In cooperation with Washington State Department of Natural Resources 

Bathymetry, Substrate and Circulation 

in Westcott Bay, San Juan Islands, 

Washington 

By Eric Grossman, Andrew Stevens, Chris Curran, Collin Smith, and Andrew Schwartz 

Open-File Report 2007-1305 

U.S. Department of the Interior 

U.S. Geological Survey
U.S. Department of the Interior 

Dirk Kempthorne, Secretary 

U.S. Geological Survey 

Mark Myers, Director 

U.S. Geological Survey, Reston, Virginia 2007 

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Suggested citation: 

Grossman, EE, Stevens, A, Curran, C., Smith, C, and Schwartz, A. 2007, Bathymetry, 

substrate and circulation in Westcott Bay, San Juan Islands, Washington 

U.S. Geological Survey Open-File Report 2007-1305, pp. 42. 

Available online at: http:pubs.usgs.gov/of/2007/1305/

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Although this report is in the public domain, permission must be secured from the 

individual copyright owners to reproduce any copyrighted material contained within 

this report. 

2 
Contents 

Abstract................................................................................................................................................. 6 

Introduction .......................................................................................................................................... 7 

 Study Area ..................................................................................................................................... 7 

Data Acquisition .................................................................................................................................. 8 

 Bathymetric mapping................................................................................................................... 8 

Sediment samples for grain size analyses ..................................................................................... 9 

 Nearshore currents.................................................................................................................... 11 

Results ................................................................................................................................................. 12 

 Bathymetry and geomorphology.............................................................................................. 12 

 Sediment grain size distribution............................................................................................... 15 

 Nearshore currents and circulation ....................................................................................... 23 

Conclusion .......................................................................................................................................... 28 

Acknowledgements .......................................................................................................................... 28 

References ......................................................................................................................................... 29 

Revision Information ......................................................................................................................... 29 

Data Catalogue .................................................................................................................................. 30 

Appendix I. Bathymetry-ADCP Log ................................................................................................ 31 

Appendix II. Sediment Sampling Log. ............................................................................................ 37 

Appendix III. Sediment Grain Size Results ................................................................................... 40 

3 
Figures 

1. Location map showing Westcott Bay and study area............................................................. 7 

2. Map of survey track lines ............................................................................................................. 8 

3. Map showing sediment grab sample locations...................................................................... 10 

4. Photograph of sediment grab sample WB9............................................................................. 10 

5. Map of ADCP survey lines .......................................................................................................... 12 

6. Surface map of Westcott Bay.................................................................................................... 13 

7. Map of seafloor slope in Westcott Bay.................................................................................... 14

8. Map of mean grain size in mm ................................................................................................... 15 

9. Map of mean grain size classified by classes (in mm).......................................................... 16 

10. Map of mean grain size in phi units ......................................................................................... 17 

11. Map of mean grain size classified by classes (in phi).......................................................... 18 

12. Map of sediment sorting ............................................................................................................ 19 

13. Map of percent sand occurrence ............................................................................................ 20 

14. Map of percent silt occurrence................................................................................................ 21 

15. Map of percent clay occurrence.............................................................................................. 22 

16. Map of depth-averaged current velocity during flooding tide of May 31, 2007 ............... 23 

17. Cross-sectional diagram of ADCP derived current velocity, current direction 

 and backscatter during flooding tide of May 31, 2007. ................................................... 24 

18. Map of depth-averaged current velocity during ebbing tide of June 2, 2007 .................. 25 

19. Cross-sectional diagram of ADCP derived current velocity, current direction 

 and backscatter during ebbing tide of June 2, 2007 ....................................................... 26 

20. Map of depth-averaged currents over a 2- hour period on May 31, 2007 ........................ 27 

4 
Appendixes 

Appendix I. Bathymetry/ADCP Survey Log for USGS Cruise ID (B-6-07-PS).......................... 31 

Appendix II. Sediment Sampling Log (B-6-07-PS)....................................................................... 37 

Appendix II. Grain size results. Size classes in percent. ........................................................... 40 

5 
Bathymetry, Substrate, and Circulation in 

Westcott Bay, San Juan Islands, Washington 

Eric E. Grossman1, Andrew Stevens2, Christopher Curran3, Collin Smith5, and Andrew 

Schwartz5 

1 U.S .Geological Survey, Pacific Science Center, Santa Cruz, CA 2 U.S. Geological Survey, Menlo Park, CA 

3 U.S. Geological Survey, Washington Water Science Center, Tacoma, WA 3 U.S. Geological Survey, Western Fisheries Research Center, Cook, WA 3 Washington State Department of Ecology, Olympia, WA 

 

 

Abstract 

Nearshore bathymetry, substrate type, and circulation patterns in Westcott Bay, San 

Juan Islands, Washington, were mapped using two acoustic sonar systems, video and 

direct sampling of seafloor sediments. The goal of the project was to characterize 

nearshore habitat and conditions influencing eelgrass (Z. marina) where extensive loss 

has occurred since 1995. A principal hypothesis for the loss of eelgrass is a recent 

decrease in light availability for eelgrass growth due to increase in turbidity associated 

with either an increase in fine sedimentation or biological productivity within the bay. To 

explore sources for this fine sediment and turbidity, a dual-frequency Biosonics sonar 

operating at 200 and 430 kHz was used to map seafloor depth, morphology and 

vegetation along 69 linear kilometers of the bay. The higher frequency 430 kHz system 

also provided information on particulate concentrations in the water column. A boatmounted 600 kHz RDI Acoustic Doppler Current Profiler (ADCP) was used to map 

current velocity and direction and water column backscatter intensity along another 29 

km, with select measurements made to characterize variations in circulation with tides. 

An underwater video camera was deployed to ground-truth acoustic data. Seventy one 

sediment samples were collected to quantify sediment grain size distributions across 

Westcott Bay. Sediment samples were analyzed for grain size at the Western Coastal and 

Marine Geology Team sediment laboratory in Menlo Park, CA. These data reveal that the 

seafloor near the entrance to Westcott Bay is rocky with a complex morphology and 

covered with dense and diverse benthic vegetation. Current velocities were also measured 

to be highest at the entrance and along a deep channel extending 1 km into the bay. The 

substrate is increasingly comprised of finer sediments with distance into Westcott Bay 

where current velocities are lower. This report describes the data collected and 

preliminary findings of USGS Cruise B-6-07-PS conducted between May 31, 2007 and 

June 5, 2007. 

6 
Introduction 

In response to recent, extensive loss of the eelgrass Z. marina throughout the San 

Juan Islands (Berry et al. 2003; Wyllie-Echeverria et al. 2003), scientists from 

Washington State Department of Natural Resources (WADNR) Aquatic Resources 

Division, University of Washington (UW), and the U.S. Geological Survey (USGS) have 

initiated studies of nearshore habitat structure and hydrodynamic processes to examine 

possible stressors. A principal hypothesis for the loss of Z. marina in Westcott Bay, San 

Juan Island, is a recent decrease in light availability for eelgrass growth due to increase in 

turbidity associated with either an increase in fine sedimentation or biological 

productivity within the bay. To examine conditions influencing possible Z. marina

recovery in Westcott Bay Z. marina transplant studies were paired with time-series water 

column property measurements during the summer of 2007 as part of the WA DNR 

“Eelgrass Stressor-Response Project”. To characterize sources and processes influencing 

sediment transport and turbidity that affect light conditions for Z. marina, bathymetric, 

substrate, and circulation mapping were conducted. This report describes the bathymetry, 

substrate, and circulation data collected and preliminary findings that relate to the 

nearshore and Z. marina habitat in Westcott Bay. 

Study Area 

Westcott Bay is located along the northwest coast of San Juan Island (Figure 1). 

Figure 1. Location map showing Westcott Bay study area. 

