RESULTS OF STORM SAMPLING IN THE
TILLAMOOK BAY WATERSHED
Timothy J. Sullivan
Joseph M. Bischoff
and
Kellie B Vache
May 1998
REVIEW DRAFT
E&S Environmental Chemistry, Inc.
P.O. Box 609
Corvallis, OR 97330
Results of Storm Sampling in the Tillamook Bay Watershed
E&S Environmental Chemistry, Inc. May, 1998
Page ii
TABLE OF CONTENTS
LIST OF TABLES iii
LIST OF FIGURES iv
EXECUTIVE SUMMARY vii
INTRODUCTION 1
METHODS Site Allocation and Sampling Storm Selection Routine Storm Sampling Intensive Storm Sampling Estimation of River Discharge Sample Analyses Intensive Storm Data Analyses Watershed Analyses Load Calculations 2
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RESULTS Primary Site Results Across Storms on Each River Fecal Coliform Bacteria Other Parameters Results of Load Calculations 14
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DISCUSSION Relationship Between FCB Loads and Land Use 72
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CONCLUSIONS 111
REFERENCES 112
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LIST OF TABLES
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13.
Chemical methods and detection limits for analysis of samples at Oregon State University . . 10
11
Sampling site locations for the intensive storm sampling Results of storm discharge and fecal coliform bacteria load calculations at the primary
monitoring sites on each of the five rivers that flow into Tillamook Bay during the six storms
15
that were monitored during this study First approximation estimate of annual water volume and load of TSS, TIN, TP, and FCB
71
in each of the five rivers that flow into Tillamook Bay Rank order bacteria load contributions at specific monitoring sites sampled 7 or more
times on the Tillamook River during all 12-hr time slices for which 6 or more sites were
94
sampled during the October 1997 storm Rank order bacteria load contributions at specific monitoring sites sampled 7 or more
times on the Trask River during all 12-hr time slices for which 6 or more sites were
94
sampled during the October 1997 storm Rank order bacteria load contributions at monitoring sites on the Tillamook River during
95
all 12-hr time slices sampled during the March 1998 storm Rank order bacteria load contributions at monitoring sites on the Trask River during
96
all 12-hr time slices sampled during the March 1998 storm Land use types by sample site subbasin in the Tillamook and Trask River watersheds . . . . 101
Number of farm and rural residential building clusters within each of the sample site
drainage areas included in the October 1997 and March 1998 intensively-sampled storms. 103
Land use types by sample site subbasin within a 100 m buffer zone on either side of
107
the river plus all tributary streams and drainage ditches Farm buildings and rural residental centroids occuring within 100 meter buffer of streams
109
and drainage ditches Comparison of results obtained for fecal coliform bacteria concentrations and loads
between the primary site on the Trask River (Tillamook Toll Rd. Bridge, TTR) and the
5`h St. dock, which is 0.9 miles downriver from TTR, during the two intensively-sampled
110
storms Results of Storm Sampling in the Tillamook Bay Watershed
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LIST OF FIGURES
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Wilson River hydrograph throughout the period of study. Numbers are added to the six
storms sampled in this storm monitoring effort Sample site locations for routine storm sampling Sample site locations for intensive storm sampling on the Tillamook and Trask Rivers Concentration of fecal coliform bacteria (cfu/100 ml x 10 3), 6 hour precipitation totals
(scale variable by river), and river discharge (cfs x 103) at the primary monitoring sites
on each of the five rivers for the December 1996 storm. Load of fecal coliform bacteria (cfu/sec x 10 6), 6 hour precipitation totals (scale variable
by river), and river discharge (cfs x 10 3) at the primary monitoring sites on each of the five
rivers for the December 1996 storm. Concentration of fecal coliform bacteria (cfu/100 ml x 10 3), 6 hour precipitation totals
(scale variable by river), and river discharge (cfs x 103) at the primary monitoring sites on
each of the five rivers for the January 1997 storm. Load of fecal coliform bacteria (cfu/sec x 10 6), 6 hour precipitation totals (scale variable
by river), and river discharge (cfs x 10 3) at the primary monitoring sites on each of the
five rivers for the January 1997 storm. Concentration of fecal coliform bacteria (cfu/100 ml x 10 3), 6 hour precipitation totals
(scale variable by river), and river discharge (cfs x 103) at the primary monitoring sites
on each of the five rivers for the March 1997 storm. Load of fecal coliform bacteria (cfu/sec x 10 6), 6 hour precipitation totals (scale variable
by river), and river discharge (cfs x 10 3) at the primary monitoring sites on each of the
five rivers for the March 1997 storm. Concentration of fecal coliform bacteria (cfu/100 ml x 10 3), 6 hour precipitation totals
(scale variable by river), and river discharge (cfs x 103 ) at the primary monitoring sites
on the Tillamook and Trask Rivers for the October 1997 storm. Load of fecal coliform bacteria (cfu/sec x 10 6), 6 hour precipitation totals (scale variable
by river), and river discharge (cfs x 10 3) at the primary monitoring sites on the Tillamook
and Trask Rivers for the October 1997 dorm Concentration of fecal coliform bacteria (cfu/100 ml x 10 3), 6 hour precipitation totals
(scale variable by river), and river discharge (cfs x 103) at the primary monitoring sites
on each of the five rivers for the February 1998 storm. Load of fecal coliform bacteria (cfu/sec x 10 6), 6 hour precipitation totals (scale variable
by river), and river discharge (cfs x 103) at the primary monitoring sites on each of the
five rivers for the February 1998 storm. Concentration of fecal coliform bacteria (cfu/100 ml x 10 3), 6 hour precipitation totals
(scale variable by river), and river discharge (cfs x 103) at the primary monitoring sites
on the Tillamook and Trask Rivers for the March 1998 storm. Load of fecal coliform bacteria (cfu/sec x 10 3), 6 hour precipitation totals (scale variable
by river), and river discharge (cfs x 10 3) at the primary monitoring sites on the Tillamook
and Trask Rivers for the March 1998 storm. Concentration of total suspended solids (mg/L), 6 hour precipitation totals (scale variable
by river), and river discharge (cfs x 103) at the primary monitoring sites on each of the
five rivers for the December 1996 storm. Load of total suspended solids (mg/sec x 10 3), 6 hour precipitation totals (scale variable
by river), and river discharge (cfs x 103) at the primary monitoring sites on each of the
five rivers for the December 1996 storm. Concentration of total suspended solids (mg/L), 6 hour precipitation totals (scale variable
by river), and river discharge (cfs x 103) at the primary monitoring sites on each of the
five rivers for the January 1997 storm. Load of total suspended solids (mg/sec x 10 3 ), 6 hour precipitation totals (scale variable
by river), and river discharge (cfs x 103) at the primary monitoring sites on each of the
five rivers for the January 1997 storm. 3
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Results of Storm Sampling in the Tillamook Bay Watershed E&S Environmental Chemistry, Inc.
20.
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May, 1998
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Concentration of total suspended solids (mg/L), 6 hour precipitation totals (scale variable
by river), and river discharge (cfs x 103) at the primary monitoring sites on each of the
five rivers for the March 1997 storm. Load of total suspended solids (mg/sec x 103), 6 hour precipitation totals (scale variable
by river), and river discharge (cfs x 103) at the primary monitoring sites on each of the
five rivers for the March 1997 storm. Concentration of total suspended solids (mg/L), 6 hour precipitation totals (scale variable
by river), and river discharge (cfs x 103) at the primary monitoring sites on each of the
five rivers for the February 1998 storm. Load of total suspended solids (mg/sec x 103), 6 hour precipitation totals (scale variable
by river), and river discharge (cfs x 103) at the primary monitoring sites on each of the
five rivers for the February 1998 storm. Concentration of total inorganic nitrogen (mg/L), 6 hour precipitation totals (scale variable
by river), and river discharge (cfs x 10 3) at the primary monitoring sites on each of the
five rivers for the December 1996 storm. Concentration of total inorganic nitrogen (mg/L), 6 hour precipitation totals (scale variable
by river), and river discharge (cfs x 103) at the primary monitoring sites on each of the
five rivers for the March 1997 storm. Load of total inorganic nitrogen (mg/sec), 6 hour precipitation totals (scale variable by
river), and river discharge (cfs x 10 3) at the primary monitoring sites on each of the
five rivers for the December 1996 storm. Load of total inorganic nitrogen (mg/sec), 6 hour precipitation totals (scale variable
by river), and river discharge (cfs x 103) at the primary monitoring sites on each of the
five rivers for the March 1997 storm. Concentration of total phosphorus (mg/L), 6 hour precipitation totals (scale variable
by river), and river discharge (cfs x 103) at the primary monitoring sites on each of the
five rivers for the December 1996 storm. Concentration of total phosphorus (mg/L), 6 hour precipitation totals (scale variable
by river), and river discharge (cfs x 10 3) at the primary monitoring sites on each of the
five rivers for the March 1997 storm. Load of total phosphorus (mg/sec), 6 hour precipitation totals (scale variable by river),
and river discharge (cfs x 103) at the primary monitoring sites on each of the five rivers
for the December 1996 storm. Load of total phosphorus (mg/sec), 6 hour precipitation totals (scale variable by river),
and river discharge (cfs x 103) at the primary monitoring sites on each of the five rivers
for the March 1997 storm. Load of fecal coliform bacteria (cfu/sec x 10 6) at all sites measured along the mainstem
Tillamook River during the October 1997 storm. Load of fecal coliform bacteria (cfu/sec x 10 6) at all sites measured along the mainstem
Tillamook River during the March 1998 storm. Fecal coliform bacteria concentration (top panel) and load (bottom panel) in Simmons
Creek, at its point of entry into the Tillamook River, during the October 1997 storm. Fecal coliform bacteria concentration (top panel) and load (bottom panel) in Fawcett
Creek, at its point of entry into the Tillamook River, during the October 1997 storm. Fecal coliform bacteria concentration (top panel) and load (bottom panel) in Simmons
Creek, at its point of entry into the Tillamook River, during the March 1998 storm. Fecal coliform bacteria concentration (top panel) and load (bottom panel) in Fawcett
Creek, at its point of entry into the Tillamook River, during the March 1998 storm Load of fecal coliform bacteria (cfu/sec x 10 6) at all sites measured along the Trask
River during the October 1997 storm. Load of fecal coliform bacteria (cfu/sec x 10 6) at all sites measured along the Trask
River during the March 1998 storm. Concentration of fecal coliform bacteria measured at Memaloose Inlet, in the southern
portion of Tillamook Bay, during the October 1997 storm 47
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41. Concentration of fecal coliform bacteria measured at Memaloose Inlet, in the southern
portion of Tillamook Bay, during the March 1998 storm 42. Buffer zones delineated on the basis of distance from waterways (100m on each side
of river, tributary streams, drainage ditches) in the Tillamook River watershed 43. Buffer zones delineated on the basis of distance from waterways (100m on each side
of river, tributary streams, drainage ditches) in the Trask River watershed May, 1998
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99
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EXECUTIVE SUMMARY
Since November, 1996, E&S Environmental Chemistry, Inc. (E&S), under contract to the
Tillamook Bay National Estuary Project (TBNEP), Tillamook County, Oregon, has conducted routine
water quality monitoring and intensive storm sampling in all of the five rivers that flow into Tillamook
Bay. The purpose of this report is to present the results of the storm sampling conducted by E&S
during six rain storm events between November, 1996 and March, 1998.
There were several objectives to the storm sampling efforts. This study was designed to
investigate and quantify episodic variability in the concentrations of fecal coliform bacteria (FCB),
total suspended solids (TSS), and nutrients during storm events that occur during the rainy season
in the Tillamook watershed (about October to March). An additional objective was to estimate the
storm-based loading of each of these parameters to the bay in an effort to differentiate among the
five rivers regarding their relative contributions of various pollutants to Tillamook Bay.
Prior to and during the course of the monitoring effort, it became increasingly clear that FCB
contamination was a widespread problem throughout the basin, with highest concentration in the
Tillamook River, and highest loads in the Trask and Wilson Rivers. The source of this FCB was
expected to be variable, with the primary contributions believed to include dairy operations, septic
systems, sewer treatment plants, and urban land use. The storm monitoring effort was expanded in
the fall of 1997 to include intensive sampling during two storms at about 30 sites on the Tillamook
and Trask Rivers by E&S. One fall and one winter storm were selected for this component of the
study. The principal objective of the intensive.storm monitoring was to quantify the major
contributing areas of bacterial loads along these river systems in order to allow evaluation of land
use/bacterial load interactions. An additional objective was to evaluate differences in storm-driven
pulses of bacteria at various locations in the watersheds of these two rivers.
Storms were selected by the expected duration and intensity of rainfall subsequent to a variety
of antecedent moisture conditions. Of the storms sampled, 1 was in the fall, 2 were in the winter
and 3 were in the spring. The storms were selected in an effort to represent storms of different
intensity and differing hydrological response. Four routine storms were sampled at the primary sites
close to the mouth of each river. Routine storms were sampled for FCB, TSS, nutrients, and
conductivity. Two storms were sampled more intensively for FCB.
Subbasins that drained into each sampling site were delineated and digitized into a GIS
coverage. Using this coverage, in conjunction with estimated precipitation throughout the
watershed, correction factors were calculated for each site so that river discharge data could be
corrected for contributing area and for differential rainfall amounts according to elevation of the subbasin. River flow was then calculated at each sampling site on each river, from the correction
factors and the measured discharge at the gauging station. From these corrected flow values, FCB
loads (cfu/sec) were calculated by multiplying the FCB concentration (cfu/100 ml) by the
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instantaneous flow (ml/sec). This resulted in load estimates associated with individual sub-basins
for the Tillamook and Trask River watersheds during different time periods (12 hour time slices)
during each of the intensively sampled storm events. Loads associated with each time slice were
ranked according to the amount of loading that occurred from each river segment. Scores were
then assigned to each sub-basin or river segment across all time slices based upon the number of
times that segment ranked the highest in loading, second highest in loading, and so on. This
analysis resulted in the identification of the stream segments and their associated subbasins that
most frequently contributed the largest loads of FCB to the rivers during these two storms.
