DO was as
much as 1.9 mg /L less than the background. It is not possible to accurately predict the
extent that man's activities reduced DO in Mats Mats Bay. Man's influence includes
such sources as the respiration of herring stored in net pens and the increase in oxygen
demand of sediments as a result of the introduction of organic materials to the bay. The
respiration of herring is considered to be very similar to that of their Atlantic allies, the
menhaden, at about 0.1% mg DO /g wet weight /h when relatively inactive and not
feeding (Durbin et al 1981). Based on 2.7 million herring per year, 14 d holding time,
30 g per fish and the above oxygen consumption rate, the fish consume 300,000 mg
DO /h or about 0.1% of the incoming DO. The oxygen demand of the herring operation
is thus not perceived to be a problem for Mats Mats Bay.
Nutrients
The nutrients of most concern for Mats Mats Bay are nitrogen (N) and phosphorus (P),
because, when given sufficient light, one of these elements may potentially limit the
• growth rate of phytoplankton. The ratio of N:P in marine phytoplankton is generally on
the order of 10:1. Water which contains a ratio less than 10:1 has a relative shortage of
N and is said to be N limiting for phytoplankton growth. Mats Mats Bay waters
28
t
consistently had TN:TP and soluable N:soluable P ratios of approximately 5:1 and 4:1,
respectively, indicating that N, rather than P, was in shortest supply for phytoplankton
growth. Ratios of N:P within Mats Mats Bay did not differ significantly from station to
station or from those of Admiralty Inlet.
Despite indications of N limitation, the absolute level of dissolved inorganic nitrogen
(DIN, the sum of nitrate + ammonia; the primary forms available for phytoplankton
uptake) remained high (Table 5). Even during August when peak phytoplankton
concentrations were observed, concentrations of DIN remained in excess of 47 pg N /L.
Eppley et al. (1969) has shown that many coastal phytoplankters may grow at nearly
maximal growth rates when DIN exceeds 15 pg N /L. Thus, with available nitrogen
always available in excess of demand, nutrient limitation by N or P is not thought to
have occurred.
The sources of nutrients to Mats Mats Bay may be evaluated by mass balance methods
(Table 6). These data suggest that marine input of nutrients from water outside the bay
is by far the most important source. Creek TN levels on average were the same as those
flowing into the bay via the channel, 472 versus 480 pg N/L but creek TP values were a
bit greater, 141 versus 89 pg P/L (Table 7). But because creek flow was about 1900
times less than tidal inflow, the mass contribution from the creeks is considered
negligible. Absolute concentrations of nitrogen in the three creeks are considered to be
moderately low. The flow weighted DIN was 239 pg N/L which can be contrasted to a
median DIN of 687 pg N/L for 44 streams in the Seattle -King County region (Metro
1988). In contrast, TP was rather concentrated in the Mats Mats Bay creeks. The flow
weighted TP concentration was 141 pg P/L about 2.4 times greater than the Seattle -King
County median of 58 pg P/L (Metro 1988).
A third possible source of nutrients during the study period, internal loading, can be
evaluated with the mass balance approach. Internal loading, in this case, lumps together
all non -point nutrient sources, and does not include inflow from the channel or the three
creeks. Notably, these sources may include, sediment release, groundwater and septage
input, boater activity and the herring net pen operation. Internal loading is found by
difference of inflow to the bay minus outflow and thus is subject to large error. It is
• stressed that these results are not statistically significant, yet do yield insight on
estuarine processes. Two tentative conclusions may be drawn from results in Table 6.
TP apparently sedimented during the summer, but at the onset of fall turnover in
29
1
QfO 1
O .0 woo -'VA: A:
Y'f W 9 G! .
s m 019 .o
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m a m Pf m l N I
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.t.
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i
m 1
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= 1�ir,Ob ODftIV
esi.+omma�o
47
40-4 m� N! N
' -m w 1N 1�
1 !•r N .y
40111N1000 to
i�
l-oe 1�.•+b ON
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� 'i - I
October, net release to the water column occurred. Sediment during July and August
consumed approximately 4% to I I% of the P which entered the Bay, and in October
sediment P release contributed about 6% of the P load. This process is consistent with
known mechanisms governing P solubility. When low or no oxygen is present, sediment
iron is reduced to soluble ferrous (II) form with simultaneous release of P with which it
had coprecipitated. However, with oxygen present, coprecipitation of iron and P occur.
Measured water column DO was always sufficient to cause coprecipitation of iron and P,
however, the inference is that anoxic conditions developed at and below the sediment
surface throughout the study period and in October sediment P was mobilized into the
water column by complete vertical mixing. TN was, on average, generated in the bay,
but no consistent trends were observed.
In summary, nutrients are in abundant supply in Mats Mats Bay and are not perceived to
limit the growth of phytoplankton. Inflow of offshore water represents the single most
important source of nutrients to Mats Mats Bay because of the large volume exchanged.