7 
Westcott Bay is 3 km in length and averages 800 m in width and is connected to 

Garrison Bay inside of a narrow (150 m) mouth opening into Mosquito Pass. Westcott 

Bay is relatively shallow reaching a maximum depth of approximately -8.5 m, although 

35% of the bay is less than -2 m and 48% is less than -3 m. It is bounded by a relatively 

low relief watershed composed of Paleozoic and Mesozoic sedimentary rocks that have 

been folded into a broad syncline, some of which have been metamorphosed by igneous 

rocks of Mesozoic age. Two small intermittent streams discharge into the head of the bay. 

Westcott Bay is oriented WSW-ENE and because of its narrow mouth, receives little 

swell in the form of wind waves originating from summertime northwest and periodic 

wintertime southwest fetch. This region of the San Juan Islands is characterized by a 3.5-

4.0 m tide regime which generates strong observable tidal currents in Mosquito Pass. 

Sediment sources for Westcott Bay are likely to include fluvial-derived sediment input 

from the two small streams, erosion of bedrock outcrops near headlands and along the 

seafloor, autochthonous organic matter and calcareous shell production, and possibly 

import of fine materials from outside the bay through advection. 

 

Data Acquisition 

Bathymetric mapping 

Sixty-nine (69) kilometers of acoustic bathymetry/substrate data were collected with a 

dual-frequency (200 and 430 kHz) Biosonics DT-X sonar system along 142 transects in 

Westcott and Garrison Bays between 5/31/07 and 6/2/07 (Fig. 2, Appendix 1). 

Fig. 2. Map of survey track lines 

where bathymetry and acoustic 

substrate data (red) and topographic 

RTK-DGPS data (yellow) were 

collected

8 
The Biosonics sonar generates a 6-degree cone of sound, which translates into a footprint 

on the seafloor ranging 0.2 to 0.8 m for the water depths surveyed (2 - 8 m). Ship speed 

generally ranged 4.0-4.5 kts and data were merged with GPS positions at 1 Hz. Resulting 

data therefore represent 0.2-0.8 m pixels on the seafloor spaced approximately 1-2 m 

apart along track lines. Track lines were spaced 25 m apart. Twenty (20) km of 

topographic elevation data were also collected across the upper intertidal region by 

walking the shoreface with a portable Trimble 4700 RTK-DGPS receiver. This receiver 

utilized a Trimble Zepher Antenna and Pacific Crest radio receiver to obtain real time 

position corrections from a base station operating a Trimble 4400 receiver and L1/L2 

antenna with a Pacific Crest 35 Watt radio transmitter. Elevation data over emergent 

beaches and tide flats collected by walking are 2-3 times denser as a result of survey 

speeds ranging 0.5-1.0 kts. The combined bathymetric and topographic data were merged 

to create a digital elevation model representing the surface topography of Westcott Bay. 

This surface is referenced to the WGS 84 datum in the UTM Zone 10 North projection 

with a horizontal accuracy of 2.3 cm. Elevations are referenced to NAVD88 with an 

estimated vertical accuracy ranging 2.6-9.8 cm. This includes error from the RTK-DGPS 

and Biosonics sonar, and errors introduced in data processing. The root mean square 

(RMS) error of the processed surface elevation values were derived from survey line 

crossings. Line crossings did not always capture the same point on the seafloor (because 

of GPS accuracy, navigation, currents, and timing of data recording). Therefore, 

variability in elevation values at crossings is likely in part derived from variability in the 

bathymetry of the seafloor where line crossings spanned 0.5 to 2 m apart in the 

horizontal. 

Because there can be significant natural variability in depth/elevation across 0.5 to 2.0 

m of the seafloor, the vertical error of the survey was determined from analysis of three 

classes of elevation values at line crossings: 

1) values within 2 m of each other from all areas of Westcott Bay including vegetated, 

rocky and smooth areas (RMS=9.8 cm, n=66) 

2) values within 2 m of each other from the smooth area between Bell Point and the head 

of Westcott Bay (RMS=3.6 cm, n=22) 

3) values within 0.5 m of each other within the smooth area between Bell Point and the 

head of Westcott Bay (RMS=2.6 cm, n=6) 

The overall error for the entire survey is therefore 9.8 cm, although particular areas, 

especially characterized by low relief likely have much smaller errors. 

 

Sediment Samples for Grain Size Analyses 

Sediment samples were collected using a van veen grab sampler at 71 stations on a 

200-250 m grid (Fig. 3) to characterize grain size distribution throughout Westcott Bay 

and sources of fine material for suspension and transport. 

9 
Fig. 3. Map showing sediment grab sample locations.

The shallow stratigraphy was well-preserved in the sediment grabs so that a 1-3 cm 

thick aerated surface layer could be observed at most stations dominated by fines (Figure 

4). 

Fig. 4. Photo of sediment grab sample 

WB9 showing fluffy, light colored, 

aerated top layer overlying a sharp 

contact (arrow) with a denser, cohesive 

mud/clay below.

10 
In the field, a sub-sample of the uppermost 1-3 cm of each grab was collected and 

placed into storage bags, labeled, logged, and frozen. Several 10-cm push cores were also 

collected. Triplicate samples were collected at sites WBN and BP for error analyses. 

Appendix 2 summarizes sample times and environmental conditions at collection sites. 

In the laboratory, sediment samples were split for grain size and carbon analyses and 

later archived at the Western Coastal and Marine Geology Team sediment laboratory in 

Menlo Park, CA. Samples were disaggregated and sieved through 2000 and 62 micron 

screens to separate gravel, sands and mud after the organic component was removed by 

treatment with hydrogen peroxide. Sediment grain size of sands was determined using the 

settling methods and principles of Stokes Law (Guy 1969) on the USGS 3-m long settling 

tubes. The fine fraction (silts and clays) were analyzed on a Coulter 230 Laser Particle 

Analyzer. Three samples had less than 3% intermediate fraction and were analyzed on the 

Coulter. Single sample runs were made on the tubes, while results from the laser particle 

analyzer are averages of triplicates with standard deviations around the mean ranging 18 

to 24 microns due to instrument errors. Results from the tubes and laser particle analyzer 

were merged using standard USGS methods found in the USGS particle analysis program 

pcSedSize http://water.usgs.gov/software/sedsize.html). Analyses of triplicate samples 

collected at stations WBN and BP show that inter-station variability around the mean 

grain size ranged ±0.054 mm. The complete grain size results are provided in Appendix 

3. These results were then gridded across the bathymetric surface with a nearneighbor 

gridding algorithm averaging between the three nearest points. 

Video of the seafloor was collected along several principal transects in the western 

and central portions of Westcott Bay to ground-truth the sonar data and provide direct 

observations of the complex substrate, substrate transitions, and benthic vegetation. 

These results will be furnished in subsequent revisions to this report. 

Nearshore Currents 

Current velocity, direction and backscatter amplitude were collected along 65 

transects in Westcott Bay (Fig. 5) with a 600 kHz RDI ADCP (Acoustic Doppler Current 

Profiler) and recorded with WinRiver software following Oberg and others, (2005). 

Select transects at the mouth of Westcott Bay, Bell Point and immediately east of the 

Westcott Sea Farm were repeated ~2-3 times under flooding and ebbing tides. ADCP 

were recorded with GPS position at 1 hz with a ship speed of 2.0-2.5 kts, so raw ADCP 

data cover a lateral distance of 1.00 to 1.25 m. The raw ADCP data were vertically 

binned at 0.25 m and include a blanking distance of 0.25 m (no data in uppermost 0.25 m 

below the transducer). The RDI ADCP is accurate to within 0.25% of boat + water 

velocity, resulting in an error for our velocity data of 0.25 to 0.45 cm/s based on our 

survey speed of 2 kts and measured velocities ranging 0 to 1.5 m/s. 