Watershed factors thought to influence loading of fecal coliform bacteria to surface waters were
also quantified using coverages produced by Alsea Geospatial (Corvallis, OR) for the TBNEP from
aerial photographs of the lowland areas (<500 ft elevation). The coverages included information
about land use and hydrology, including the locations of drainage ditches. Land use or type was
then quantified from these coverages for each subbasin that drained into a particular sampling site,
including area used for pastureland or agriculture and area of riparian zone.
Centroids were produced for the development types designated as farm building clusters and
rural residential building clusters. Each represented a discrete cluster of residential homes or farm
buildings. The total number of centroids and type for each sub-basin were then quantified.
Total storm loads for FCB were calculated for each discrete storm event sampled. This was
accomplished by calculating the area under the curve for the hydrograph of each storm, in discrete
segments corresponding to the available FCB measurements. For each segment, the FCB
measurement taken at the beginning of the time segment was averaged with the FCB concentration
measured at the end of the time segment. This average was then multiplied by the cumulative
discharge during the time segment. Discharge estimates were generateclusing the trapezoidal rule
to calculate water volume between sampling points.
Annual loads were estimated two different ways for bacteria. The first approach entailed
multiplying the flow-weighted annual average of all samples collected at each primary site by the
cumulative flow during the 1997 water year. The second approach involved assignment of a
discrete load to each storm that occurred in the 1997 water year, based on the storm-based
estimates generated for the storms sampled throughout this study. Storm loads were assigned on
the basis of season, storm size, and antecedent flow conditions. Discrete storm load estimates
were then summed to produce an estimated annual load. Results of these storm-based load
calculations, as expected, were lower than the estimates based on flow-weighted average
concentration of FCB on all sampling occasions. The estimates differed by only about 50% for the
Trask River (3,189 x 10 12 cfu versus 2,031 x 10 12 cfu), but about 100% for the Tillamook River (1,623
x 10 12 cfu versus 793 x 10 12 cfu). Annual loads for TSS, total inorganic nitrogen (TIN) and total
phosphorus (TP) were generated in a manner analogous to the first approach used for bacteria. All
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of these load estimates should be viewed as first approximations. More rigorous quantification of
storm-based, and especially annual, loads would require additional monitoring data and the
application of one or more non-point source pollution models.
The largest FCB loads were contributed during the early fall storm in 1997. Measured loads
during this storm in the Tillamook and Trask Rivers were more than twice as high as for any other
sampled storm. The smallest loads were contributed by the smallest storm (4.3 in precipitation),
which occurred in the spring of 1998.
The overall trend for both the Tillamook and Trask Rivers during both the fall and spring
intensively-sampled storms was as follows. FCB loads were low at all sites at the beginning and
generally at the end (depending on when sampling was discontinued) of the storms. At the
uppermost sites, located in the upper section of the agricultural portions of these watersheds, FCB
loads remained low. At the uppermost Trask River site (Loren's Landing), this was mainly because
FCB concentrations remained low. At the uppermost Tillamook River site (Yellow Fir Rd.), this was
because the discharge is low compared to the lower reaches of the Tillamook River (FCB
concentrations were frequently high). High loads were found at a variety of locations on both rivers.
There was not one major source area of FCB load on either river; the source areas were many and
widely scattered. The largest loads in both rivers were generally achieved in the lower two miles or
so of river reach. This suggests the cumulative effect of a large number of source areas within the
agricultural portions of the watersheds and/or a larger contribution of FCB close to the bay.
A site in the bay was monitored during the two intensive storm monitoring efforts. It was
adjacent to Memaloose Boat Launch, just north of where the Tillamook and Trask Rivers enter
Tillamook Bay. During the October, 1997 storm, FCB concentrations exceeded 1,000 cfu/100 ml on
over half of the sampling occasions, with a peak concentration of nearly 3,000 cfu/100 ml. These
are extremely high concentrations given that the bacterial standard for protecting the oyster beds
located just north of this sampling location is only 14 cfu/100 ml. Even during the spring storm,
which resulted in much lower FCB loads in the Tillamook and Trask Rivers, the FCB concentration
at Memaloose Inlet was about 500 to 1,000 cfu/100 ml on half of the sampling occasions.
Evaluation of the spatial land use patterns within the contributing drainage areas to each of the
monitoring sites revealed some interesting patterns. Highest loads were associated with high
percent urban land use, high percent rural residential land use, and finally high percent agricultural
land use. Large numbers of rural residential building clusters were also frequently associated with
high FCB loads. These findings provide very strong, albeit circumstantial, evidence that the largest
FCB loads within these two watersheds may in fact be provided by human activities other than dairy
farming. Urban areas appear to be significant contributors, as do rural residential areas. The latter,
however, may also contain intensive dairy farming activities in some cases.
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These same land use analyses were repeated for a set of drainage areas (subbasins) defined
in a different way. For this second set of land use analyses, the drainage areas contributing to each
sampling site were restricted to those within 100m on either side of waterways (river, tributary
streams and/or drainage ditches). The results of these analyses further supported the findings that
high FCB loading was generally associated with urban and rural residential land use, and to a lesser
extent agricultural land use.
These results suggest that the largest contributions of FCB to the Tillamook and Trask Rivers,
at least during the two storms that were intensively monitored, occurred in associated with human
habitation, especially the urban and rural residential areas of the Trask River watershed and the
rural residential and agricultural areas of the Tillamook River watershed. Highest loads were often
found in the lower sections of the rivers, which are heavily ditched and where human activity is
concentrated, soils are poorly drained, and runoff potential is high.
Key conclusions of this research include the following:
• The largest loads of FCB to Tillamook Bay are contributed by the Trask River, followed by
the Wilson and then the Tillamook River. FCB loads in the Miami and Kilchis Rivers are
lower than the other three rivers by about an order of magnitude.
• The largest loads of nitrogen to Tillamook Bay are contributed by the Trask River, followed
by the Wilson River.
• The largest loads of TSS and TP (which are likely both primarily from erosional materials)
are contributed by the Wilson River, followed by the Trask River.
• FCB loads in a given river differed markedly from storm to storm, with highest loads (by a
substantial margin) contributed by the early fall storm.
• The highest concentrations of FCB were generally achieved well before the time of peak
river discharge, and generally occurred during the period of most ihtensive rainfall.
• The largest FCB storm loads were reached in the mid-section of the Tillamook River and the
lower sections of both the Tillamook and Trask Rivers. However, FCB contributions were
substantial throughout both watersheds.
• The land areas that contributed the largest FCB loads to the Trask River were those
containing urban land use. Other land uses associated with areas that contributed large
FCB loads were rural residential and agricultural land use. The land uses that contributed
the largest FCB loads to the Tillamook River (whose watershed does not include urban land
use) were rural residential and agricultural land uses.
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INTRODUCTION
Tillamook Bay and its watershed have been the site of intensive water quality monitoring since
November, 1996. E&S Environmental Chemistry, Inc. (E&S), under contract to the Tillamook Bay
National Estuary Project (TBNEP), Tillamook County, Oregon, has conducted routine water quality
monitoring in all of the five rivers that flow into Tillamook Bay. In addition, intensive storm sampling
has been conducted by E&S at a variety of sites during six rain storm events between November,
1996 and March, 1998. Additional sampling was also conducted on behalf of TBNEP by other
agencies and cooperating institutions during two of those storms. Results of the work conducted by
E&S is being reported in several technical reports to TBNEP. Quality assurance/quality control
issues were addressed by Bernert and Sullivan (1997). Results of the routine monitoring efforts
were presented by Sullivan et al. (in review). The purpose of this report is to present the results of
the storm sampling conducted by E&S. Results of storm sampling conducted by other participating
agencies and organizations will be summarized elsewhere.
There were several objectives to the storm sampling efforts. It is well known that several
important water quality parameters typically exhibit significant episodic variability. Chief among
these in the Tillamook Basin are fecal coliform bacteria (FCB) and total suspended solids (TSS).
There was also concern about the possibility of episodic pulses of nutrients in river water in the
basin. This study was designed to investigate and quantify episodic variability in the concentrations
of FCB, TSS and nutrients during storm events that occur during the rainy season in the Tillamook
watershed (about October to March). An additional objective was to estimate the storm-based
loading of each of these parameters to the bay in an effort to differentiate among the five rivers
regarding their relative contributions of various pollutants to Tillamook Bay.
Prior to and during the course of the monitoring effort, it became increasingly clear that FCB
contamination was a widespread problem throughout the basin, with highest concentration in the
Tillamook River, and highest loads in the Trask and Wilson Rivers (c.f., Jackson and Glendening
1982, Sullivan et al. in review). The source of this FCB was expected to be variable, with the
primary contributors believed to include dairy operations, septic systems, sewer treatment plants,
and urban land use (c.f., Jackson and Glendening 1982). The storm monitoring effort was
expanded in the fall of 1997 to include intensive sampling during two storms at about 30 sites on the
Tillamook and Trask Rivers by E&S, and at eight sites on the Wilson River by the Tillamook County
Creamery Association (TCCA). One fall and one winter storm were selected for this component of
the study. The principal objective of the intensive storm monitoring was to quantify the major
contributing areas of bacterial loads along each of these river systems to allow evaluation of land
use/bacterial load interactions. An additional objective was to evaluate differences in storm-driven
pulses of bacteria at various locations in the watersheds of these three rivers.
Results of Storm Sampling in the Tillamook Bay Watershed
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Page 2
METHODS
Site Allocation and Sampling
Storm Selection
Storm monitoring was initiated in November, 1996 and six storms were sampled through April
1998. Storms were selected by the expected duration and intensity of rainfall subsequent to a
variety of antecedent moisture conditions. Of the storms sampled, one was in the fall, two were in
the winter and three were in the spring. The storms were selected in an effort to represent storms
of different intensity and differing hydrological response. The early fall storm was preceded by a
long dry period when there was little flushing of the watersheds. Winter storms were preceded by
wetter antecedent conditions and more continual flushing of the watersheds due to frequent large
rainfall events. Spring storms represented intermittent dry and wet periods. Storms were chosen so
that each of these storm types and associated antecedent moisture conditions were represented to
the extent possible.
Two categories of sampling were included: routine and intensive. Four routine storms were
sampled at the primary sites close to the mouth of each river and at a few selected secondary sites.
Routine storms were sampled for fecal coliform bacteria (FCB), total suspended solids (TSS),
nutrients, and conductivity. During the course of the study, it became apparent that the
environmental variable of greatest interest with respect to storm response was FCB. An approach
was therefore designed to sample two storms more intensively for FCB. These intensive storm
sampling activities were confined (by E&S) tolhe Tillamook and Trask Rivers, which generally
experience the highest FCB concentrations and loads, respectively. The same storms were also
sampled on the Wilson River by the Tillamook County Creamery Association (TCCA) and on the
Miami and Kilchis Rivers by the Oregon Department of Environmental Quality (ODEQ). In addition,
some sampling of the bay was carried out by ODEQ, E&S, and by the Oregon Department of
Agriculture (ODA).
The Wilson River hydrograph throughout the period of study is depicted in Figure 1. It shows
the pattern typical of the Tillamook Basin: low river flows (generally <500 cfs) during summer and
frequent storms from October through March. The largest storms generally occur in the period
November through January and often achieve peak discharge >10,000 cfs on the Wilson River.
Flood stage on the Wilson River is designated as 14,100 cfs. The storms that were monitored
during this study are indicated in Figure 1.
Routine Storm Sampling
Primary sites (one on each river) and a few additional secondary sites were sampled for four of
the storm events (Figure 2). In consultation with TBNEP staff, a primary site was selected at the
downstream end of each of the five rivers (Miami, Kilchis, Trask, Wilson, Tillamook), in relatively
May, 1998
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close proximity to the bay. A few secondary sites were also sampled during these storms.
Selection of secondary sites was based on criteria such as known or suspected problem locations,
forest/agriculture interface locations, and sampling logistics. All sample sites were selected with an
aim to avoid tidal prism influence. To quantify tidal influence, on-site conductivity measurements
were taken to determine if baywater contamination of samples occurred. Road crossings (bridges)
were selected for primary site sampling locations for logistical purposes. Bridge sampling,
accomplished using a Van Dorn sampler or a weighted sterile bottle, facilitated collection of water in
the middle of the current (at a depth of about 0.5 m) where water tends to be well mixed. Shallow
sites or sites without bridge crossings were sampled from shore by submerging a Nalgene bottle
directly in the stream using a pole to sample at depth and avoid sample contamination. Samples
were filled to minimize air bubbles and the bottles placed in coolers on ice and transported to the
Oregon State University Soil Science Laboratory in Corvallis for chemical analyses and the Kilchis
Analytical Laboratory in Bay City for bacterial analyses.
During the course of the study, the Burton Bridge (primary site location on the Trask River)
became the site of extensive construction activity. Beginning in late 1997, this site was no longer
available for sample collection because the bridge had been largely removed. The 5th Street dock,
0.9 miles downstream from Burton Bridge, was sampled as the new primary site on the Trask River
during Storm 3.
Intensive Storm Sampling
Two storms (October 1997 and March 1998) were sampled intensively at about 30 sites on the
Tillamook and Trask Rivers (Figure 3). The Wilson River was sampled by the TCCA during the
same storm events and those results will be presented in a subsequent report. Samples were
collected along each of the two rivers from the mouth to near the forest/agriculture interface. Site
selection was determined jointly by members of the project team and TBNEP staff. Most, but not all,
sites were sampled on each sampling occasion. Priorities for site location and sampling were
forest/agriculture transitions, downriver of confluence of tributary streams, probable point sources of
bacteria and nutrients, and areas of intensive agriculture.