Creek water may have moderately elevated P concentrations, but flow is so small that
changes in bay nutrient concentration or ratios is not likely to alter phytoplankton
growth or species composition. Bay sediments themselves may seasonally act to scavenge
or release important levels of P.
Phvtoolankton Abundance
Quantification of water column chlorophyll g (chi lil is a frequently used indicator of
phytoplankton abundance. As for total nutrients, chi g concentrations did not differ
significantly between the offshore station and Mats Mats Bay stations. No established
water quality standard exists for chi g but frequently used guideline suggests that chi a
concentration in excess of 10 pg /L may constitute an aesthetic nuisance and possibly
result in seriously depressed oxygen levels. In Mats Mats Bay, average chi g levels were
3.3 to 7.8 pg /L, but the 10 pg /L guideline was exceeded in 4 of 28 samples (14%), with
a peak concentration of 14.97 pg /L. These concentrations are not considered alarming.
Greater yet chi g concentrations were noted in nearby Port Ludlow during the same
period (HLA 1989). However, high concentrations of chi g during 1984 and 1989 in
Port Ludlow was not attributed to man's influences, but to natural variation in
phytoplankton growth and death rates.
32
i
These same influences, namely available light, zooplankton grazing and pycnocline
development, may have been such to permit greater than normal chi It accumulation in
Mats Mats Bay as well.
Mass balance calculation (Table b) indicates that about 30% less chi a washed out of
Mats Mats Bay than entered. Two theories, which are not mutually exclusive, may
account for this. Either phytoplankton death exceeded growth because of zooplankton
and oyster feeding or the phytoplankton were able to adjust their vertical placement in
the water column to avoid washout.
Paralytic shellfish poisoning may occur when toxic phytoplankton species are present,
sometimes visible as red tides. Shellfish toxin levels are routinely monitored in Mats
Mats Bay and at Olele and Klas rocks near the channel opening by DSHS. These results
indicate that dangerous levels of toxin occasionally occur (DSHS 1988).
Water Column Fe a] Coliform Bacteria
Water column fecal coliform bacteria were not abundant in Mats Mats Bay (Table 5).
The maximum detected concentration was 11 MPN/ 100 mi but 19 of 28 samples
contained less than the detection limit of 2 MPN /100 mi. The geometric mean
concentration was less than 2.5 MPN /100 ml, within the 14 MPN /100 ml geometric
mean limit imposed on Class AA Waters (WAC 173 - 210 -045). Low fecal coliform levels
in Mats Mats Bay have been confirmed by other studies. A suite of 13 samples collected
during May through July 1987 (Harper -Owes, 1988) had a geometric mean concentration
of 4 MPN /100 ml. Four stations sampled 12 to 14 times each by Rubida (1989) had
geometric means which ranged from 0.4 to 2.0 MPN /100 ml.
Despite low fecal coliform concentrations in bay water, the three creeks exceeded Class
AA water quality standards. These standards, for Class AA freshwaters, state that fecal
coliform organisms shall not exceed a geometric mean of 43 organisms /100 ml with not
more than 10% of the samples in excess of 100 organisms /100 ml. Ten samples collected
from the three creeks had a geometric mean of 121 MPN /100 ml and the estimated
upper 10% was 920 MPN /100 ml. All three creeks exhibited violations of the standards.
As contrast, 44 creeks in the Seattle -King County area displayed a geometric mean of
188 MPN /100 ml, also in violation of standards. Rubida (1989) measured fecal coliform
in the same 3 creeks during 1988 and found substantially lower concentrations; of 24
33
samples collected, no violations of water quality standards were observed. Geometric
means in 1988 were found to vary from 22.5 to 43.7 MPN 1100 ml. No significant
changes in land use, boater pressure or increase in groundwater table are thought to have
occurred between 1988 and 1989 and thus it is difficult to reconcile the great increase in
fecal coliform data. However, because from a mass balance perspective the creeks
represent a tremendous source of bacteria to the bay (Table 6) and because the creeks
drain to shorelines from which oysters are harvested, the observed freshwater bacterial
levels must be considered as a potential threat to human health.
Shellfish Fecal Coliform Bacteria
Oysters filter tremendous volumes of water each day and in so doing, concentrate
available algae, bacteria and pathogenic microorganisms. Fecal coliform bacteria are
among the organisms concentrated by oysters. Fecal coliform bacteria are not
intrinsically hazardous to human health but are a sensitive indicator of fecal
contamination. Thus, when.fecal coliform bacteria are detected, in water or oyster
tissue, infectious disease microorganisms such as salmonella, typhoid or cholera may also
be present if infected individuals are in the catchment.
Freshwater input typically represents a large source of fecal contamination to marine
systems and, because freshwater tends to float, highest contamination levels often exist
at the 'surface. Because oysters reside in the intertidal zone, they are in an area of high
exposure to surface waters. As discussed previously, bay water had essentially
undetectable fecal coliform bacterial concentrations, but the three inflow creeks
contained relatively high concentrations.