11 
Fig. 5. Map of ADCP survey lines. Three principal lines (bold lines) at the mouth of Westcott 

Bay, Bell Point and just east of the sea farm were repeated multiple times to examine 

variability under ebb and flood tides.

Results 

Bathymetry and geomorphology 

The resulting bathymetric surface map derived from the combined DGPS and 

biosonics sonar data shows that the seafloor of Westcott Bay is complex with high relief 

between the entrance at Mosquito Pass and Bell Point, while the head of the bay is 

shallow, smooth and lacking relief (Fig. 6). A distinct narrow channel incises to -8.5 m 

along the central axis of the outer bay and is deeper along the north edge of the entrance 

to the bay. A sill 7-8 m deep separates Mosquito Pass from Westcott Bay. The 

channel/trough extends east to the area north of Bell Point, where it gradually shallows 

12 
toward the head of the bay. The margins of the trough are relatively steep, exceeding 35-

40% slope immediately southeast of White Point (Fig. 7). These complex sill and trough 

features are likely a result of complex and strong currents, the presence of rocky substrate 

at the seafloor, and the regional glacial history. The bathymetry between Bell Point and 

the head of the bay is relatively smooth and featureless likely reflecting extensive 

sedimentation of fine material. 

Fig. 6. Surface map of Westcott Bay based on bathymetry and topographic data collected 

showing narrow linear deep trough along center axis of outer Westcott Bay and shallow smooth 

surface of the head of the bay. 

13 
Fig. 7. Map showing seafloor slope of Westcott Bay with steep slopes characterizing the complex 

sill and trough region of the western half of the bay and relatively low slopes common of the 

broad gentle seafloor at the head of the bay. 

14 
Sediment grain size distribution 

Figure 8 shows the mean grain size distribution in mm of unconsolidated sediments 

across Westcott Bay. Although the substrate was generally rocky in Mosquito pass and at 

the mouth of Westcott Bay, sand occurred within what appeared to be thin veneers of 

surface sediments. This region supported diverse communities of large kelp, seaweeds 

and algae. Along the central channel extending from Mosquito Pass to Bell Point, video 

observations along with grain size analyses indicated that the bottom was characterized 

by coarse sediments including gravel and cobbles. This region is delineated on all 

subsequent grain size distribution maps with a dotted polygon. Sand also dominates 

unconsolidated materials on the seafloor at the entrance to Garrison Bay, and near the 

intermittent stream mouths at the head of the bay and at the inlet to the marsh at the 

northeast corner of the bay. Otherwise silt predominates as the mean grain size 

throughout the central region and head of the bay. 

Fig. 8. Map of mean grain size in mm across the study area. Cobble- and pebble-rich channel 

outlined in black dotted polygon; streams shown with black arrows.

15 
Figure 9 shows the mean grain size in mm classified by predominant grain size 

classes. This better shows the isolation of medium sands and coarser material near the 

entrance to Westcott and Garrison Bays, and fine silts in the central head of the bay. 

Exceptions to this include very fine to fine sand along the shoreline at the head of the bay 

likely associated with the two creeks and lagoon that meet the shore there. 

Fig. 9. Map of mean grain size classified by classes (in mm) across the study area. In order of 

increasing size (top to bottom) beginning with <0.016 mm, fs=fine silt, ms-medium silt, 

cs=coarse silt, vfs=very fine sand, fs=fine sand, ms=medium sand, 0.5-0.9 cs=coarse sand. 

Cobble- and pebble-rich channel outlined in black dotted polygon; streams shown with black 

arrows. 

16 
Figure 10 shows the mean grain size distribution in phi units, which allows for 

slightly greater dynamic range in display of the size gradients. Similar to figure 8, sands 

are restricted to the mouth and entrance to Garrison Bay, as well as, the small intermittent 

stream mouths at the head of the bay. Silt dominates the center and head of the bay. 

Fig. 10. Map of mean grain size in phi units across the study area. Cobble- and pebble-rich 

channel outlined in black dotted polygon; streams shown with black arrows.

17 
Figure 11 displays the mean grain size in phi units classified by dominant grain size 

classes. This also shows that medium and coarse sands occur near the mouth and entrance 

to Garrison Bay, and fine silts dominate in the central head of the bay, except along the 

shore at the head of the bay where fine sand is associated with the mouth of the 

intermittent streams. 

 

Fig. 11. Map of mean grain size classified by classes (in phi) across the study area. In order of 

decreasing size (top to bottom) beginning with 0.15-0.49 vcs=very coarse sand, cs=coarse sand, 

ms=medium sand, fs=fine sand, vfs=very fine sand, cs=coarse silt, ms=medium silt, 

vfs/clay=very fine silt/clay. Cobble- and pebble-rich channel outlined in black dotted polygon; 

streams shown with black arrows. 

18 
Figure 12 shows the degree of sorting of surface sediments across Westcott Bay. This 

is the calculated standard deviation around the mean grain size. Poorly sorted areas are 

reflected in the warm (red) colors, while well sorted areas are depicted in cool (blue) 

colors. Poorly sorted sediments were common immediately inside Westcott Bay across an 

inverted, u-shape area around the entrance to Garrison Bay. Sediments were generally 

poorly sorted along the eastern central bay and at the far head of the bay. Sediments were 

well-sorted along the central axis in the head of the bay and at the easternmost stream 

mouth and lagoon inlet. Sediments were generally well sorted inside the entrance to 

Garrison Bay. These variations in sorting are likely associated with strong circulation 

processes that oscillate in and out of the bay daily and sediment sources (e.g. the 

intermittent streams). Sediments were generally poorly sorted near the sea farm. 

Fig. 12. Map of sediment sorting across the study area. Poorly sorted sediment are represented 

with warm (red) colors; well-sorted sediments with cool (blue) colors. Cobble- and pebble-rich 

channel outlined in black dotted polygon; streams shown with black arrows.

19 
Figure 13 shows the fraction of sand in surface sediments across Westcott Bay in 

percent of total size classes. At the mouth of the bay and small intermittent stream, sand 

makes up >80% of seafloor sediment. In the central bay west of Bell Point, sand 

comprises generally >50% of all material, while to the east toward the head of the bay 

sand reaches a low of 5%. 

Fig. 13. Map of percent sand occurrence across the study area. Cobble- and pebble-rich channel 

outlined in black dotted polygon; streams shown with black arrows.

20 
Figure 14 shows the fraction of silt in surface sediments across Westcott Bay in 

percent of total size classes. Silt is clearly restricted to the areas within Garrison Bay and 

within the head of Westcott Bay where it reaches a maximum of 76%. East of Bell Point, 

silt generally comprises at least 50% of the sediment. 

Fig. 14. Map of percent silt occurrence across the study area. Cobble- and pebble-rich channel 

outlined in black dotted polygon; streams shown with black arrows.

21 
Figure 15 shows the fraction of clay in surface sediments across Westcott Bay in 

percent of total size classes. Clay is largely absent west of Bell Point, except for two 

isolated stations just northwest of Bell Point where it reaches ~10%. Within the head of 

the bay, clay comprises up to 21% of the sediment. 

Fig. 15. Map of percent clay occurrence across the study area. Cobble- and pebble-rich channel 

outlined in black dotted polygon; streams shown with black arrows.

In summary, sand size sediment dominates at the mouth of Westcott and Garrison 

Bays and along the shoreline at the head of the bay near the small intermittent stream and 

lagoon inlet. Along the deep trough in the center of the bay, surficial sediments are also 

characterized by sand and coarse silt with outcrops of rock and cobbles. Inside Garrison 

Bay and the head of Westcott Bay and especially east of Bell Point, sediments are 

dominated by silt with a significant (15-20%) proportion of clay.