Many sites included in the intensive storms were sampled from a boat using a weighted sterile
bottle. Some sample locations were not accessible from the boat (too shallow or boats not
permitted) and consequently these sites were either sampled from bridges or from shore as
described in the routine storm sampling section. The spatially intensive sampling program allowed
identification of stream reaches and specific watershed regions that play significant roles in fecal
coliform bacteria contribution to the rivers.
The Tillamook, Trask and Wilson Rivers were selected for the intensive sampling program
because they were identified as the rivers that play the largest roles in fecal coliform contribution to
Results of Storm Sampling in the Tillamook Bay Watershed
E&S Environmental Chemistry, Inc.
May, 1998
Page 6
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Results of Storm Sampling in the Tillamook Bay Watershed
E&S Environmental Chemistry, Inc.
Results of Storm Sampling in the Tillamook Bay Watershed E&S Environmental Chemistry, Inc.
May, 1998
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Results of Storm Sampling in the Tillamook Bay Watershed E&S Environmental Chemistry, Inc.
May, 1998
Page 9
the bay as a result of high concentrations and high loads. Analyses reported here focus primarily on
the Tillamook and Trask Rivers.
The Tillamook River Subbasin drains 43,000 ac of mostly timber and agricultural lands, with
some residential land use. The mainstem of the river originates on the east side of the Cape
Lookout Headland about 18 miles south of the bay. There is a network of tributaries that flow into
the river from the east side of the subbasin. The lower portion of the subbasin is heavily dissected
with drainage ditches and small streams, and about 5 miles of the lower river is diked to control
flooding. The upper mainstem and west side tributary watersheds have high runoff potential, and
the portion of the watershed behind dikes and tide gates generally has very high runoff potential
(USDA-SCS 1978).
The lower 1 to 2 miles of the Trask River Subbasin, in an area of poorly drained soils, is
considered to have a very high runoff potential (Jackson and Glendening 1982). There are many
drainage ditches because of the poorly drained soils. Portions of the Trask Subbasin also contain
concentrated urban land use. The city of Tillamook is situated on a terrace between the Trask River
to the south and the sloughs to the north. Two sewage treatment plants (STPs) are located in this
subbasin. The Port of Tillamook sewage treatment facilities discharge treated effluent at RM 5. The
city of Tillamook's STP discharges at RM 1.5.
Estimation of River Discharge
River flow data for the Tillamook, Kilchis, and Miami Rivers were collected by the Oregon
Water Resources Department (OWRD) and were retrieved from field loggers monthly. Data
collection began in the summer of 1995. The USGS maintains gauging stations on the Trask and
Wilson Rivers. These data have also been gathered and included in the hydrologic data set.
E&S was provided the OWRD data files, along with a series of rating curves developed for
each of the three stations. These raw data files were merged, and estimates of discharge were
calculated from the rating curves and added to the data set.
The data set provided by OWRD for the Tillamook, Kilchis and Miami Rivers contained a
number of gaps during which stage data were not collected. These gaps were filled using a series
of simple linear regressions. Each equation corresponded to a season and was based on the
Wilson River data collected by USGS (Sullivan et al. in review).
Sample Analyses
River water samples were analyzed for total phosphorus (TP), total Kjeldahl nitrogen (TKN),
nitrate, ammonium, conductivity, total suspended solids (TSS), fecal coliform bacteria (FCB), pH
and temperature. FCB were analyzed on all sample occasions. Conductivity, temperature and TSS
were analyzed for most samples. Nitrate, ammonium, TKN, and TP were measured for a small
Results of Storm Sampling in the Tillamook Bay Watershed
E&S Environmental Chemistry, Inc. L
May, 1998
Page 10
subset of samples. The chemical analytical methods are summarized in Table 1. FCB were
analyzed using the membrane filtration method described in Standard Methods for the Examination
of Water and Wastewater (Greenberg et al. 1992). Duplicate, triplicate, and deionized water blank
samples were submitted as routine samples to the laboratory as checks on analytical quality. In situ
measurements were collected for temperature and conductivity. Sampling and analytical methods
and QA/QC were described by Sullivan et al. (in review) and Bernert and Sullivan (1997).
Intensive Storm Data Analyses
Transect analyses were performed on the Tillamook and Trask Rivers for the two intensive
storms (October 1997 and March 1998). A total of 14 sites were sampled on the Tillamook River,
plus two tributary streams, and 18 sites were sampled at various times on the Trask River. In
addition, a site in the bay was sampled at Memaloose boat ramp just to the north of where the
Tillamook and Trask Rivers enter the bay. Site locations are listed in Table 2.
Table 1.
Chemical methods and detection limits for analysis of samples at Oregon
State University.
Parameter
Detection
Method
pH, lab
Conductivity, lab
Electrode
Platinum electrode
1.0
s .u.
S/cm
Calcium, as Ca2+
AA flame
0.05
mg/L
Magnesium, as Mg2+
Sodium, as Na+
Potassium, as K+
AA flame
Flame emission
Flame emission
0.05
1.0
0.5
mg/L
mg/L
mg/L
Sulfate, as SO42-
Ion chromatography
1
mg/L
Chloride, as Cl
Nitrogen, NO 2 + NO3 as N
Ion chromatography
Ion chromatography
0.2
0.05
mg/L
mg/L
Nitrogen, NH 3 as N
Perstorp (SM4500)
0.01
mg/L
Nitrogen, Kjeldahl as N
BD-40 auto. phenate
0.05
mg/L
Phosphorus, tot. as P
Digest./ascorbic acid
0.002
mg/L
Solids, tot. susp. (TSS)
Gravimetric 103C
2
mq/L
Reporting
Limit
Unit
Results of Storm Sampling in the Tillamook Bay Watershed
E&S Environmental Chemistry, Inc. May, 1998
Page 11
Table 2. Sampling site locations for the intensive storm sampling.
River
Mile
Location Description
10.0
8.1
6.8
5.5
4.9
4.5
4
3.5
3.1
2.9
2.6
2
1.5
1.1
0.9
Yellow Fir Road
Rest Area
Bewley Bridge
Bridge by Weber Road
Tillamook River Road
Between TTR and BUR
Burton Bridge
Between BUR and ATW
Above Large Tidegate
Below Large Tidegate
Above Wetland
Fraser Road
Below Tide Gate
South Fork Trask
Netarts Highway Bridge
Tributaries to Tillamook River
TIL-FAW
TIL-SIM
8.8
8.3
Fawcett Creek Bridge
Simmons Creek Bridge
Trask River
TRA-LOR
TRA-CHA
TRA-10L
TRA-101
TRA-BTR
TRA-ATR
TRA-DST
TRA-BPS
TRA-TTR
TRA-TEF
TRA-ASF
TRA-5TH
TRA-HOB
TRA-HOQ
TRA-RMO
9
7
4.3
4.2
3.7
3.6
3.2
2.7
2.4
2.3
1.7
1.5
1.2
0.8
0
Loren's Landing
Chance Road
101 Landing
Bridge on Highway 101
Below Trailer Park
Above Trailer Park
Downstream Stream
By Piling and Stream
Tillamook River Road
Below Effluent Inflow
Above South Fork
5th St. Boat Ramp (Above STP)
Hospital Bridge
Above Hoquarten Slough Confluence
Near Confluence with Hog. Slough (RM 0)
Site Code
Tillamook River
TIL-YEL
TIL-RES
TIL-BEW
TIL-WEB
TIL-TTR
TIL-MID
TIL-BUR
TIL-MIB
TIL-ATG
TIL-BTG
TIL-AVVT
TIL-FRA
TIL-TDI
TIL-SFT
TIL-NET
Bay
MEM-INL
-0.5
Slough
HOQ-CON
0
Memaloose
Near Confluence with Trask River
Results of Storm Sampling in the Tillamook Bay Watershed
E&S Environmental Chemistry, Inc.
May, 1998
Page 12
Subbasins that drained into each sampling site were delineated and digitized into a GIS coverage.
Using this coverage, in conjunction with estimated precipitation throughout the watershed, correction
factors were calculated for each site so that flow data could be corrected for contributing area and
for differential rainfall amounts according to elevation of the sub-basin. River flow was then
calculated at each sampling site on each river, from the correction factors and the measured flow at
the gauging station. From these corrected flow values, FCB loads (cfu/sec) were calculated by
multiplying the FCB concentration (cfu/100 ml) by the instantaneous flow (ml/sec). Data were
collected over about a four to six day period during each of the storms. The days were divided into
morning and afternoon segments creating 12-hour time slices. If two or more samplings occurred
within one time slice, then the mean FCB load during the time slice was used for this analysis. This
resulted in load estimates associated with individual sub-basins for the Tillamook and Trask Rivers
watersheds during different time periods (12 hour time slices) during each of the storm events.
Consequently, load analyses could be performed during several parts of the hydrograph (rising limb,
peak, falling limb) allowing us to describe differences in fecal coliform loading both spatially (subbasins) and temporally (time slices). Loads for each sub-basin were then divided by the length of
the river segment in river miles or contributing watershed area to adjust for the different length of
stream or watershed area that was fed by the individual sub-basins. Loads associated with each
time slice were ranked according to the amount of loading that occurred from each river segment.
Scores were then assigned to each sub-basin or river segment across all time slices based upon the
number of times that segment ranked the highest in loading, second highest in loading, and so on.
The site which ranked the highest within a time slice received a score of five; the site contributing
the second largest load within a time slice was given a score of 4; and so on. The total score is the
sum across all time slices for that particular storm. This analysis resulted in the identification of the
stream segments and their associated subbasins that contributed the largest loads of FCB to the
rivers during these two storms.
Watershed Analyses
Watershed factors thought to influence loading of fecal coliform bacteria to surface waters were
also quantified using coverages produced by Alsea Geospatial (Corvallis, OR) for the TBNEP.
Coverages were produced from aerial photographs of the lowland areas (<500 ft elevation) of the
Tillamook Bay watershed and areas with some human built structures such as houses or barns.
The coverages included information about land use and hydrology, including the locations of
drainage ditches. To maintain the continuity of the layer, some higher elevation areas (ridges) were
included. Additionally, some areas less than 500 feet elevation, but with no built structures were
excluded. The Arclnfo coverages were compiled by Alsea Geospatial by edgematching National
Wetlands Inventory Arclnfo coverages and then adding linear features by screen digitizing. Linear
Results of Storm Sampling in the Tillamook Bay Watershed E&S Environmental Chemistry, Inc.
May, 1998
Page 13
•
features were screen digitized using TBNEP_ORTHO3 grid as a background layer. The grid was
compiled by scanning, orthorectifying and mosaicing 1:40,000 scale aerial photographs provided by
the Farm Service Agency. The photo year was 1994. The layer covers a portion of the Tillamook
Bay Valley less than 500 feet in elevation and containing human settlements. After features had
been screen digitized, they were attributed using codes.
Coverages were projected in UTM zone 10 for this analysis. Subbasins draining into each
sample point were delineated and digitized. Land use or type was then quantified from these
coverages for each subbasin that drained into a particular sampling site, including area used for
pastureland or agriculture and area of riparian zone. Development types were also quantified which
included the area of rural residential and urban land use within each of the subbasins. Some of
these classifications overlapped, such as rural residential and agriculture and were therefore
quantified as both types. For example, if a polygon was coded as both rural residential and
agricultural, then the area of the polygon was used in calculating both the total agricultural area and
the total rural residential area.
Centroids were produced for the development types designated as farm building clusters and
rural residential clusters. Each represented a discrete cluster of residential homes or farm buildings.
The total number of centroids and type for each sub-basin were then quantified.
Load Calculations
Total storm loads for FCB were calculated for each discrete storm event sampled. This was
accomplished by calculating the area under the curve for the hydrograph of each storm, in discrete
segments corresponding to the available FCB measurements. For each segment, the FCB
measurement taken at the beginning of the time segment was averaged with the FCB concentration
measured at the end of the time segment. This average was then multiplied by the cumulative
discharge during the time segment. Discharge estimates were generated using the trapezoidal rule
to calculate water volume between sampling points. Volumes were calculated hourly, based on
discharge data. All time segments during the storm were summed to generate the estimate of total
storm load. At the beginning and end of each storm, professional judgement was used when
necessary with available baseflow measurements of FCB concentration at each site (Sullivan et al.
in review)
to estimate the FCB concentration before the first sample was collected or after the last
sample was collected.
Annual loads were estimated two different ways for bacteria. The first approach entailed
multiplying the flow-weighted annual average of all samples collected at each primary site (Sullivan
et al. in review) by the cumulative flow during the 1997 water year. The second approach involved
assignment of a discrete load to each storm that occurred in the 1997 water year, based on the
storm-based estimates generated for the storms sampled throughout this study. Storm loads were
Results of Storm Sampling in the Tillamook Bay Watershed E&S Environmental Chemistry, Inc.
May, 1998
Page 14
assigned on the basis of season, storm size, and antecedent flow conditions. Discrete storm load
estimates were then summed to produce an estimated annual load. Annual loads for TSS, TIN and
TP were generated in a manner analogous to the first approach used for bacteria.
All of these load estimates should be viewed as first approximations. More rigorous
quantification of storm-based, and especially annual, loads would require additional monitoring data
and the application of one or more non-point source pollution models.
RESULTS
Primary Site Results Across Storms on Each River
Fecal Coliform Bacteria
Results of the analyses for fecal coliform bacteria (FCB) at the primary site on each river are
presented in Figures 4 through 15. Results for each storm are presented in two figures, one for
bacterial concentration (cfu/100 ml) and the following figure for bacterial load (cfu/sec). To facilitate
visual comparison of data across storms and across sites, the scales used in this series of figures
were standardized as much as possible. All bacterial data were presented at a uniform scale for
each bacterial representation (concentration and load). Because of large differences in discharge
among the five rivers, however, the discharge data could not be presented at a common scale. The
reader is cautioned, therefore, to carefully note the discharge scale and units for each figure, as they
are variable from storm to storm and from river to river. Also note that the precipitation data are
presented in each figure on the same scale as the discharge data, and therefore vary in scale
among sites and among storms. Each precipitation bar in this series of figures depicts the total
precipitation received during a 6-hr period.