The Food and Drug Administration has promulgated a guideline of 230 fecal coliform
organisms per 100 ml of shellfish tissue 1, which applies to commercial sales. Oysters in
Mats Mats Bay exceeded this guideline in 5 of 6 samples, having a geometric mean of
333 MPN /100 ml and a maximum of 673 MPN /100 ml (Table 8). Samples collected
immediately adjacent to inflow creeks displayed greater concentrations of fecal coliform
than did oysters from a location distant from the creeks; with geometric means of 552
versus 259 organisms/ 100 ml. Prior data (Jefferson County Department of Health, Pers.
k Comm.) include a shellfish sample from June 1985 with 20 MPN /100 ml and three
during 1987 which showed levels of 20, 78 and 1300 MPN /100 ml. Thus, fecal
contamination of oysters is indicated, and likely via the inflow creeks.
34
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4. No significant differences in water column temperature, dissolved oxygen,
nutrients, chl I or fecal coliform bacteria were noted between Mats Mats Bay and
Admiralty Inlet. This apparent uniformity is attributed to the high extent of
water exchange.
S. Fecal coliform levels were quite low in bay water, but were in excess of
regulatory standards in creek water and in oyster tissue.
37
I J
i'
ti
( REFERENCES
APHA. 1985. Standard methods for the examination of water and wastewater. 16th Ed.
American Public Health Association. 1268 pp.
Chapra, S. and K. Reckow. 1983. Engineering Approaches for Lake Management. Vol.
2: Mechanistic Modeling, Butterworth, Boston, 492pp.
Collias, E.E., N. McGary, and C.A. Barnes. 1974. Atlas of physical and chemical
properties of Puget Sound and its approaches. University of Washington Press.
Washington Sea Grant Publication. 235pp.
Determan, T.A., B.M. Carey, W.H.. Chamberlain and D.E. Norton. 1985. Sources
affecting the sanitary conditions of water and shellfish in Minter Bay and Barley lagoon.
WDOE Report No. 84 -10. 186 pp.
DSHS. 1988. Red Tide Report 1985 -1987. Department of Social and Health Services,
Shellfish Section.
Durbin, E.G., A.G. Durbin, P. Verity, and T. Smayda. 1981. Voluntary swimming
speeds and respiration rates of a filterfeeding planktivore, the Atlantic menhaden,
Brevoortia tvrannus. Fish. Bull. 78:877 -886.
Eppley, R.W., J.N. Rogers and J.J. McCarthy. 1969. Half saturation constants for uptake
of nitrate and ammonium by marine phytoplankton. Liminol. Oceanogr. I4:912 -920.
Fischer, H. et al. 1979. Mixing in Inland and Coastal Waters. Academic Press. Boston,
483pp.
Harper -Owes. 1985. Water Quality Investigation of Port Ludlow. Final Report.
Prepared for Pope Resources. 126pp.
Harper -Owes. 1986. Port Ludlow Circulation Studies. Final Report. Prepared for Pope
Resources. 81 pp + Appendices.
HLA. 1989. Water Quality Conditions of Port. Ludlow Bay. Prepared for WDOE in
support of NPDES Permit No. WA.002120.0.
Holm- Hansen, O. et al. 1965. J. Conseil, Conseil Perm. Intern. Exploration Mer. 30:3.
Knauss, J.A. 1978. Introduction to Physical Oceanography. Prentice -Hall, Inc. 338pp.
Metro. 1988. Quality of local lakes and streams: 1986 -1987 status report. Publication
167.
Mof jeld, H.O. and L.H. Larsen. 1984. Tides and tidal currents of the inland waters of
Western Washington. NOAA Tech Memo. ERL PMEL -56. 52pp.
Nixon, S.W., Alonso, D. Pilson, M.E.Q. and B.A. Buckley. 1980. Turbulent mixing in
1 aquatic microcosms. In: Ed. J.P. Geisy Microcosms in Ecological Research.
38
c�
w
t;
Rubida, P. 1989. Jefferson County Ambient Water Quality Report. Final Report.
Jefferson County Water Quality, Planning and Building Department.
Seabloom, R.W., G. Plews and F. Cox. 1989. Puget Sound Boater and Marina Study.
Draft Report, Washington State Department of Social and Health Services. 59pp.
Strickland, J.D.H. & T.R. Parsons. 1972. A practical handbook of seawater analysis.
Second Edition. Fish. Res. Bd. Can. Bull. 172. 310 pp.
USDA and SCS. 1975. Soil Survey of Jefferson County. Prepared in cooperation with
Washington Agriculture Experiment Station.
Winter, D.F., K. Banse and G.C. Anderson. 1975. The dynamics of phytoplankton
blooms in Puget Sound, a fjord in the northwestern United States. Mar. Biol. 29:139-
176.
39