22 
Nearshore currents and circulation 

Figures 16 and 17 illustrate the boat-mounted ADCP-derived currents at the entrance 

to Westcott Bay under a flooding tide of May 31, 2007. The highest current velocities 

occur along the north edge of the entrance along the deep trough found there. Current 

velocities at the surface reached 0.75 to 1.00 m/s. 

Fig. 16. Map of depth-averaged current velocity averaged across 5 ensembles (lateral distance) 

during flooding tide of May 31, 2007 (inset; water level from Friday Harbor tide predictions, 

http://tidesandcurrents.noaa.gov/data_menu.shtml?stn=9449880%20Friday%20Harbor,%20WA

&type=Tide+Predictions). Current velocities were stronger along northwest edge of the entrance 

to Westcott Bay, likely associated with deeper trough there. 

23 
Fig. 17. Cross-sectional diagram of ADCP derived current velocity (top), current direction 

(middle) and measured backscatter (bottom) showing stronger current velocities along 

northwest edge of the entrance to Westcott Bay (left edge of top plot) Data averaged across 

5 ensembles (across distance). 

24 
Figures 18 and 19 illustrate the strong currents flowing out of the entrance of 

Westcott Bay under an ebbing tide of June 2, 2007. Current velocities were strongest 

(0.5-0.6 m/s) in the middle of the Westcott Bay entrance and lacked the lateral 

asymmetry observed during flood tide (Fig. 16). 

Fig. 18. Map of depth-averaged current velocity averaged across 5 ensembles (lateral distance) 

during ebbing tide of June 2, 2007 (inset). Current velocities were strongest in the middle of 

the Westcott Bay entrance and lacked the lateral asymmetry observed during flood tide.

25 
Fig. 19. Cross-sectional diagram of ADCP derived current velocity (top), current direction 

(middle) and measured backscatter (bottom) during an ebbing tide. Currents were stronger in 

the middle of the entrance to Westcott Bay and more symmetric than during flood tide.

Data averaged across 5 ensembles (across distance) and are coarser than data in Figure 17 

because of higher boat speed during data collection. 

26 
Figure 20 shows the ADCP data collected on all transects of May 31, 2007 (from 

west to east) over the period of 2 hours as the tide flooded into Westcott Bay. Generally, 

higher currents were found along the central axis of Westcott Bay, and especially along 

the northwest edge of the entrance to Westcott Bay. A slight eddy was apparent west of 

Bell Point in the entrance to Garrison Bay with flow directed in a clockwise gyre. The 

northern portion of this eddy (black arrows) correlates with a region of poor sediment 

sorting (Fig. 12). 

Fig. 20. Map of depth-averaged current velocities and directions over a 2- hour flood tide 

period on May 31, 2007 (velocities scaled to arrow in legend and color coded: red=high, 

blue=low). Highest velocities were observed along the northern portion of the main channel 

into Westcott Bay, while lower velocities occured along the edges inside the entrance and 

generally within the central bay. A clockwise eddy was apparent west of Bell Point within the 

entrance to Garrison Bay. The northern margin of the eddy (black arrows) correlates with the 

area of poor sorting in Figure 12. 

27 
Conclusion 

Seafloor mapping using a dual-frequency Biosonics acoustic sonar along with a boatmounted ADCP and RTK-DGPS enabled characterization of seafloor depth, morphology 

and nearshore circulation patterns during a range of tide regimes. Contemporaneous 

sampling and subsequent analysis of surface sediment grain size distributions provide 

quantitative data for classifying the seafloor by principal morphology and substrate types. 

Westcott Bay seafloor composition and morphology is complex in its western half where 

high-relief bedrock and extensive reaches of sand, gravel and cobble are exposed along a 

linear channel northeast from the entrance of Westcott Bay toward Bell Point. This 

complex topography and substrate is associated with strong currents that reach 1.0 m/s 

and scour the bottom. Stronger currents along this deep channel indicate that the 

circulation is also partly controlled by the geomorphology. A sill 0.5-1.0 m shallower 

than the channel separates Westcott Bay from Mosquito Pass. The eastern half of 

Westcott Bay (east of Bell Point) in contrast, is broad, gently sloping and the surface 

sediments are dominated by high silt and clay fractions. Current velocities decreased 

steadily with distance into the head of the bay. In the central portion of Westcott Bay an 

eddy circulating in a clockwise rotation was observed during a flood tide. A portion of 

this eddy coincided with a region of poor sediment sorting and complex seafloor 

morphology. It remains uncertain if the flux, transport, and accumulation of sediment in 

Westcott Bay are adversely impacting Z. marina. Ongoing and future efforts will 

synthesize the data reported here with time series measurements of water quality to 

develop models of sediment transport and habitat conditions to explore environmental 

variability and possible thresholds of stress to eelgrass growth and recovery. 

Acknowledgements 

We thank Sandy Wyllie-Echeverria, Friday Harbor Laboratories, and Jim Slocomb 

for significant logistical support under short notice. Special thanks go to Mark Bullington 

of Westcott Bay Sea Farms for access and use of the sea farms for cruise operations. This 

work was funded by WA DNR Inter-Agency Agreement 07-324 and the U.S. Geological 

Survey Coastal and Marine Geology Program and the U.S. Geological Survey 

Multidisciplinary Studies of Coastal Habitats in Puget Sound (CHIPS) Project. 

28 
References 

Berry, H.D., A.T. Sewell, S. Wyllie-Echeverria, B.R. Reeves, T.F. Mumford, Jr., Skalski, 

R.C. Zimmerman, and J. Archer. 2003. Puget Sound Submerged Vegetation 

Monitoring Project: 2000-2002 Monitoring Report. Nearshore Habitat Program, 

Washington State Department of Resources. Olympia, WA. 60 p. 

Friends of the San Juans, J. Slocomb, S. Buffum-Field, S. Wyllie-Echeverria, J. Norris, I. 

Fraser, and J. Cordell. 2004. San Juan County Eelgrass Survey Mapping Project Final 

Report, Friday Harbor, WA, 40.p. 

Guy, H.P., 1969. Laboratory theory and methods for sediment analysis. In: Techniques of 

Water-Resources Investigations of the United States Geological Survey, United States 

Government Printing Office, Washington, DC, pp.iii-55. 

 

Oberg K.A., Morlock, S.E., and Caldwell, W.S., 2005, Quality-assurance plan for 

discharge measurements using acoustic doppler current profilers: U.S. Geological 

Survey Scientific Investigations Report 2005-5183, 46 p. 

[http://pubs.usgs.gov/sir/2005/5183/SIR_2005-5183.pdf]. 

Wyllie-Echeverria, S., Mumford, T., Gaydos, J. and Buffum, S. 2003. Z. marina declines 

in San Juan County, WA. Westcott Bay Taskforce Mini-Workshop 26, July 2003. 18. p. 

http://mehp.vetmed.ucdavis.edu/pdfs/eelgrassrpt.pdf 

 

 

 

Revision Information 

Please refer to http://pubs.usgs.gov/of/2007/1305/ for additions and revisions to this report. 

29 
Data Catalogue 

All data generated from this mapping of bathymetry, substrate type and nearshore 

currents are referenced to USGS Cruise ID B-6-07-PS. 

Metadata 

Metadata are available at URL: 

http://walrus.wr.usgs.gov/infobank/b/b607ps/html/b-6-07-ps.meta.html 

Digital surface elevation data 

A survey log summarizing line numbers, file names, survey information and 

environmental conditions are provided in Appendix 1. 

Digital x,y,z (depth) data for individual survey lines are provided as text files on the data 

CD under B-6-07-PS/bathymetry/line#.xyz and for the entire survey under 

B-6-07-PS/bathymetry/westcott0507.xyz. 

Digital sediment grain size data 

Station information for the sediment grain size samples is provided in Appendix 2 and the 

summary grain size results are listed in Appendix 3. 