The storm that was sampled in December, 1996 (Storm 1) was preceded by a long series of
storms on about a three day interval. Cumulative precipitation at Tillamook during the storm was
5.2 in (13cm). Peak discharge reached about 10,000 cfs on the Wilson River during this storm and
between about 4,000 and 6,000 cfs on four separate occasions during the two week period
preceding the storm (Figure 3). This was one of the largest storms sampled in the study in terms of
peak river discharge achieved (Table 3). Peak FCB concentrations were reached around the 12-hr
period of peak precipitation. Peak discharge occurred about 6 to 12 hours later. Concentrations of
FCB peaked at about 400 to 600 cfu/100 ml in all rivers except the Kilchis, which had peak
concentrations about half or less than those of the other rivers (Figure 4). FCB loads during this
storm were relatively high, especially in the Wilson and Trask Rivers, which reached peak loads of
about 1 x 106 cfu/sec (Figure 5). These high loads were largely attributable to the high discharge
during this storm, rather than unusually high FCB concentrations. Loads in the Miami and Kilchis
Rivers were much lower, with peak values around 0.2 x 106 cfu/sec. Peak FCB loads in the
Tillamook River were intermediate.
Results of Storm Sampling in the Tillamook Bay Watershed
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Results of Storm Sampling in the Tillamook Bay Watershed E&S Environmental Chemistry, Inc.
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Figure 4. Concentration of fecal coliform bacteria (cfu/100 ml x 10 3), 6 hour precipitation totals
(scale variable by river), and river discharge (cfs x 10 3) at the primary monitoring sites on
each of the five rivers for the December 1996 storm.
t
Results of Storm Sampling in the Tillamook Bay Watershed
E&S Environmental Chemistry, Inc.
May, 1998
Page 17
Wilson River
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7DEC96
Results of Storm Sampling in the Tillamook Bay Watershed
E&S Environmental Chemistry, Inc.
May, 1998
Page 18
Tillamook River
1.50 ca
"r.
1.25 7_
ID,
• — 1.00 -
co
E
8 49
=
i
•
0.75 -
t3 0.50 -
ca
c.)
a)
0.25 0.00
23NOV96
Trask River
15.0
1.25 -
12.0
a)
co
1.00 7
•
O
c
6.0
0.50
3.
o p.
0 "6
3.0 LL. 0
0.25 7
13:
c)
0.00
)
9.0 X
E x 0.75 7
:a= co
Fl
-
23NOV96
0.0
30NOV96
7DEC96
Figure 5. Load of fecal coliform bacteria (cfu/sec x 106), 6 hour precipitation totals (scale variable
by river), and river discharge (cfs x 10 3) at the primary monitoring sites on each of the
five rivers for the December 1996 storm.
1
Results of Storm Sampling in the Tillamook Bay Watershed
E&S Environmental Chemistry, Inc.
May, 1998
Page 19
Wilson River
1.50 -
ca
C)
15.0
1.25 -
- 12.0
as
co
1.00 7:
E x
0
tt.
O
C.)
-
9.0
0.75
0.50 -
is
0.25 -
C)
LL
0.0
7DEC96
Kilchis River
1.25 7
▪
•a)
•loa
1.00H
m
EE x
o
0.75 7
0
cn
=
0.50
0.25
o
a)
u_
0.00 23NOV96
Miami River
1.50
CU
1.25
s_
12
1.00
E
o
0.75
0.50
o
1.5
0.25
as
LL
0.00
Figure 5. Continued.
- 2.0
Results of Storm Sampling in the Tillamook Bay Watershed
E&S Environmental Chemistry, Inc.
May, 1998
Page 20
The storm that was sampled in January, 1997 (Storm 2) was quite different hydrologically from
the December storm. Like the December storm, the January storm was of about two days duration
and resulted in 5.5 in (14cm) of precipitation at Tillamook, but it was preceded by a relatively dry
period (Figure 6). Virtually no rain occurred during the five days before the storm, and river flows
were therefore fairly low. For example, the Wilson River discharge was less than 1000 cfs at
initiation of the January storm (Figure 6), about three-fold lower than it had been at initiation of the
December storm (Figure 5). Peak discharge in the Wilson River during the storm was about 4,500
cfs. Peak FCB concentrations generally reached higher values during Storm 2, as compared with
Storm 1, even though peak river flows were about half of the flows during Storm 1. Peak FCB
concentrations approached 1000 cfu/100 ml in the Tillamook River and exceeded that amount in the
Wilson and Trask Rivers. Concentrations in the Kilchis River remained very low (Figure 6). FCB
loads during this storm were generally lower, however, than were found during the December storm
(except for one high value, 1.5 x 10 6 cfu/sec, in the Wilson River; Figure 7). This was due to the
lower discharge values reached during the storm.
Samples were collected on only three occasions during Storm 3, a large storm that occurred in
March, 1997. A total of 4.5 in (12cm) of precipitation was recorded at Tillamook and this was added
to what were already highly saturated conditions throughout the watershed. This storm was not
originally scheduled to be sampled in this study. It was therefore sampled at a lower sampling
frequency than was typically employed for the storm sampling in this project, and the first sample
was not collected until 24 hours after the rainfall started. This storm was preceded by a very wet
period; rainfall had been recorded on seven of the previous eight days (Figure 8). Discharge in the
Wilson River was at 3,000 cfs at initiation of the storm, and had been near 5,000 cfs only two days
previously. Peak Wilson River discharge during the storm reached about:11,000 cfs, close to flood
stage and the highest of any storm sampled in this study. FCB concentrations were generally less
than 200 cfu/100 ml, except in the Tillamook River, which exhibited much higher concentrations
(-200 to 700 cfu/100 ml) (Figure 8). Peak loads were measured in the Trask River (-0.5 x 106
cfu/sec) on one sample occasion and in the Tillamook River (-0.25 x 10 6 cfu/sec) on one sample
occasion (Figure 9). Other measured loads were substantially lower.
The first storm that was sampled in an intensive fashion, both spatially and temporally, was
Storm 4, the first sizable storm of the fall season in 1997. It occurred during early October and
resulted in 6.5 in (17cm) of precipitation at Tillamook. Results for the primary sites on the Tillamook
and Trask Rivers are shown in Figure 10; results for other sites on these two rivers are shown in
subsequent sections of this report. E&S did not sample the other three rivers during Storm 4.
However, the Wilson River was sampled by TCCA, and the Kilchis and Miami Rivers were sampled
by ODEQ (data not shown). The fall storm was unique in a number of respects. Other than a very
small two-day rain event three to four days previously (which did not increase flows much, especially
Results of Storm Sampling in the Tillamook Bay Watershed
E&S Environmental Chemistry, Inc.
May, 1998
Page 21
Tillamook River
4.0
- 1.5
.tti
3.5
"a
3.0
2.5
o c,
2: co
2.0
V
1.5
(.)
0.0
21JAN97
Trask River
4.0
'C
a) _
c.) no
as
x
E
E
!•- 0
: 8.0
3.5 -;
r6.0 p x
e-•
x
as
4.0 v
(.)
2.0
3 .4
0 0-
I-
tt
0
LL
o
0.0 -= 7JAN97
0.0
r
1I
14JAN97
21JAN97
Figure 6. Concentration of fecal coliform bacteria (cfu/100 ml x 10 3), 6 hour precipitation totals
(scale variable by river), and river discharge (cfs x 10 3) at the primary monitoring sites on
each of the five rivers for the January 1997 storm.
Results of Storm Sampling in the Tillamook Bay Watershed
E&S Environmental Chemistry, Inc.
May, 1998 \
Page 22
Wilson River
4.0
CU
*L7
4.1
o
3.5
es m- 3.0=
03 X 2.5
E
E
0
2.0
1.5
S
soWS (3
1.0
0.5
Kilchis River
4.0 ea
.
3.5
4.0
3.0
c.)
%-
-
E
8
- 6
CD X
.c
X
2.5
4
2.0:
0 c,
1.5
o
1.0
0
-
c.)
2
0.5
at
•...,
1.5
3.5=
3.0 7:
vX
2'5
2.0
E
!'"' to
1.5
17
1.0
0
d
v
0.5
0.0
Figure 6. Continued.
o
132
Miami River
4.0
LL
0
7JAN97
C°
(i)
0.0
Results of Storm Sampling in the Tillamook Bay Watershed
E&S Environmental Chemistry, Inc.
May, 1998
Page 23
Tillamook River
1.50
as
o
ca
1.25
o
Ca
E
o
•
o
- 1.5
1.00 -
w 0.75
6 0.50 -
14
To
0.25
u.
0.00 L.
0.0
21JAN97
Trask River
- 8.0
1.50 03
1.25 - 6.0
4.5
O
CO
1.00
E x
0
0.75 -
as
o
".7.
o
0
_
- 4.0
0.50
- 2.0
0
0.25 L
w
u.
0.0
0.00 L. I
7JAN97
1
'
I
14JAN97
1
T
I
I
21JAN97
Figure 7. Load of fecal coliform bacteria (cfu/sec x 10 6), 6 hour precipitation totals (scale variable
by river), and river discharge (cfs x 10 3) at the primary monitoring sites on each of the
five rivers for the January 1997 storm.
Results of Storm Sampling in the Tillamook Bay Watershed
E&S Environmental Chemistry, Inc.
May, 1998
Page 24
Wilson River
1.50 -
2.7 •
- 8.0
ca
1.25
6.0
1.00 E
- 4.0
0.75
6
39
0t
6
c.)
a)
u-
0.50 2.0
0.25 7
0.
00
0.0
-
I
7JAN97
'
14JAN97
21JAN97
Kilchis River
1.50
ea
I .....
1.25
L
a,
co
1.00
E x
0.75
8
13
8
-6
0.50
as
0.2
0.00
-
7JAN97
14JAN97
Miami River
1.50 -
r.,a,
1.25
-_
1.0
-
- 1.5
-
0.755
:41C3.
o
0
as
6
0.50
0.25
L
0.0
21JAN97
Figure 7. Continued.
Results of Storm Sampling in the Tillamook Bay Watershed E&S Environmental Chemistry, Inc.
May, 1998
Page 25
Tillamook River
4.0
!a
▪
4.0
3.5
- 2.0
_
0 3.0
as
CO
•
E 1- E
o
2.5
2.0
Mr. C)
0
C.)
a
Ts
I-)
1.5
1.0
0.5
LL
0.0 =
0.0
22MAR97
Trask River
4 .0
ea
3.5 -
o
3.0 2:
%C3 X
2.5
E E
0 c)
2.0
0
ea
w
U-
12.0
-
•
O
•
-
8.0
X
-
1.5 1:
•
4.0
2.0
0.5
0.0 = r
15MAR97
•X
C
1MM
C
6.0 14O 0
1.0
8MAR97
in
7 10.0
g
T. '5
0.0
22MAR97
Figure 8. Concentration of fecal coliform bacteria (cfu/100 mi x 103), 6 hour precipitation totals
(scale variable by river), and river discharge (cfs x 10 3) at the primary monitoring sites on
each of the five rivers for the March 1997 storm.
Results of Storm Sampling in the Tillamook Bay Watershed E&S Environmental Chemistry, Inc.
May, 1998
Page 26
Wilson River
4.0 7:
CD
3.5
1
12
u
ca
•
E
•
0
6
3.0
x 2.5
E
"5
2.0
1.5 2:
1.0
0.5 2:
CD
0.0 2.
0.0
22MAR97
Kilchis River
4.0
•
- 12
3.5
-
v "c)
io
3.0
O
x
•
sou
c
0
2.5 2:
7
EE 2.0
0
6
1.5 7
O Z.:
1.0 2:
c.)
0.5 -I
o
▪
2
22MAR97
Miami River
4.0
co
-
3.0
3.5
c.)▪ '"'e
3.0 2:
Ca ; 2'5
E E 2.0 2:
7
o
co
•
O
rz
.2
c.)
1.5_
1.0
0.5
0.0 = 0.0
I
8MAR97
Figure 8. Continued.
c.)
ED.
o-
0
o
:1
▪ 46-
4
0
I
15MAR97
I
22MAR97
Results of Storm Sampling in the Tillamook Bay Watershed
E&S Environmental Chemistry, Inc.
May, 1998
Page 27
Tillamook River
1.50 -
2.0
R
• MIN
1.25
Ro
E
s
1.000.75 -
"c-, 0.50 Re
0.25 Li-
-
0.0
22MAR97
Trask River
•L•
1.25
w
v
ea f; 1.00 7
E x 0.75
•
0.50 -
0
-a
c.)
w
LL
0.25 0.00 8MAR97
15MAR97
0.0
22MAR97
Figure 9. Load of fecal coliform bacteria (cfu/sec x 10 6), 6 hour precipitation totals (scale variable
by river), and river discharge (cfs x 10 3) at the primary monitoring sites on each of the
five rivers for the March 1997 storm.
Results of Storm Sampling in the Tillamook Bay Watershed
E&S Environmental Chemistry, Inc.
May, 1998
Page 28
Wilson River
as
1.50 -
12.0
1.25 -
10.0
ca
1.00
8.0
0.75 -
6.0
X
(I) C
14o
0.50
4.0
g
0.25 -
2.0
E
O
C)
7ts
"
LI.. 0
a)
0.
U-
0.00 -
0.0
r
15MAR97
I
22MAR97
Kilchis River
1.50 ca
- 12
1.25 -
▪
a)
4.0
as
E
•
1.00
0 0.75 =
to
O
0.50
is
0.25 =
L
15MAR97
Miami River
= 3.0
1.50
63
*E--
0.)