Digital ADCP data 

The ADCP data with current velocity, direction and backscatter amplitude are transferred 

to DNR on the attached data CD in three formats: 

1) original WinRiver filename_T.OOO format, which can be opened with any text 

editor software 

(see B-6-07-PS/ADCP/WESTCOTT_DAY#/filename) 

 - (3 folders, one for each day) 

2) graphic JPG cross-sections of the RAW ADCP bottom tracked data by line 

(see B-6-07-PS/ADCP/WESTCOTT/ADCP_jpegs/) 

3) graphic JPG cross-sections and depth averaged maps of currents averaged 

across 5 ensembles (horizontal averaging) by line 

(see B-6-07-PS/ADCP/WESTCOTT/ADCP/processedData/) 

Please refer to Appendix 1 to cross reference filename with line number. 

30 
31

APPENDIX I. Bathymetry/ADCP Survey Log for USGS Cruise ID (B-6-07-PS) 

Line Biosonics_Filename Date Collected Elapsed 

Time (min) 

Total 

Length (m) 

ADCP_Filename Comm

line56_1 20070531_192732.dt4 39233.47745 10.13 1385.45 - 4-m contour alongshore 2line56_1a 20070531_193744.dt4 39233.48455 6.76 877.4 - Part 2 of line line126 20070531_194740.dt4 39233.49144 3.93 499.19 - shallow reef at start; algae 

line124 20070531_195257.dt4 39233.49512 2.93 447.99 - veg at start; kelp mid 

line122 20070531_195741.dt4 39233.49839 2.09 233.43 - reef at start line115 20070531_200441.dt4 39233.50326 1.46 123.97 - - line114 20070531_200633.dt4 39233.50456 1.29 132.1 - - 

line112 20070531_200912.dt4 39233.50639 1.53 155.95 - eelgrass at start; strong c

line110 20070531_201133.dt4 39233.50802 1.87 197.82 - end at dock 

line108 20070531_201509.dt4 39233.51056 2.5 264.65 - - 

line106 20070531_201843.dt4 39233.513 2.5 316.36 - - 

line104 20070531_202313.dt4 39233.51613 1.73 230.74 - end in eelgrass 

line102 20070531_202613.dt4 39233.51821 2.32 184.11 - steep rock at end with alg

line100 20070531_202924.dt4 39233.52042 1.56 186.36 - - line116 20070531_215040.dt4 39233.9102 2.29 137.74 WESC053107_000 eelgrass at end; strong cu

line113 20070531_215450.dt4 39233.91308 2.39 150.83 WESC053107_001 eelgrass at start 

line111 20070531_215830.dt4 39233.91564 4.62 278.88 WESC053107_002 circumvent dock near end 

line109 20070531_220607.dt4 39233.92093 4.7 285.15 WESC053107_003 - 

line107 20070531_221224.dt4 39233.92528 3.86 335.26 WESC053107_004 DNR Sonde at start; high 

channel 

line105 20070531_221812.dt4 39233.92931 3.19 303.98 WESC053107_005 eelgrass at start/end; plat

line103 20070531_222309.dt4 39233.93274 3.22 291.39 WESC053107_006 strong currents/backscatte

line101 20070531_222923.dt4 39233.93709 2.66 275.26 WESC053107_007 - 

line98 20070531_223323.dt4 39233.93985 3.43 322.16 WESC053107_008 veg/resuspension? mid ch

line96 20070531_223837.dt4 39233.94348 3 320.43 WESC053107_009 rock at start; high backsca

end 

line94 20070531_224300.dt4 39233.94652 4.06 427.19 WESC053107_010 rock at start; high backscaline145 20070531_224950.dt4 39233.95126 3.09 255.9 WESC053107_011 across Garrison Bay mouline92 20070531_225616.dt4 39233.95573 3.22 361.47 WESC053107_012 rock at end line90 20070531_230027.dt4 39233.95865 3.59 364.13 WESC053107_013 start just offshore of rock 
line88 20070531_230525.dt4 39233.96209 5.13 506.17 WESC053107_014 start mid Garrison Bay; ro

line86 20070531_231154.dt4 39233.96659 4.45 550.35 WESC053107_015 End mid Garrison Bay 

line84 20070531_232300.dt4 39233.97431 6.73 689.43 - start mid Garrison Bay; tu

line82 20070531_233149.dt4 39233.98042 7.33 802.11 WESC053107_016 turbid at start 

line80 20070531_234002.dt4 39233.98613 6.42 773.01 WESC053107_017 eelgrass at start; strong c

line78 20070531_234719.dt4 39233.99119 6.69 790.38 WESC053107_018 - 

line76 20070531_235515.dt4 39233.99669 6.79 764.38 WESC053107_019 - 

line74 20070601_000446.dt4 39234.00331 4.79 609.06 - - 

line72 20070601_001128.dt4 39234.00796 10.09 663.51 WESC053107_020 Bell Pt.; ADCP at 2kts 

line70 20070601_002231.dt4 39234.01563 6.92 748.56 WESC053107_021 - 

line35 20070601_011712.dt4 39234.05362 9.76 1102.25 - start E side of dock; throu

line30 20070601_012702.dt4 39234.06047 9.83 1095.63 - 2nd half of oysters E side 

line38 20070601_013911.dt4 39234.06889 8.23 783.01 - Oyster beds W side of do

line42 20070601_014748.dt4 39234.07487 8.85 1053.39 - 2nd section of oysters W 

line4 20070601_030128.dt4 39234.12602 2.97 184.64 - - line6 20070601_030543.dt4 39234.12898 3.79 420.21 - - line8 20070601_031111.dt4 39234.13278 4.56 591.91 - - line10 20070601_031654.dt4 39234.13675 6.16 713.08 - poor water quality NW he

line12 20070601_032411.dt4 39234.14179 0.77 54.84 - - 

line14 20070601_033317.dt4 39234.14811 5.73 775.76 - - 

line16 20070601_033954.dt4 39234.15271 5.99 787.77 - rough microtopography? m

end 

line18 20070601_034644.dt4 39234.15747 5.69 751.72 - poor WQ; floating debris/s

line20 20070601_035342.dt4 39234.1623 5.8 750.28 - - 

line22 20070601_040033.dt4 39234.16706 5.89 747.84 - start near DNR station; poline24 20070601_040724.dt4 39234.17181 7.5 805.2 - avoid rock at start; revetm

line26_1 20070601_041630.dt4 39234.17814 6.76 780.2 - revetment 

line28b 20070601_042418.dt4 39234.18354 6.3 819.6 - microtopography? 100-20

line1 20070601_175546.dt4 39234.74706 5.62 386.02 WESC060107_000 - 

line117_1 20070601_181300.dt4 39234.75921 2.23 121.99 WESC060107_001 - 

line68 20070601_181628.dt4 39234.76144 4.09 428.22 - Alongshore ~2m depth 

line28 20070601_182129.dt4 39234.76491 0.49 43.85 - alongshore 

line28a 20070601_182843.dt4 39234.76993 3.23 456.97 - alongshore 

line68a 20070601_183840.dt4 39234.77684 4.86 517.76 - - 

32
line66 20070601_184430.dt4 39234.7809 4.53 545.71 - - 

line64 20070601_185020.dt4 39234.78495 4.52 526.99 - - line62 20070601_185645.dt4 39234.78941 5.36 558.28 - - line60 20070601_190253.dt4 39234.79367 5.59 546.01 WESC060107_002 - 