1.25
12
E
7
1.00 =_
2.0
o --c
X 0
0.75
0
19
-
0.50
to 3
96
I
0.25
15MAR97
Figure 9. Continued.
pi
a
73
Results of Storm Sampling in the Tillamook Bay Watershed E&S Environmental Chemistry, Inc.
May, 1998
Page 29
Tillamook River
- 1.3
4.0
ett
ca
E
3.5
O
1.0
3.0
o
X 2.5
0
c:)
0 ▪
=
c.) 4o
co
0.8
X
•!
0
2.0
- 0.5
1.5
1.0-
0.3
0
a: /1-,
0.5 -
u-
0.0 23SEP97
30SEP97
0.0
Trask River
4.0
- 12.0
ca
3.5
- 10.0
cu „-.
3.0
x
8.0 v.- c
cu
2.5
E
E
0 0
-6 ‘-
x
2.0
6.0
1.5
4.0 3
1.0
a)
U-
o
2.0
0.5
.0
o
LT.
0
0.0
23SEP97
30SEP97
7OCT97
Figure 10. Concentration of fecal coliform bacteria (cfu/100 ml x 10 3 ), 6 hour precipitation totals
(scale variable by river), and river discharge (cfs x 10 3 ) at the primary monitoring sites on
the Tillamook and Trask Rivers for the October 1997 storm.
Results of Storm Sampling in the Tillamook Bay Watershed
E&S Environmental Chemistry, Inc. May, 1998
Page 30
in the larger rivers) and a moderate storm in mid-September, conditions had been dry for months
prior to the storm (Figure 1). In addition, this was a fairly large storm, even by winter-storm
standards. Discharge in the Wilson River reached nearly 9,000 cfs. The patterns of rainfall and
discharge were complex throughout the storm, with numerous short-lived lulls between periods of
relatively intense rain (Figure 10).
Two patterns of FCB response are observable in Figure 10. The majority of the measured FCB
concentrations followed a clear pattern of increasing concentration, to a peak after three days,
followed by decreasing concentrations. Peak FCB concentrations corresponded temporally with the
approximate mid-point (peak) of the precipitation inputs. The peak discharge occurred two days
later, when bacterial concentrations had already decreased to less than half of the peak FCB
concentrations. The second pattern of FCB response, evident in a closer look at the data points,
shows greater variability, with a series of rises and falls in FCB concentration, and these
corresponded roughly with the pulses of precipitation inputs, especially in the Tillamook River.
FCB concentrations achieved during the fall storm were very high, up to nearly 2,500 cfu/100
ml in the Trask River and over 3,500 cfu/100 ml in the Tillamook River. Similarly high
concentrations were recorded by TCCA in the Wilson River. FCB loads in the Trask River
exceeded 0.5 x 10 6 cfu/sec throughout much of the storm, with peak loads over 1.5 x 106 cfu/sec.
Peak loads in the Tillamook River were also high (by Tillamook River standards), in the range of 0.4
to 0.6 x 106 cfu/sec (Figure 11).
A storm of moderate size was sampled in mid-February, 1998. It raised discharge in the
Wilson River to about 5,000 cfs, and was actually the largest storm of the late winter and spring
seasons in 1998. It was preceded by a week of frequent rain showers and relatively constant
discharge (-500 to 700 cfs on the Wilson River; Figure 12) and contributed 5.4 in (14cm) of
precipitation at Tillamook. As was observed during the fall storm, FCB concentrations followed the
overall precipitation pattern relatively well, and peak discharge occurred one or two days later than
the peak FCB concentrations. Peak FCB concentrations reached about 500 cfu/100 ml in the
Tillamook River, slightly lower in the Trask River, and generally less than about 200 cfu/100 ml in
the other rivers. The Trask River achieved the highest loads, but these were only about 0.35 x 106
cfu/sec because neither the FCB concentration nor the discharge rate was particularly high (Figure
13).
The second intensively-sampled storm, and the last storm to be sampled during the 1998 highflow season, occurred in early March, 1998. It was preceded by a four day period of generally
decreasing discharge and little rainfall (Figure 14). The storm was moderate in size and increased
Wilson River discharge to over 3,500 cfs, from a pre-storm baseline of just over 1,000 cfs. A total of
4.3 in (11cm) of precipitation was recorded in Tillamook. This storm was unusual in that river
discharge increased to relatively high values during the first two days of the storm, and then
Results of Storm Sampling in the Tillamook Bay Watershed E&S Environmental Chemistry, Inc.
May, 1998
Page 31
Tillamook River
1.50 ea
1.25 0
co
co
E
x
1,_
o 0
'I. (I)
0
ars
"Fs
1.00 -
0.75
0.50
0.25 -_-
a)
u..
0.00
Trask River
- 12.0
1.50
-al
'C.
1.25 -
os
1.00 -
10.0
8.0 c)
X
E
o
0
0.75
6.0
0.50
4.0
=,
W
0 0
CD
To
u.
0.00.
.
2.0
0.25
0.00- 23SEP97
30SEP97
0.0
7OCT97
Figure 11. Load of fecal coliform bacteria (cfu/sec x 10 6), 6 hour precipitation totals (scale variable
by river), and river discharge (cfs x 103) at the primary monitoring sites on the Tillamook
and Trask Rivers for the October 1997 storm.
Results of Storm Sampling in the Tillamook Bay Watershed
E&S Environmental Chemistry, Inc. May, 1998
Page 32
Tillamook River
4.0
-
1.5
3.5
3.0 7:
2.5
2.0
1.5
1.0
0.5
0.0 -
0.0
31JAN98
14FEB98
Trask River
- 8.0
4.0
3.5
,—..
ea)
2.5
ca
—
oE
0
C.)
6.0
3.0
4.0
2.0
1 .5 --
a
-a 0
0
0
- 2.0
1. 0
0.5 7,
0.0=
31JAN98
0.0
1,,
7FEB98
14FEB98
Figure 12. Concentration of fecal coliform bacteria (cfu/100 ml x 10 3), 6 hour precipitation totals
(scale variable by river), and river discharge (cfs x 10 3) at the primary monitoring sites on
each of the five rivers for the February 1998 storm.
Results of Storm Sampling in the Tillamook Bay Watershed
E&S Environmental Chemistry, Inc.
May, 1998
Page 33
Wilson River
4.0 -7:
.cu
3.5
1)
C13
C)
3.0
x
2.5
E
E
o
2.0
1.5
o
(-)
CD
1.0
0.5
0.0
31JAN98
Kilchis River
8
4.0 ea
•3
L.
3.5-
vo
3.0 -
cu
x
6 o0
X
e-
2.5 -
XZr„..
E
2 LT-
LL
Miami River
CU
17.
- 1.0
3.5
3.0
as
E
0
0
Ca
C.)
a)
LL
2.5
2.0
- 0.5
1.5
1.0
0.5
0.0
0.0
14FEB98
Figure 12. Continued.
o
3 43
.11
r.
0 a 1.0 Its C')
0.5 a)
4.0
C
4
2.0
cs E
1.5 -
E.
Results of Storm Sampling in the Tillamook Bay Watershed
E&S Environmental Chemistry, Inc. May, 1998
Page 34
Tillamook River
1.50 7
.ca
a)•
4-6
1.25 7
as urs
o,
to
1.00 -
•
1.5
E
8
0
O 0.75 Mr. co
O
0.50 -0 146
u
a)
0.25 0.00 -
0.0
I
f
14FEB98
7FEB98
Trask River
- 8.0
1.50 -
ea
0
1 .25 -_
- 6.0
eva
1.00 -
ca
X
E
6. 0
o 0
"ez
•x
en
- 4.0 %-
0.75
:1.7.1
0
13
c.)
LL
0.50 -
- 2.0
0.25 -
0 .0.
c)
a)
1
0.0
0.00 -
i
31JAN98
1
7FEB98
f
I
14FEB98
Figure 13. Load of fecal coliform bacteria (cfu/sec x 10 6), 6 hour precipitation totals (scale variable
by river), and river discharge (cfs x 10 3) at the primary monitoring sites on each of the
five rivers for the February 1998 storm.
Results of Storm Sampling in the Tillamook Bay Watershed E&S Environmental Chemistry, Inc.
May, 1998
Page 35
Wilson River
1.50 -
rax
0
a)
co
=
is
0
o
u.
it
1.25 1.00 0.75
0.50 0.25 0.00 -
1
,
31JAN98
Kilchis River
8
Miami River
1.0
0.0
1
31JAN98
Figure 13. Continued.
14FEB98
Results of Storm Sampling in the Tillamook Bay Watershed
E&S Environmental Chemistry, Inc. ti
May, 1998
Page 36
Tillamook River
4.0 -
. ca
▪
3.5 7:
'ZD
cc „-
3.0
CO X 2.5
E—
E
o a,
2.0 ---_
co
O .1.7.
a
1.5
0
1.0
•
0.5
0.0
18FEB98
Trask River
- 8.0
4.0
3.5
*I-. 0--
o
as
CO
3.0
2.5
E
0 co
co
2.0
1.5
F
18FEB98
I
T
25FEB98
Figure 14. Concentration of fecal coliform bacteria (cfu/100 mi x 10 3 ), 6 hour precipitation totals
(scale variable by river), and river discharge (cfs x 10 3 ) at the primary monitoring sites on
the Tillamook and Trask Rivers for the March 1998 storm.
Results of Storm Sampling in the Tillamook Bay Watershed
E&S Environmental Chemistry, Inc.
May, 1998
Page 37
remained relatively constant for a two to three day period. Again, FCB concentrations generally
followed the precipitation pattern, reaching peak concentrations near 400 cfu/ 100 ml in the
Tillamook and 900 cfu/100 ml in the Trask River. FCB loads in the Trask River were relatively high,
reaching a measured peak of about 1 x 10 6 cfu/sec, with several measurements during the storm in
the range of 0.3 to 0.6 x 10 6 cfu/sec (Figure 15). Peak loads in the Tillamook River were low (just
over 0.1 x 10 6 cfu/sec).
Other Parameters
TSS concentrations were measured at the primary sites during the routine storms (Storms 1, 2,
3, 5). Results of TSS measurements during the four storms are presented in Figures 16 through 23.
Both TSS concentrations and loads were highly correlated with discharge throughout the duration of
the study (Sullivan et al. In review), and followed the pattern of storm discharge closely in each river
during each storm (Figures 16-23). Peak TSS concentrations were highest in the Wilson River
during each storm, reaching concentrations of about 500 mg/L during Storm 1 (Figure 16) and over
300 mg/L during Storm 3 (Figure 21). Peak TSS concentrations in the Trask River were only slightly
lower during the first storm (-450 mg/L) but less than 1/3 of the peak Wilson River value during the
third storm. The other rivers typically exhibited peak TSS concentrations that were only half or lower
those found in the Wilson River. Peak TSS loads exceeded 80 mg/sec in the Wilson and Trask
Rivers during Storm 1 (Figure 17). Peak loads in the Kilchis River were lower by more than a factor
of two, and peak loads in the Miami and Tillamook Rivers were lower by more than a factor of ten
(Figure 17).
Total inorganic nitrogen (TIN) concentrations did not change dramatically during the two storm
events in which they were measured (Figures 24, 25). There was often a general decrease in TIN
concentration near peak discharge, likely due to dilution. TIN loads increased with discharge during
the storms, however, reaching peak values over 200 mg/sec in the Trask and Wilson Rivers, about
100 mg/sec in the Kilchis River, and less than 50 mg/sec in the Miami and Tillamook Rivers (Figures
26, 27).
Total phosphorus (TP) was measured during two storms and showed a clear pattern of
increasing concentration with increasing discharge (Figure 28). Peak values were achieved during
Storm 1 in the Trask and Wilson Rivers (-0.8 and 0.6 mg/L, respectively). Lowest concentrations
during peak discharge periods (-0.2 mg/L) were achieved in the Miami and Tillamook Rivers, with
the Kilchis River being intermediate. TP loads also increased with discharge during Storm 1, an
increase of about an order of magnitude over pre-storm values in the Trask River and about two
orders of magnitude in the Wilson River (Figure 29). Somewhat lower concentrations and loads
were measured during Storm 2, although the general patterns of response were similar (Figures 30,
31).
Results of Storm Sampling in the Tillamook Bay Watershed
E&S Environmental Chemistry, Inc.
May, 1998
Page 38
Tillamook River
1 .50
.ca
- 1.5
1.25
493
wc:,
co ‘..n
1.0
E
I..
46
cv
c
P1
1.00
vx 0
0.75
CI) 74
0.50
0.5 3 '3
u
.15
o
0.25
0.00
0.0
4MAR98
Trask River
1 .50
1.25 7
a)
^
uiz,
03
- 8.0
v-
6.0
1.00
Ex
,t) 0.75
1-
0
6
0.50
- 2.0
0.25
as
Figure 15. Load of fecal coliform bacteria (cfu/sec x 10 3 ), 6 hour precipitation totals (scale variable
by river), and river discharge (cfs x 10 3 ) at the primary monitoring sites on the Tillamook
and Trask Rivers for the March 1998 storm.
Results of Storm Sampling in the Tillamook Bay Watershed
E&S Environmental Chemistry, Inc.
May, 1998
Page 39
Tillamook River
400.00
"1:1
a 300.00
as
o. E
200.00 =
cA
100.00
Trask River
:c.-11
400.00
73
_
0 300.00
al 0...
•
'a —I
c *El
o. E 200.00 -
(0 ••n•••
100.00
0.0
T
T
30NOV96
Figure 16. Concentration of total suspended solids (mg/L), 6 hour precipitation totals (scale variable
by river), and river discharge (cfs x 103) at the primary monitoring sites on each of the
five rivers for the December 1996 storm.
Results of Storm Sampling in the Tillamook Bay Watershed
E&S Environmental Chemistry, Inc. May, 1998
Page 40
Wilson River
•
500.00 400.00 -_
.• .-..
13
300 00 c --I11
a)
o. E
• --- 200.00 fn
100.00 -
o
0.0
Kilchis River
500.00 -
-
400.00 7
- 12
15
N
-6
U)
▪
-
a) .—. 300.00
9 X
C e,
&F.
•
-
E 200.00 -
6
0
A
O .0.
-
100.00 7
Aimilm•fillhoonammoi
0.00 -23NOV96
30NOV96
•
3 LI-
0
7DEC96
Miami River
500.00 400.00 -_
300.00 200.00 100.00 0.00 I
23NOV96
Figure 16. Continued.
1
30NOV96
1
1
I
7DEC96
a)
Results of Storm Sampling in the Tillamook Bay Watershed
E&S Environmental Chemistry, Inc. May, 1998
Page 41
Tillamook River
- 2.5
80 =
.C3
-6
(1) ^
70
6050-
o
40
CL CA
(I) "r7)
=
E
30 20 0.0
7DEC96
Trask River
0.0
7DEC96
Figure 17. Load of total suspended solids (mg/sec x 103), 6 hour precipitation totals (scale variable
by river), and river discharge (cfs x 10 3) at the primary monitoring sites on each of the
five rivers for the December 1996 storm.
Results of Storm Sampling in the Tillamook Bay Watershed
E&S Environmental Chemistry, Inc.
May, 1998
Page 42
Wilson River
80 70 1")
m "- 60 T50
X
C0
O 0 40
Q
a) 1-0 30 E 20
3O
10=
0=
N
:°
g
0.0
Kilchis River
80 7
70 :
60
CO
50 o
73
40=
C
O 0
CO 30 0
E 20 H
100
0=
23NOV96
- 15
4-- 12
9
"sb x
a
X
V) C
O
0
3 :5
Sir
_
3
O .0.
LL
30NOV96
Miami River
109:1:3
8-6
cnc 7
▪ 6=
0X
C v 5
• cp
o. co
4H
u)
3
cn
• E
2
FO
1H
0-
2.0
•.5
•x 0
a
1.5 "a
•
23NOV96
Figure 17. Continued.
1.0
- 0.5
0.0
7DEC96
42 trz
0
O a)
Results of Storm Sampling in the Tillamook Bay Watershed
E&S Environmental Chemistry, Inc.
May, 1998
Page 43
Tillamook River
to
7:3
Z
400.00 -
v)
ms
W ^
MS —I
300.00 -
c 6,
0.
0 ...- 200.00 -
m
u)
3
100.00 -
o
I--
1
7JAN97
1
14JAN97
Trask River
Figure 18. Concentration of total suspended solids (mg/L), 6 hour precipitation totals (scale variable
by river), and river discharge (cfs x 10 3) at the primary monitoring sites on each of the
five rivers for the January 1997 storm.
Results of Storm Sampling in the Tillamook Bay Watershed E&S Environmental Chemistry, Inc.
May, 1998
Page 44
Wilson River
:a
.7)
U)
400.00 -
•
.c.s a300.00
c'
•
=
200.00 100.00 7
I
14JAN97
Kilchis River
- 8
500.00 ca
-a
0
400.00
U)
1:3
4:8
6
o
300.00 7
x
c
X
4 4-
—J
C "en
c 200.00 -
(I) "--'"
cn
- 2 ° PLL •c.)
L.
100.00 -
43
0
0
0.00 7JAN97
I
14JAN97
r
0
T
21JAN97
Miami River
500.00 -a
-
1.5
400.00 7
▪
U)
-a
"a
C
300.00 -
E 200.00
---
100.00
0. 0
21JAN97
Figure 18. Continued.
Results of Storm Sampling in the Tillamook Bay Watershed
E&S Environmental Chemistry, Inc. May, 1998
Page 45
Tillamook River
80 -
- 1.5
(I)
.
43
70 -
-6
to ^
o
"cs v-
X
C
CD 0
fa. co
""`
=
fn E
3
O
60 -
1.0 a
50
0
7-1
o :01
40 30 -
- 0.5 3 '5
o a)
20 -
a. t
10
I I
0 7JAN97
14JAN97
0.0
21JAN97
Trask River
80
8.0
N
70
-c3
60 =.
6.0 06
e-
c0
50-
•
-0
C 0
CD di
O. CA
u)
• sa
cf) E
0
X
4.0
40 -
30 -
- 2.0
20 -
o
3
o
a)
10 0.0
o7JAN97
CA g
*0
14JAN97
21JAN97
Figure 19. Load of total suspended solids (mg/sec x 10 3), 6 hour precipitation totals (scale variable
by river), and river discharge (cfs x 10 3) at the primary monitoring sites on each of the
five rivers for the January 1997 storm.
Results of Storm Sampling in the Tillamook Bay Watershed
E&S Environmental Chemistry, Inc.
May, 1998
Page 46
Wilson River
0
o
x
x
c
0
0
.0-
LL
0
Kilchis River
80
8
70
O
x
c 0
(1)
O. U)
60
50=
40
-co
cn E
302
0
10
20
o=
7JAN97
Miami River
0.0
I
7JAN97
Figure 19. Continued.
I
14JAN97
I
21JAN97
Results of Storm Sampling in the Tillamook Bay Watershed
E&S Environmental Chemistry, Inc.
May, 1998
Page 47
Tillamook River
U)
400.00 -_
.5
-o
c
--- 300.00 -
c
-..t.
(19
=
(/)
3
x
O
1.;
200.00 -
3 '5
ow
100.00 -_
Trask River
U)
400.00
-6
(/)
1:11
a)
ca)
300.00
-J
o. E
th
200.00 -
U)
100.00 0
0.0
Figure 20. Concentration of total suspended solids (mg/L), 6 hour precipitation totals (scale variable
by river), and river discharge (cfs x 10 3) at the primary monitoring sites on each of the
five rivers for the March 1997 storm.
Results of Storm Sampling in the Tillamook Bay Watershed
E&S Environmental Chemistry, Inc.
May, 1998
Page 48
Wilson River
O
U)
–1
c -a,
o. E
•
300.00 200.00
100.00 -
H
Kilchis River
- 12
- 10
500.00 -_
400.00 7
- 8
300.00 -
v-
6 • c
C.3 0
200.00 -
4
O .0.w
100.00 -
:
2
LL'
01:
0
0.00 8MAR97
15MAR97
Miami River
500.00
400.00
O
1:1
'0
•
- 3.0
300.00
6)
o. E
U)
0.0
Figure 20. Continued.
Results of Storm Sampling in the Tillamook Bay Watershed
E&S Environmental Chemistry, Inc.
May, 1998
Page 49
Tillamook River
- 2.0
Ca
70
60_-
cn
-a
o
-cs
50
•o. en
40
a) a)
Irs)
U) E
7ei
- 1.5 ^
C
x 0
1.0
co 4..-,.
4o
a
li
3 73
0.5 o a)
30 20
• 6:
10 H.
0-
0.0
22MAR97
Trask River
80 70 H.:
:0
60
cr)
Tx
50
40-
C.)
tD CD
O. co
30
E
20
0.0
22MAR97
Figure 21. Load of total suspended solids (mg/sec x 10 3), 6 hour precipitation totals (scale variable
by river), and river discharge (cfs x 10 3) at the primary monitoring sites on each of the
five rivers for the March 1997 storm.
Results of Storm Sampling in the Tillamook Bay Watershed E&S Environmental Chemistry, Inc.
May, 1998
Page 50
Wilson River
Kilchis River
- 12
80 -
70
.C3
-
CI)
_
50
-0
x
c
a) a)
CO
10
60
U)
30
E
20 =
0
viz X
T- c
6
4-,
X =.
40 7
-6)
8
4
-
10
2
CA
c
0 .0
3 7-0:
0 .C2LL 0
2).
CL
0
0
T
8MAR97
15MAR97
22MAR97
Miami River
- 3.0
10 en
'o
9=
CO
7-
'CI
113
-0 X
C 0
6
5
a) a)
0- en
• •E
2.0
a
7
X0
=
CI)
4
3=
=
1.0
2
0
0.0
0=
8MAR97
Figure 21. Continued.
15MAR97
22MAR97
0
:11:
1.3
6:
May, 1998
Page 51
Results of Storm Sampling in the Tillamook Bay Watershed E&S Environmental Chemistry, Inc.
Tillamook River
-
400.00
0
-_
C13
^ 300 00 -
c -a)
o.
E 200.00 •
=
0
31JAN98
Trask River
500.00 -_
8.0
—
7
400.00 0
- 6.0
-
7,
-cs
300.00 -
-.1
4.0
c
a)
• E 200.00 3
0
2.0
100.00
0.0
0.00 - 1
31JAN98
1
I
7FEB98
r
T
7
1
1
14FEB98
Figure 22. Concentration of total suspended solids (mg/L), 6 hour precipitation totals (scale variable
by river), and river discharge (cfs x 103) at the primary monitoring sites on each of the
five rivers for the February 1998 storm.
Results of Storm Sampling in the Tillamook Bay Watershed
E&S Environmental Chemistry, Inc. May, 1998
Page 52
Wilson River
Kilchis River
-.125
400.00
-6
'a -.I
C
Q
y
300.00
as
E 200.00
100.00
0
I
V
7FEB98
Miami River
500.00 O
-1
c C)
cu
-
1. 0
400.00
300 • 00
-
- 0.5
•co E 200.00 •
100.00 0 .00 --
Figure 22. Continued.
0. 0
Results of Storm Sampling in the Tillamook Bay Watershed
E&S Environmental Chemistry, Inc.
May, 1998
Page 53
Tillamook River
80
N
0
g
-a ye
-0 X
a)
c.)
0. av)
CI)
cn
(/) E
--
70
60
50
40 H
30
20
10
0
- 1.5
31JAN98
II .
I
.
7FEB98
•
0.0
14FEB98
Trask River
:cs
6
"a)0
v-
80
70
60 -_50
-0 x
C o 40
- 8.0
- 6.0 o
X
- 4.0 4-
x
c
ID
N. 30 =
(/)
0
Cn
E
20 -10
0
o
- 2.0 c.c..
00.
0.0
Figure 23. Load of total suspended solids (mg/sec x 103 ), 6 hour precipitation totals (scale variable
by river), and river discharge (cfs x 10 3 ) at the primary monitoring sites on each of the
five rivers for the February 1998 storm.
Results of Storm Sampling in the Tillamook Bay Watershed
E&S Environmental Chemistry, Inc.
May, 1998
Page 54
Wilson River
80 -
N
70=
-6
No 60
"a
13 X
C 0
O
CD
Zn
NE
30
50
40=
30 20
10
0=
Kilchis River
80 co
70
-6
60 -
co ^
50
-0 )4
c v
O. CO
en
a)
- 8
0
6
v-
"cp
=
40_
4
O
=
0
30=
O .0.
2 LL()
a)
0
Miami River
co
109
1.0
8
▪ X'
U)
7
13
•X
6H
5
c)
• cO
0. CO
• cr)
cn E
4
3=
2
1=
0- I
31JAN98
Figure 23. Continued.
7FEB98
0.0
14FEB98
Results of Storm Sampling in the Tillamook Bay Watershed
E&S Environmental Chemistry, Inc. May, 1998
Page 55
Tillamook River
1 .8 -
2.5
1.6
2.0
1.4
1.2 ;
+
•-
1.5 x
1.0
0.8
z
a
e-.
-
1.0
0.6
0.4
7
0
4-z
o35
0.5 5:
0:
0.2 ;
0.0
0.0 -
1
I
23NOV96
'
30NOV96
7DEC96
Trask River
- 15.0
1.8
4--
1.6
4
- 12.0
1.4
ID
v-
1.2 ;
+ a
-
1.0 =,
9.0 x
O
Z:1) 0.8=
E
0.6 7:
-
C
0
6.0
O .0.
0.4
3.0
LL
0C1
0.2
0.0
0.0 -I-
23NOV96
I
30NOV96
7DEC96
Figure 24. Concentration of total inorganic nitrogen (mg/L), 6 hour precipitation totals (scale
variable by river), and river discharge (cfs x 10 3 ) at the primary monitoring sites on each
of the five rivers for the December 1996 storm.
May, 1998
Page 56
Results of Storm Sampling in the Tillamook Bay Watershed E&S Environmental Chemistry, Inc.
Wilson River
1.8 7
1.6
12.0
1.4 7:
z
+a
1.2
Z
0.6
Z
0.4
co
c.)
6.0
o
.471
O .0.
3.0 U-
0.2 7
2!
0
0.0
0.0
23NOV96
x
9.0 x '=
1.0
E 0.8
0
o
30NOV96
Kilchis River
- 15
1.8 1.6 -
12
1.4 -
na
1.2 -
9 X
1.0
44.•
O
0.8 -
3 :116
o
3 u-
0.4 0.2 -
0
0.0 30NOV96
7DEC96
Miami River
1.8 -
2.0
1.6
1.4 -
1.5
1.2 1.0 -
1.0
0.8 0.6 0.4 -
0.5
0.2 0.0 23NOV96
Figure 24. Continued.
C
.0
6
0.6 -
23NOV96
x
0.0
2!
Results of Storm Sampling in the Tillamook Bay Watershed
E&S Environmental Chemistry, Inc. May, 1998
Page 57
Tillamook River
1.8 1.6
1.4
1.2
1.0
+
2.0
0.8
•
0.6
0.4 0.2
0 .0 8MAR97
1
1
1
1
1
I
•
0.0
1
15MAR97
22MAR97
Trask River
1.8 -
12.0
1.6
1.4
1.2
10.0
-
0
o x
•
8.0
1.0
8)
- 6.0 "11
0 0
0.8 -
-=- 0.6
Z
0.4
.2 0.0 - O
- 4.0 o 311
u. o
- 2.0
0
8MAR97
15MAR97
0.0
22MAR97
Figure 25. Concentration of total inorganic nitrogen (mg/L), 6 hour precipitation totals (scale
variable by river), and river discharge (cfs x 10 3) at the primary monitoring sites on each
of the five rivers for the March 1997 storm.