line58 20070601_190926.dt4 39234.79821 5.16 538.53 WESC060107_003 - 

line56 20070601_191526.dt4 39234.80238 5.03 548.42 WESC060107_004 - 

line54 20070601_192149.dt4 39234.80681 2.36 264.09 WESC060107_005 - 

line52 20070601_194548.dt4 39234.82347 2.19 239.94 - - line50 20070601_194845.dt4 39234.82553 1.69 182.88 - - line48 20070601_195107.dt4 39234.82716 1.53 177.97 - - line46 20070601_195319.dt4 39234.8287 1.55 184.74 - - line44 20070601_195531.dt4 39234.83022 1.92 216.15 - - line42_1 20070601_195835.dt4 39234.83235 1.93 214.84 - - line40 20070601_200135.dt4 39234.83443 2.8 292.29 - - 

line38a 20070601_200607.dt4 39234.83759 2.79 333.72 - - line36 20070601_200924.dt4 39234.83986 2.55 327.44 - - line34 20070601_201255.dt4 39234.84231 2.77 362.52 - - line32 20070601_201618.dt4 39234.84465 2.79 329.52 - - line30a 20070601_202008.dt4 39234.84733 3.16 405.49 - - line29 - 39234.87569 - - WESC060107_006 - 

line7 - 39234.84306 - - WESC060107_007 - 

line117_1 - 39234.85427 - - WESC060107_008 - 

line109a 20070601_213757.dt4 39234.90135 3.62 266.08 WESC060107_009 - 

line120 20070601_214756.dt4 39234.90831 3.77 144.07 WESC060107_010 - 

line129 20070601_215431.dt4 39234.91285 8.27 1047.41 - alongshore deep section oline129a 20070601_220256.dt4 39234.9187 8.77 1101.94 - alongshore 

line129b 20070601_221150.dt4 39234.92488 6.65 814.84 - alongshore 

line127 20070601_222008.dt4 39234.93065 10.3 1111.56 - alongshore 

line127b 20070601_223034.dt4 39234.93789 8.93 938.82 - alongshore 

line117_1 - 39234.51984 - - WESC060107_011 - 

line1 - 39234.98581 - - WESC060107_012 - 

line137 20070601_235118.dt4 39234.99399 8.96 487.5 WESC060107_013 Garrison Bay 

line1a 20070602_000201.dt4 39235.00154 4.93 314.37 - sandlance/smelt? Eelgras

33
line147 20070602_000709.dt4 39235.00497 2.93 297.05 - - 

line149 20070602_001132.dt4 39235.00802 4.13 430.32 - - line151 20070602_001733.dt4 39235.01219 4.03 491.6 - - 

line153 20070602_002252.dt4 39235.01588 5.33 580.7 - - 

line155 20070602_003013.dt4 39235.02098 4.56 589.98 - - line157 20070602_003610.dt4 39235.02513 4.8 520.42 - - 

line159 20070602_004309.dt4 39235.02997 4.07 480.18 - - line161 20070602_004811.dt4 39235.03346 3.89 466.29 - - line163 20070602_005332.dt4 39235.03718 4.25 539.41 - - line165 20070602_010202.dt4 39235.04309 2.52 331.02 - - line167 20070602_010524.dt4 39235.04542 4.99 715.89 - - line169 20070602_011120.dt4 39235.04955 6.13 713.93 - - line171 20070602_011826.dt4 39235.05447 3.06 359.12 - - line173 20070602_012254.dt4 39235.05757 2 236.97 - - 

line175 20070602_012602.dt4 39235.05975 2.27 237.31 - - line177 20070602_012857.dt4 39235.06178 1.86 216.17 - - line179 20070602_013136.dt4 39235.06362 1.79 212.06 - - line181 20070602_013347.dt4 39235.06513 3.8 264.35 - - 

line171a 20070602_024828.dt4 39235.11699 2.26 258.12 - - line173a 20070602_025142.dt4 39235.11922 2.26 276.34 - - 

line175a 20070602_025445.dt4 39235.12135 3.33 348.32 - - line177a 20070602_025834.dt4 39235.124 2.69 330.08 - - line179a 20070602_030156.dt4 39235.12634 2.56 304.66 - - line1b 20070602_030433.dt4 39235.12816 1.97 235.78 - - line181a 20070602_030944.dt4 39235.13176 1.73 201.16 - - line183 20070602_031224.dt4 39235.1336 1.4 164.83 - - line184 20070602_031414.dt4 39235.13487 10.66 1491.02 - alongshore 

line57 20070602_032915.dt4 39235.1453 10.06 1417.65 - oyster farm 

line57a 20070602_033921.dt4 39235.15233 5.06 722.42 - oyster farm surface map line117_1 - 39235.59931 - - WESC060207_000 - 

line144 - 39235.60972 - - WESC060207_001 Garrison Bay at mouth line1 - 39235.61389 - - WESC060207_002 - 

line29 - 39235.62222 - - WESC060207_003 - 

34
line117_1 - 39235.63194 - - WESC060207_004 - 

line1 - 39235.6375 - - WESC060207_005 - line29 - 39235.64444 - - WESC060207_006 - line117_1 - 39235.65347 - - WESC060207_007 - 

line1 - - - - WESC060207_008 time in file 

line29 - 39235.66944 - - WESC060207_009 - line117_1 - 39235.67847 - - WESC060207_010 - 

line1 - - - - WESC060207_011 time in file 

line29 - 39235.69375 - - WESC060207_012 - line117_1 - 39235.70347 - - WESC060207_013 - 

line68_3 20070602_175434.dt4 39235.74623 13.69 2045.87 - alongshore 

line73 20070602_181503.dt4 39235.76045 7.16 554.73 WESC060207_014 across Mosquito Pass; bo

line73_2 20070602_193824.dt4 39235.81833 4.62 333.02 WESC060207_015 across Mosquito Pass (re

line193 20070602_194305.dt4 39235.82159 10.37 1435.99 - along main axis of Westcoline2 20070602_201318.dt4 39235.84257 13.86 1430.5 WESC060207_016 alongshore line117_1 - 39235.85417 - - WESC060207_017 - 

line126a 20070602_203845.dt4 39235.86024 4.22 455.88 WESC060207_020 - 

line123 20070602_204727.dt4 39235.86628 5.27 341.79 WESC060207_021 - 

line121 20070602_205353.dt4 39235.87074 2.53 207.56 WESC060207_022 boat wake 

line119_1 20070602_205741.dt4 39235.87338 2.02 139.15 WESC060207_023 - 

line118 20070602_210119.dt4 39235.87591 1.85 109.13 WESC060207_024 - 

line117_1 - - - - WESC060207_025 - 

line99 20070602_211052.dt4 39235.88257 3.49 209.19 WESC060207_026 eelgrass 

line97 20070602_211614.dt4 39235.88632 4.67 247.86 WESC060207_027 eelgrass 

line95 20070602_212315.dt4 39235.89116 4.65 262.69 WESC060207_028 eelgrass 

line93 20070602_212925.dt4 39235.89544 8 450.8 WESC060207_029 - line117_1 - - - - WESC060207_031 - 

line138 20070602_222112.dt4 39235.9314 3.49 457.26 - - line140 20070602_222543.dt4 39235.93454 2.99 408.46 - - line142 20070602_222930.dt4 39235.93716 2.5 335.21 - - 

line91 20070602_230431.dt4 39235.96148 2.46 325.6 - - 

line89 20070602_230728.dt4 39235.96353 2.66 359.33 - - line87 20070602_231106.dt4 39235.96605 2.59 348.12 - - 

35
line85 20070602_231421.dt4 39235.9683 3.75 418.67 - - 

line83 20070602_231849.dt4 39235.97141 3.43 432.02 - - line81 20070602_232255.dt4 39235.97425 3.79 471.36 - - line79 20070602_232712.dt4 39235.97723 3.46 480.54 - - 

36
APPENDIX II. Sediment Sampling Log (B-6-07-PS) 

Station Local_Time UTC Lon Lat Depth_m Comment 1 6/1/07 20:44 6/2/07 3:44 -123.1430877 48.60642247 2.286 - 