Results of Storm Sampling in the Tillamook Bay Watershed E&S Environmental Chemistry, Inc.
May, 1998
Page 58
Wilson River
1.8 1.6
1.4 =
1.2
+
1.0
6.0
0.8
Z
0.6
Z 0.4
0.2
0 .0 -
Kilchis River
1 .8 -
- 12
1.6
- 10
1.4
1.2
+ j
-44
0
E
-
8
O
x
x =.
1.0 7
0.8 -_
0.6 =
-
6
-
4
•
O
.•44
O .0-
0.4
a. 2
0.2
a.
0.0 =
8MAR97
15MAR97
Miami River
3.0
1.8
1.6 7
1.4
1.2 =
1.0 -_
0 .8 0.6
0.4 =
0.2 =_
0.0
8MAR97
Figure 25. Continued.
0.0
15MAR97
22MAR97
Results of Storm Sampling in the Tillamook Bay Watershed
E&S Environmental Chemistry, Inc. May, 1998
Page 59
Tillamook River
Trask River
400
15.0
- 12.0
300
Z
+0
Z
- 9.0 x =.
U) c
0 .0
200
D)
0 E
z
z
-
6.0
-
3.0
loo -
023NOV96
a)
0.0
30NOV96
7DEC96
Figure 26. Load of total inorganic nitrogen (mg/sec), 6 hour precipitation totals (scale variable by
river), and river discharge (cfs x 103) at the primary monitoring sites on each of the five
rivers for the December 1996 storm.
Results of Storm Sampling in the Tillamook Bay Watershed
E&S Environmental Chemistry, Inc.
May, 1998
Page 60
Wilson River
Kilchis River
x
3
o
LL
c
ha
0
Miami River
400 -
Z
200 Z
100 -
023NOV96
Figure 26. Continued.
15
- 12
300
0
z
z
I-
-
bad
Results of Storm Sampling in the Tillamook Bay Watershed
E&S Environmental Chemistry, Inc. May, 1998
Page 61
Tillamook River
Trask River
300 ±*
Z
+ 0 200 Z
la
0E
z
100-
I-
0.0
1 15MAR97
Figure 27. Load of total inorganic nitrogen (mg/sec), 6 hour precipitation totals (scale variable by
river), and river discharge (cfs x 10 3) at the primary monitoring sites on each of the five
rivers for the March 1997 storm.
Results of Storm Sampling in the Tillamook Bay Watershed
EBBS Environmental Chemistry, Inc.
May, 1998
Page 62
Wilson River
0.0
15MAR97
Kilchis River
Miami River
Figure 27. Continued.
22MAR97
Results of Storm Sampling in the Tillamook Bay Watershed
E&S Environmental Chemistry, Inc.
May, 1998
Page 63
Tillamook River
0.80
-
2.5
- 2.0
C
CI • ""
-
1.5
xg
a
th
7 1.0
3 73
o co
7 0.5
0.0
'
30NOV96
7DEC96
Trask River
0.0
23NOV96
Figure 28. Concentration of total phosphorus (mg/L), 6 hour precipitation totals (scale variable by
river), and river discharge (cfs x 10 3 ) at the primary monitoring sites on each of the five
rivers for the December 1996 storm.
May, 1998
Page 64
Results of Storm Sampling in the Tillamook Bay Watershed E&S Environmental Chemistry, Inc.
Wilson River
• 0.96
0.80
cn
- 15.0
0.60
0
.c
o
•
0)
0.40
E
0.20
0.00
23NOV96
7DEC96
30NOV96
Kilchis River
0.80 -
- 15
-
12
o
9
x
0.60
E
CO
•
0.40 -
0
0
x
c
6
0.20
o
1—
3
0 .0.
U. 0
0
0
0.00 23NOV96
30NOV96
7DEC96
Miami River
0
0. 2
(1)
o
0.40
E
0.20
0.00 - 23NOV96
Figure 28 Continued.
0.0
I
I
30NOV96
7DEC96
Results of Storm Sampling in the Tillamook Bay Watershed
E&S Environmental Chemistry, Inc. May, 1998
Page 65
Tillamook River
0.80 -
E.
0
.c
0.60 -
o a) 0.40
E
0.20
7
Trask River
0.0
8MAR97
15MAR97
22MAR97
Figure 29. Concentration of total phosphorus (mg/L), 6 hour precipitation totals (scale variable by
river), and river discharge (cfs x 10 3) at the primary monitoring sites on each of the five
rivers for the March 1997 storm.
Results of Storm Sampling in the Tillamook Bay Watershed E&S Environmental Chemistry, Inc.
Wilson River
Kilchis River
Miami River
Figure 29 Continued.
May, 1998
Page 66
May, 1998
Page 67
Results of Storm Sampling in the Tillamook Bay Watershed ES'S Environmental Chemistry, Inc.
Tillamook River
Trask River
- 15.0
200
Go
=
0
lb
x
e— C
12.0 ,
150
6
9.0 X
.c
0.-c;
a)
84
.c 0
a. ...E
0
=••
•
CD c
IF.
100 -
O .0
6.0 _
%
O
50 -
3.0 Li"
I—
.CL
Cj
EL)
.
a.
0
i
23NOV96
'
,
I
,
30NOV96
I
1
0.0
7DEC96
Figure 30. Load of total phosphorus (mg/sec), 6 hour precipitation totals (scale variable by river),
and river discharge (cfs x 10 3) at the primary monitoring sites on each of the five rivers
for the December 1996 storm.
Results of Storm Sampling in the Tillamook Bay Watershed
E&S Environmental Chemistry, Inc.
May, 1998
Page 68
Wilson River
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Figure 30 Continued.
'
'
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Results of Storm Sampling in the Tillamook Bay Watershed
E&S Environmental Chemistry, Inc. May, 1998
Page 69
Tillamook River
200
Trask River
0.0
8MAR97
15MAR97
22MAR97
Figure 31. Load of total phosphorus (mg/sec), 6 hour precipitation totals (scale variable by river),
and river discharge (cfs x 10 3) at the primary monitoring sites on each of the five rivers
for the March 1997 storm.
Results of Storm Sampling in the Tillamook Bay Watershed
E&S Environmental Chemistry, Inc.
May, 1998
Page 70
Wilson River
Kilchis River
Miami River
I
8MAR97
Figure 31 Continued.
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,
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15MAR97
.
i
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Results of Storm Sampling in the Tillamook Bay Watershed E&S Environmental Chemistry, Inc.
May, 1998
Page 71
Results of Load Calculations
The calculated storm hydrographs at the primary sampling sites were partitioned into
segments, based on the various sample occasions. For each segment, average FCB concentration
was calculated from the measured values at the leading and trailing ends of that time segment. The
average FCB concentration in each segment was then multiplied by the total discharge during that
time period to yield a calculated load. Professional judgement and the observed concentrations of
FCB during baseflow periods (Sullivan et al. in review) were used where necessary to estimate FCB
concentrations prior to the first sample collected and subsequent to the last sample collected during
each storm. The individual loads for each time segment were then added together to yield an
estimate of the total FCB load for each storm. Results of these storm load calculations are
summarized in Table 3.
The largest loads were contributed during the early fall storm in 1997 (Storm 4). Measured
loads during this storm in the Tillamook and Trask Rivers were more than twice as high as for any
other sampled storm (Similar results were found by TCCA for the Wilson River; data not shown).
The smallest loads were contributed by the smallest storm (4.3 in precipitation), which occurred in
the spring of 1998 (Storm 6, Table 3).
First approximation estimates of total annual loads of TSS, TIN, and TP were derived by
multiplying the flow-weighted average of the concentrations measured throughout the study
multiplied by the total annual discharge for the 1997 water year (October 1, 1996 - September 30,
1997). Results of these calculations are presented in Table 4.
Annual loads of FCB from each river were estimated in two ways. The first, and simplest, was
based on the measured flow-weighted concentration of FCB, as was done for the other variables.
However, because bacterial sampling in this project was skewed towards storm-sampling
Table 4.
First approximation estimate of annual water volume and load of TSS, TIN, TP, and
FCB in each of the five rivers that flow into Tillamook Bay.
FIRST APPROXIMATION ESTIMATE OF ANNUAL LOAD
River
Water
TIN
Volume
TSS
TP
(m3 x 10 12 ) (kg x 10 6 ) (kg x 10 3 ) (kg x 103)
FCB (cfu x 1012)
Based on Flow-weighted
Average Concentration
Based on Storm
Load Calculations
278
10
223
31
1,623
793
Trask
1,349
185
1,132
341
3,189
2,031
Wilson
1,362
314
832
710
2,065
-
Kilchis
668
49
496
144
238
-
Miami
273
15
259
41
339
-
Tillamook
Results of Storm Sampling in the Tillamook Bay Watershed E&S Environmental Chemistry, Inc.
May, 1998
Page 72
(especially during rising hydrographs) and because FCB concentrations exhibited such pronounced
variability in response to season, antecedent moisture conditions and rainfall intensity patterns, it
was anticipated that this method would likely yield an overestimate of the total annual load of FCB.
An alternative method was therefore also applied to estimate the annual load of FCB. In this second
approach, the storm-based load estimates, which are also presented in Table 3, were used in
conjunction with the observed hydrograph to estimate the storm load for each storm during the 1997
water year. Each storm was assigned the load equal to one of the monitored storms. We only used
results from 5 of the monitored storms in this calculation, because Storm 3 was judged to have
inadequate data. These storm load estimates were summed to provide the estimate of annual load.
The cumulative loading during the low flow season was judged to be too small to contribute
significantly to the final annual load estimate, and was therefore ignored for this calculation. Loads
were estimated in this way for the Tillamook and Trask Rivers, the two rivers for which we had
significant data on individual storm loads. Results of these calculations, as expected, were lower
than the estimates based on flow-weighted average concentration of FCB on all sampling occasions
(Table 4). The estimates differed by only about 50% for the Trask River (3,189 x 10 12 cfu versus
2,031 x 10 12 cfu), but about 100% for the Tillamook River (1,623 x 10 12 cfu versus 793 x 10 12 cfu,
Table 4).
DISCUSSION
The bacterial fluxes measured at each site on the Tillamook River throughout the duration of
the first intensive monitoring effort (Storm 4) are shown sequentially in Figure 32. Data are
presented from river mile (RM) 10.0 at the Yellow Fir Rd bridge crossing (top panel) downriver to
RM 0.9, at the last bridge crossing on the Tillamook River, near where it
eaters the bay. FCB loads
in the Tillamook River during the October, 1997 storm showed pronounced variability among sample
occasions at a given site and among sites within a given time period (Figure 32). However, FCB
loads were uniformly low at all sites (less than about 0.1 x 10 6 cfu/sec) on the first sample occasion
of the storm and again on the last sample occasion of the storm. Loads at several of the sites
increased as much as ten-fold or more at various times during the storm, especially on days 2
through 4 (October 1-3).
There were two peaks in FCB load at the uppermost site (RM 10) and these same peaks plus
an additional peak in FCB load at the next downriver site (RM 8.1). These three peaks in FCB load
at the Yellow Fir Rd and rest area sampling sites corresponded temporally with the pulses of
precipitation measured in the watershed (Figure 32). At the downriver sites, from RM 2.6 to RM 0.9,
the FCB loads showed relatively smooth patterns; the consistent exception to this occurred on
October 3', when FCB loads decreased markedly at all five of these sites. This time period
Results of Storm Sampling in the Tillamook Bay Watershed
E&S Environmental Chemistry, Inc.
May, 1998
Page 73
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30SEP97 1 OCT97 2OCT97 3OCT97 4OCT97 5OCT97 6OCT97 7OCT97
Date
Figure 32. Load of fecal coliform bacteria (cfu/sec x 10 6) at all sites measured along the mainstem
Tillamook River during the October 1997 storm. Sites are indicated by river mile (RM),
with the uppermost panel (RM 10) being at the Yellow Fir Rd bridge crossing and the
lowermost panel (RM 0.9) being at the last bridge before the Tillamook River enters the
bay. Also shown are the hourly precipitation amounts and the discharge throughout the
storm at the primary monitoring site.
Results of Storm Sampling in the Tillamook Bay Watershed
EBBS Environmental Chemistry, Inc.
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Page 74
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30SEP97 1 OCT97 2OCT97 3OCT97 4OCT97 5OCT97 6OCT97 7OCT97
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Figure 32. Continued.
May, 1998
Page 75
Results of Storm Sampling in the Tillamook Bay Watershed E&S Environmental Chemistry, Inc.
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Figure 32 Continued.
May, 1998
Page 76
Results of Storm Sampling in the Tillamook Bay Watershed E&S Environmental Chemistry, Inc.
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30SEP97 1 OCT97 2OCT97 3OCT97 4OCT97 5OCT97 6OCT97 7OCT97
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Results of Storm Sampling in the Tillamook Bay Watershed E&S Environmental Chemistry, Inc.
May, 1998
Page 77
corresponded to a rather significant lull that occurred in precipitation inputs (even though discharge
was actually increasing at that time). The largest loads were frequently at the rest area and in the
mid-section of the river between RM 2.9 and RM 5.5.
The bacterial fluxes measured at each site on the Tillamook River throughout the duration of
the second intensive monitoring effort (Storm 6) are shown sequentially in Figure 33. At the
uppermost site (RM 10), the FCB load remained low throughout the storm. FCB concentrations
were actually relatively high at this site (generally above 200 cfu/100 ml and as high as 1300 cfu/100
ml on one sampling occasion during this storm), but the discharge is low at the Yellow Fir Rd site,
only about 9% of the discharge at the primary site on this river. The various panels shown in Figure
33, as you move down to RM 4.5, show some areas with load increases (e.g., RM 8.1, 6.8 and 4.5),
but the changes from site to site were small relative to the changes throughout the storm at a given
site. The highest loads (> 0.25 x 10 6 cfu/sec) were observed in the lower reaches of the river, for
example at sites RM 2.0, 1.5, and 1.1. The most downriver site (RM 0.9) did not exhibit the high
peaks seen at a few of the other sites (e.g., > 0.5 x 10 6 cfu/sec at RM 1.5 and 1.1), but it had
substantially higher loads throughout almost the entire storm than did any of the upper sites. The
exception to this was very early in the storm, when some of the upper sites exhibited somewhat
higher loads than did RM 0.9. This pattern observed in the Tillamook River suggests that the major
sources of FCB load are many and that they are scattered throughout the agricultural portions of the
basin. However, largest loads were often reached in the mid-section of the Tillamook River during
the October storm and in the lower 2 miles of /he river during both storms.