2 6/1/07 20:35 6/2/07 3:35 -123.1416559 48.60596625 2.1336 18.6 C 

3 6/1/07 20:28 6/2/07 3:28 -123.1396819 48.60476647 2.4384 22.4 C 

4 6/1/07 20:21 6/2/07 3:21 -123.1383557 48.6034425 2.4384 21 C 

5 6/1/07 20:10 6/2/07 3:10 -123.1379259 48.60230609 2.1336 - 

6 6/1/07 20:05 6/2/07 3:05 -123.1403608 48.60044935 3.3528 - 

7 6/2/07 16:50 6/2/07 23:50 -123.1412818 48.60175168 3.6576 - 

8 6/2/07 17:00 6/3/07 0:00 -123.1421506 48.60297386 3.6576 19 C 

9 6/2/07 17:05 6/3/07 0:05 -123.1427175 48.6044497 3.048 WBN-SONDE 

10 6/1/07 20:48 6/2/07 3:48 -123.1438967 48.60541356 3.048 - 

11 6/1/07 20:54 6/2/07 3:54 -123.1458085 48.60390776 3.3528 - 

12 6/2/07 16:27 6/2/07 23:27 -123.1449813 48.60267691 3.9624 - 

13 6/2/07 16:35 6/2/07 23:35 -123.1442752 48.60168593 3.9624 - 

14 6/2/07 16:45 6/2/07 23:45 -123.1434713 48.60059519 4.572 - 

15 6/1/07 19:24 6/2/07 2:24 -123.1421019 48.59864869 2.4384 - 

16 6/1/07 17:10 6/2/07 0:10 -123.1439795 48.5976315 2.1336 floc? 17 6/2/07 15:40 6/2/07 22:40 -123.1449351 48.59896955 4.2672 - 

18 6/2/07 16:05 6/2/07 23:05 -123.1462388 48.60026471 4.572 - 

19 6/2/07 16:09 6/2/07 23:09 -123.1473201 48.60179786 3.6576 - 

20 6/2/07 16:20 6/2/07 23:20 -123.148262 48.60313373 2.1336 - 

21 6/2/07 16:15 6/2/07 23:15 -123.1498974 48.60172972 1.9812 - 

22 6/2/07 15:20 6/2/07 22:20 -123.1492409 48.59979738 2.4384 - 

23 6/2/07 15:30 6/2/07 22:30 -123.1484785 48.59869397 5.0292 - 

24 6/2/07 15:35 6/2/07 22:35 -123.1476722 48.59758652 5.1816 - 

25 6/1/07 17:00 6/2/07 0:00 -123.1467698 48.59627812 2.286 - 

26 6/1/07 16:45 6/1/07 23:45 -123.1480227 48.59330183 2.1336 - 

27 6/1/07 16:55 6/1/07 23:55 -123.1490594 48.59477483 4.4196 - 

28 6/2/07 15:05 6/2/07 22:05 -123.1505265 48.59684596 5.1816 mud 29 6/2/07 15:15 6/2/07 22:15 -123.1516348 48.59839777 1.6764 - 

30 6/2/07 14:28 6/2/07 21:28 -123.1554968 48.59805066 1.0668 - 

31 6/2/07 14:35 6/2/07 21:35 -123.1541046 48.59609766 5.1816 - 

37
32 6/1/07 16:40 6/1/07 23:40 -123.1527509 48.59414851 3.9624 - 

33 6/1/07 16:35 6/1/07 23:35 -123.1517106 48.59270764 1.2192 - 

34 6/1/07 16:27 6/1/07 23:27 -123.1567103 48.5939465 1.8288 - 

35 6/1/07 16:20 6/1/07 23:20 -123.1575561 48.59512673 3.5052 - 

36 6/1/07 16:14 6/1/07 23:14 -123.1581907 48.59599792 7.0104 - 

37 6/1/07 15:30 6/1/07 22:30 -123.1589914 48.59715466 3.9624 - 

38 6/1/07 15:18 6/1/07 22:18 -123.1599242 48.59843233 1.524 - 

39 6/1/07 15:10 6/1/07 22:10 -123.1619828 48.59606753 1.2192 - 

40 6/1/07 15:00 6/1/07 22:00 -123.1610457 48.59478295 5.7912 - 

41 6/1/07 14:55 6/1/07 21:55 -123.1601357 48.5934547 8.5344 - 

42 6/1/07 14:40 6/1/07 21:40 -123.1593413 48.59231698 5.7912 - 

43 6/1/07 14:34 6/1/07 21:34 -123.1581413 48.59064567 1.8288 water temp 65 F 

44 6/1/07 14:28 6/1/07 21:28 -123.1595903 48.5902156 5.1816 - 

45 6/1/07 14:15 6/1/07 21:15 -123.1611018 48.5898281 2.1336 - 

46 6/1/07 14:05 6/1/07 21:05 -123.1588285 48.58774659 3.048 - 

47 6/1/07 13:50 6/1/07 20:50 -123.1640143 48.59094643 1.524 eelgrass dense 

48 6/1/07 13:40 6/1/07 20:40 -123.1645209 48.59171271 7.62 cobble 

49 6/1/07 13:35 6/1/07 20:35 -123.1649866 48.59240379 1.8288 fish 

50 6/1/07 13:32 6/1/07 20:32 -123.1656586 48.59335283 0.762 patchy eelgrass 

51 6/1/07 13:08 6/1/07 20:08 -123.1675292 48.591132 1.0668 eelgrass near DNR site 

52 6/1/07 13:00 6/1/07 20:00 -123.1668798 48.59026557 6.096 sandy 

53 6/1/07 12:57 6/1/07 19:57 -123.1663797 48.58958473 1.8288 - 

54 6/1/07 12:50 6/1/07 19:50 -123.1657538 48.58869312 0.9144 - 55 6/1/07 12:40 6/1/07 19:40 -123.170589 48.59020657 5.7912 rock, no sample 

56 6/1/07 12:25 6/1/07 19:25 -123.1702311 48.58971595 6.096 sand cobble 

57 6/1/07 12:15 6/1/07 19:15 -123.1698061 48.58911829 0.9144 eelgrass 

58 6/1/07 12:05 6/1/07 19:05 -123.1704144 48.5884425 0.4572 sand, cobble, eelgrass 

59 6/1/07 23:55 6/2/07 6:55 -123.171477 48.5888478 1.9812 Rocky, eelgrass (drops=3) 

60 6/1/07 11:35 6/1/07 21:35 -123.1729 48.58919782 8.5344 Mosquito Pass 61 6/2/07 13:28 6/2/07 20:28 -123.1425453 48.6053862 0.3048 WBN-1 

62 6/2/07 13:28 6/2/07 20:28 -123.1425453 48.6053862 0.3048 WBN-2 

63 6/2/07 13:28 6/2/07 20:28 -123.1425453 48.6053862 0.3048 WBN-3 

64 6/2/07 13:59 6/2/07 20:59 -123.1576585 48.5934125 0.4572 BP-1 

38
65 6/2/07 13:59 6/2/07 20:59 -123.1576585 48.5934125 0.4572 BP-2 

66 6/2/07 13:59 6/2/07 20:59 -123.1576585 48.5934125 0.4572 BP-3 

67 6/2/07 14:12 6/2/07 21:12 -123.1674891 48.5911956 1.524 WP-SONDE 

68 6/2/07 14:19 6/2/07 21:19 -123.1578369 48.5933055 2.5908 BP-SONDE 

69 6/2/07 14:47 6/2/07 21:47 -123.1421332 48.5996015 1.3716 WBS-SONDE 70 6/2/07 14:52 6/2/07 21:52 -123.141445 48.5995073 0.9144 WBS 

71 6/1/07 10:00 6/1/07 17:00 -123.145544 48.597332 2.4384 SF_Dock 

72 6/2/07 13:28 6/2/07 20:28 -123.1425453 48.6053862 0.3048 WBN-PUSH 73 6/2/07 13:59 6/2/07 20:59 -123.1576585 48.5934125 0.4572 BP-PUSH  NOTES: Depth=depth in meters at time of sampling (not corrected to a datum).  Triplicates taken at WBN and BP. 

 PUSH=Pushcore 6 inch. 

39
40

APPENDIX III. Grain size results. Size classes in percent. 

Station Boulder Cobble Gravel Sand Silt Clay Mud 

 Mean 

Phi 

 Mean 

mm Std_Dev Skewness K

1 0 0 0.46 80.41 15.96 3.17 19.13 3.552 0.085 1.482 2.246 2 0 0 0 61.11 31.68 7.21 38.89 4.174 0.055 2.011 1.306 3 0 0 0.6 61.16 28.84 9.4 38.25 4.102 0.058 2.354 0.975 4 0 0 3.11 87.59 6.85 2.44 9.29 2.588 0.166 1.673 1.847 5 0 0 0 90.17 7.16 2.67 9.83 3.015 0.124 1.473 2.733 6 0 0 0 45.37 45.31 9.32 54.63 4.731 0.038 2.112 0.866 7 0 0 0 7.02 75.28 17.7 92.98 6.207 0.014 1.816 0.651 8 0 0 0 5.82 75.34 18.84 94.18 6.34 0.012 1.799 0.607 9 0 0 0 6.08 72.56 21.37 93.92 6.486 0.011 1.888 0.264 

10 0 0 0 59.01 34.67 6.32 40.99 4.292 0.051 1.86 1.414 11 0 0 0 10.14 74.02 15.84 89.86 6.019 0.015 1.826 0.75 12 0 0 0 5.85 73.9 20.25 94.15 6.391 0.012 1.856 0.443 13 0 0 0 8.19 73.86 17.94 91.81 6.185 0.014 1.839 0.675 14 0 0 0 6.78 75.13 18.09 93.22 6.216 0.013 1.831 0.671 15 0 0 0.94 49.29 35.59 14.18 49.77 4.644 0.04 2.672 0.487 16 0 0 0.49 81.68 12.86 4.98 17.84 3.024 0.123 2.047 1.84 17 0 0 0.39 14.25 66.93 18.42 85.36 6.053 0.015 2.025 0.328 18 0 0 0 11.37 74.86 13.77 88.63 5.832 0.018 1.774 0.953 19 0 0 0 6.29 76.13 17.59 93.71 6.226 0.013 1.807 0.596 20 0 0 0 13.6 75.04 11.37 86.4 5.637 0.02 1.728 1.048 21 0 0 0 75.91 19.13 4.96 24.09 3.307 0.101 2.043 1.624 22 0 0 0 20.47 66.11 13.42 79.53 5.627 0.02 1.965 0.632 23 0 0 0.23 16.12 72.3 11.35 83.65 5.546 0.021 1.789 0.902 24 0 0 0 25.32 64.51 10.16 74.68 5.288 0.026 1.797 1.162 25 0 0 0 56.15 34.26 9.59 43.85 4.311 0.05 2.319 0.961 26 0 0 1.86 73.81 19.21 5.12 24.33 3.44 0.092 2.065 1.343 27 0 0 0 22.68 64.09 13.23 77.32 5.556 0.021 1.977 0.7 28 0 0 0 31.3 59.35 9.35 68.7 5.129 0.029 1.788 1.258 29 0 0 0.07 73.92 20.54 5.48 26.02 3.383 0.096 2.145 1.393 
30 0 0 0.07 70.95 22.17 6.81 28.99 3.504 0.088 2.273 1.3 

31 0 0 0 37.33 53.64 9.03 62.67 5.005 0.031 1.798 1.355 32 0 0 0 45.66 46.63 7.71 54.34 4.548 0.043 2.054 0.861 33 0 0 5.83 71.86 16.62 5.69 22.31 3.235 0.106 2.264 1.069 34 0 0 0 60.23 27.5 12.27 39.77 4.142 0.057 2.65 0.856 35 0 0 4.83 81.73 9.44 3.99 13.43 2.516 0.175 2.04 1.734 36 0 0 0 56.26 35.43 8.31 43.74 4.426 0.047 2.037 1.214 37 0 0 0.09 59.17 32.8 7.93 40.73 4.27 0.052 2.069 1.241 38 0 0 0 83.21 12.6 4.19 16.79 3.415 0.094 1.724 2.154 39 0 0 0 78.16 15.93 5.91 21.84 3.599 0.083 1.937 1.866 40 0 0 0 57.11 31.54 11.35 42.89 4.23 0.053 2.532 0.85 41 0 0 0 82.7 13.58 3.72 17.

3 3.393 0.095 1.63 2.318 

42 0 0 0 68.39 26.83 4.78 31.61 4.047 0.06 1.615 1.989 43 0 0 0.05 83.08 12.88 3.99 16.87 3.237 0.106 1.776 1.989 44 0 0 0 48.26 44.07 7.67 51.74 4.676 0.039 1.798 1.477 45 0 0 64.34 26.01 7.59 2.07 9.66 0.153 0.9 2.357 2.247 46 0 0 0 28.4 63.26 8.34 71.

6 5.085 0.029 1.701 1.405 

47 0 0 10 70.51 14.45 5.04 19.49 2.732 0.151 2.404 0.978 49 0 0 0 68.63 24 7.37 31.37 3.873 0.068 2.133 1.409 50 0 0 0 77.45 16.7 5.84 22.55 3.345 0.098 2.102 1.581 51 0 0 0.51 71.69 19.64 8.17 27.

8 3.601 0.082 2.334 1.315 

52 0 0 5.57 90.39 2.82 1.22 4.04 2.001 0.25 1.401 1.837 53 0 0 0 43.83 47.12 9.05 56.17 4.852 0.035 1.841 1.363 54 0 0 0 73.72 21.7 4.58 26.28 3.479 0.09 1.903 1.515 56 0 0 9.46 84.86 3.95 1.73 5.67 2.129 0.229 1.619 1.382 57 0 0 21.69 73.62 3.47 1.22 4.69 1.067 0.477 1.84 1.529 58 0 0 43.39 42.38 10.05 4.17 14.23 1.407 0.377 2.846 1.113 59 0 0 0.6 97.52 1.31 0.57 1.88 1.912 0.266 0.909 4.175 60 0 0 41.8 51.4 4.69 2.11 6.8 1.104 0.465 2.329 1.164 61 0 0 0.95 56.72 35.26 7.06 42.32 4.282 0.051 2.03 1.031 62 0 0 0 40.16 48.98 10.86 59.84 5.019 0.031 2.06 0.924 63 0 0 0 52.8 39.54 7.66 47.

2 4.489 0.045 1.977 1.167 

41
42

64 0 0 0.12 86.21 9.86 3.81 13.67 3.262 0.104 1.623 2.553 65 0 0 0 90.18 7.22 2.6 9.82 3.043 0.121 1.392 3.172 66 0 0 0.88 90.82 6.06 2.24 8.3 2.984 0.126 1.356 2.796 67 0 0 1.33 66.3 22.94 9.43 32.37 3.684 0.078 2.551 1.019 68 0 0 0 75.03 20.02 4.94 24.97 3.886 0.068 1.654 2.142 69 0 0 0 9.18 71.74 19.08 90.82 6.268 0.013 1.907 0.412 70 0 0 1.07 72.42 19.21 7.3 26.51 3.523 0.087 2.339 1.203 71 0 0 7.42 23.29 52.75 16.54 69.29 5.161 0.028 2.851 -0.363