FCB concentrations and loads were also measured in two tributary streams to the Tillamook
River that flow into it near the rest area at about RM 8 to 8.3. Some measurements were taken
during the first intensive storm (Storm 4) and additional measurements were taken during the last
storm (Figures 34 through 37). The concentration of FCB was generally low in Simmons Creek
during the October 1997 storm. On most sample occasions the concentration was less than 100
cfu/100 ml, although one high value (>600 cfu/100 ml) was measured (Figure 34). The FCB load in
Simmons Creek was always low (<0.05 cfu/sec). In contrast, the other tributary stream to the
Tillamook River that was sampled during the October 1997 storm (Fawcett Creek) contained quite
high concentrations of FCB. Concentrations were generally >500 cfu/100 ml and exceeded 2,000
cfu/100 ml on two sample occasions (Figure 35). Nevertheless, the discharge rate for Fawcett
Creek is relatively modest, and the FCB loads were well under 0.25 x 10 6 cfu/sec throughout the fall
storm (Figure 35). FCB concentrations in both of these tributaries during the March 1998 storm
were consistently less than 200 cfu/100 ml and were generally less than 100 cfu/100 ml. FCB loads
were very low (< 0.1 x 106 cfu/sec). Thus, these tributaries were not important contributors to the
observed high FCB loads in the Tillamook River during the spring intensive storm, although Fawcett
Creek was a significant contributor to Tillamook River loads during the fall storm.
Results of Storm Sampling in the Tillamook Bay Watershed
E&S Environmental Chemistry, Inc. May, 1998
Page 78
0.25 -
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Figure 33. Load of fecal coliform bacteria (cfu/sec x 106 ) at all sites measured along the mainstem
Tillamook River during the March 1998 storm.
6-O
Results of Storm Sampling in the Tillamook Bay Watershed
E&S Environmental Chemistry, Inc. May, 1998
Page 79
0.25 -
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Page 80
Results of Storm Sampling in the Tillamook Bay Watershed
E&S Environmental Chemistry, Inc.
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Results of Storm Sampling in the Tillamook Bay Watershed
E&S Environmental Chemistry, Inc.
May, 1998
Page 81
Simmons Creek
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Figure 34. Fecal coliform bacteria concentration (top panel) and load (bottom panel) in Simmons
Creek, at its point of entry into the Tillamook River, during the October 1997 storm.
Results of Storm Sampling in the Tillamook Bay Watershed
E&S Environmental Chemistry, Inc.
May, 1998
Page 82
Fawcett Creek
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Figure 35. Fecal coliform bacteria concentration (top panel) and load (bottom panel) in Fawcett
Creek, at its point of entry into the Tillamook River, during the October 1997 storm.
Results of Storm Sampling in the Tillamook Bay Watershed E&S Environmental Chemistry, Inc.
May, 1998
Page 83
Simmons Creek
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Figure 36. Fecal coliform bacteria concentration (top panel) and load (bottom panel) in Simmons
Creek, at its point of entry into the Tillamook River, during the March 1998 storm.
Results of Storm Sampling in the Tillamook Bay Watershed
E&S Environmental Chemistry, Inc. May, 1998
Page 84
Fawcett Creek
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Figure 37. Fecal coliform bacteria concentration (top panel) and load (bottom panel) in Fawcett
Creek, at its point of entry into the Tillamook River, during the March 1998 storm.
Results of Storm Sampling in the Tillamook Bay Watershed
E&S Environmental Chemistry, Inc.
May, 1998
Page 85
In the Trask River, the FCB loads during the October storm were highly variable from site to
site, and among sampling occasions at all except one of the sites. At the uppermost site (Loren's
Landing, RM 9.0), FCB loads remained relatively constant and and low (less than about 0.25 x 106
cfu/sec). All other sites showed pronounced variability during the course of the storm. All sites
exhibited relatively low loads (less than about 0.25 x 10 6 cfu/sec) on the first day of sampling
(September 30 or October 1) and again on the last day of sampling (October 6). Loads at most of
the sites exceeded 1 x 10 6 cfu/sec during portions of the storm, however, especially around the time
of the most intense rainfall (October 4 th). Two sites in the mid-section of the study area exhibited
loads in excess of 1.5 x 10 6 cfu/sec, at RM 4.3 and 3.7. All three of the lowest sites (RM 1.2, 0.2
and 0.0) exhibited loads greater than 2 x 10 6 cfu/sec. At RM 0.0, a fairly smooth response was
found, with gradually increasing loads throughout the course of the storm, to a peak of over 2 x 106
cfu/sec on October 4th, and then a decreasing load to about 0.25 x 10 6 cfu/sec on October 6th , the
last day of sampling (Figure 38).
FCB loads at the sampling sites on the Trask River during the March 1998 storm (Storm 6) are
shown sequentially in Figure 39. At the uppermost site (RM 9.0, Loren's Landing), FCB loads
remained very low throughout the storm (less than about 0.025 x 10 6 cfu/sec). At RM 7.0, the next
downriver site, a small increase in FCB load was observed early in the storm, but the FCB load at
this site remained below about 0.05 x 10 6 cfu/sec. The first site to show significant increases in FCB
flux during the storm was at RM 4.3, where FCB loads increased markedly on the second day of
sampling (February 28, 1998), and gradually decreased to near the pre-storm baseline over the next
three days. Several high peaks in FCB load (>0.25 x 106 cfu/sec) were observed at RM 3.7, and
these occurred slightly after the major pulses of precipitation. From site RM 3.6 down to site RM
2.4, there were rather small differences from site to site, except for one high peak measured at site
RM 3.2. The largest loads found in the Trask River during this storm were often observed at the six
lowest sites, from RM 2.3 to RM 0.0. At all six of these sites, FCB loads reached peak values
around 0.5 x 10 6 cfu/sec. At several of the lowest sites, FCB loads remained between about 0.25
and 0.50 x 106 cfu/sec throughout much of the duration of the storm. Sampling of the March 1998
storm was discontinued while the discharge was still relatively high in both rivers. In fact, there was
no peak discharge during this storm, but rather a plateau of elevated discharge. At the time of
cessation of sampling, FCB loads in the upper portions of the sampling area on the Trask River had
declined to near pre-storm levels. In the lower reaches of the Trask River (RM 1.7 and below),
however, FCB loads were still high (-0.5 x 10 6 cfu/sec) on the last sampling occasion.
The principal sites on the Tillamook and Trask Rivers that contributed FCB loads to the
respective rivers during the October 1997 storm are listed in Tables 5 and 6. The major load
contributing sites (compared to their neighboring upriver sites) on the Tillamook River were
scattered across much of the portion of the basin (lowlands) that was sampled. High load
Results of Storm Sampling in the Tillamook Bay Watershed
E&S Environmental Chemistry, Inc.
0-
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May, 1998
Page 86
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30SEP97 1 OCT97 2OCT97 3OCT97 4OCT97 5OCT97 6OCT97 7OCT97
Date
Figure 38. Load of fecal coliform bacteria (cfu/sec x 10 6 ) at all sites measured along the Trask River
during the October 1997 storm.
1=
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Results of Storm Sampling in the Tillamook Bay Watershed
E&S Environmental Chemistry, Inc. May, 1998
Page 87
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Results of Storm Sampling in the Tillamook Bay Watershed
E&S Environmental Chemistry, Inc. 1
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Figure 38 Continued.
Results of Storm Sampling in the Tillamook Bay Watershed
E&S Environmental Chemistry, Inc. May, 1998
Page 89
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Results of Storm Sampling in the Tillamook Bay Watershed
E&S Environmental Chemistry, Inc.
May, 1998
Page 90
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Figure 39. Load of fecal coliform bacteria (cfu/sec x 10 6) at all sites measured along the Trask River
during the March 1998 storm.
-c
Results of Storm Sampling in the Tillamook Bay Watershed E&S Environmental Chemistry, Inc.
May, 1998
Page 91
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Results of Storm Sampling in the Tillamook Bay Watershed
E&S Environmental Chemistry, Inc.
May, 1998
Page 92
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May, 1998
Page 93
Results of Storm Sampling in the Tillamook Bay Watershed E&S Environmental Chemistry, Inc.
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Results of Storm Sampling in the Tillamook Bay Watershed
E&S Environmental Chemistry, Inc. Table 5.
May, 1998
Page 94
Rank order bacteria load contributions at specific monitoring sites sampled 7 or more
times on the Tillamook River during all 12-hr time slices for which 6 or more sites were
sampled during the October 1997 storm. The top five load contributing sites are listed.
Ordered by Load'
Ordered by Load Per
Contributing Area 2
Ordered by Load Per River
Miles to Upriver Site3
Site
R.M.
Total Score
Site
R.M.
Total Score
Site
R.M.
Total Score
RES
WEB
NET
FRA
TDI
8.1
5.5
0.9
2.0
1.5
32
21
15
14
12
FRA
BTG
NET
WEB
AWT
2.0
2.9
0.9
5.5
2.6
25
20
16
14
10
NET
BTG
FRA
WEB
RES
0.9
2.9
2.0
5.5
8.1
22
19
18
17
15
Scores for each time slice were calculated as the load within that time slice at a given site, minus
the load at the site immediately upriver. Total score is the sum of scores for each site across the
time slices sampled in sufficient number ( 6 sites sampled) during the storm. The site which
contributed the largest load within a time slice was assigned a score of 5; the site contributing the
second largest load was assigned a score of 4; and so on to the fifth largest load (score=1). The
maximum possible total score would be 40 (largest load in each of eight time slices).
2 Before calculating the score, the load difference between each pair of sites was divided by the
contributing area (ha) of the watershed that drained into the river between those two sites.
3 Calculated as above, except the loads were divided by the number of river miles between each pair
of sites.
Table 6.
Rank order bacteria load contributions at specific monitoring sites sampled 7 or more
times on the Trask River during all 12-hr time slices for which 6 or more sites were
sampled during the October 1997 storm. The top five load contributing sites are listed.
Ordered by Load'
Ordered by Load Per
Contributing Area 2
Ordered by Load Per River
Miles to Upriver Site3
Site
R.M.
Total Score
Site
R.M.
Total Score
Site
R.M.
Total Score
10L
ASF
TTR
HOQ
TEF
5TH
4.3
1.7
2.4
0.8
2.3
1.5
17
14
14
13
12
12
HOQ
5TH
0.8
1.5
2.4
3.2
3.6
2.7
19
19
19
13
12
12
TEF
5TH
2.3
1.5
2.4
3.6
0.8
23
17
14
13
12
TTR
DST
BTR
BPS
TTR
BTR
HOQ
1 Scores for each time slice were calculated as the load within that time slice at a given site, minus
the load at the site immediately upriver. Total score is the sum of scores for each site across the
time slices sampled in sufficient number ( 6 sites sampled) during the storm. The site which
contributed the largest load within a time slice was assigned a score of 5; the site contributing the
second largest load was assigned a score of 4; and so on to the fifth largest load (score = 1). The
maximum possible total score would be 40 (largest load in each of eight time slices).
2 Before calculating the score, the load difference between each pair of sites was divided by the
contributing area (ha) of the watershed that drained into the river between those two sites.
3 Calculated as above, except the loads were divided by the number of river miles between each pair
of sites.
May, 1998
Page 95
Results of Storm Sampling in the Tillamook Bay Watershed E&S Environmental Chemistry, Inc.
contributing areas were found as high upriver as the rest area (RM 8.1) and as low as RM 0.9
(Table 5). The major load-contributing sites on the Trask River were less well-distributed across the
basin, and tended to be clustered to some degree around the portions of the river that receive
drainage from the City of Tillamook and the site downriver from the Port of Tillamook STP discharge
point (10L, Table 6). The largest load-contributing site on the Trask River during both storms was
site 10L, which drains the area approximately between Chance Road and Highway 101. This same
section of the Trask River exhibited a rapid rise in FCB concentration in 1979 and 1980 (Jackson
and Glendening 1982).
The principal load-contributing sites during the March 1998 storm were generally similar to
those found for the October 1997 storm (Tables 5 and 7). However, the largest loads of FCB were
contributed during the March 1998 storm to the Tillamook River at site TIL-SFT, a site in the lower
reaches of the river with a very small watershed contributing area (Figure 3). Other major load
contributing sites were similar between the two storms on both the Tillamook and Trask Rivers
(Tables 5 through 8).
Thus, the overall trend for both the Tillamook and Trask Rivers during both the fall and spring
storms was as follows. FCB loads were low at all sites at the beginning and generally at the end
(depending on when sampling was discontinued) of the storms. At the uppermost sites, located in
the upper section of the agricultural portions of these watersheds, FCB loads remained low. At the
Table 7.
Rank order bacteria load contributions at monitoring sites on the Tillamook River during
all 12-hr time slices sampled during the March 1998 storm. The top five load
contributing sites are listed.
Ordered by Load'
Ordered by Load Per
Contributing Area l
Ordered by Load Per River
Miles to Upriver Site'
Site
R.M.
Total Score
Site
R.M.
Total Score
Site
R.M.
Total Score
SFT
RES
TDI
AWT
FRA
BTG
1.1
8.1
1.5
2.6
2.0
2.9
24
19
14
6
6
6
SFT
BTG
MID
TDI
AWT
FRA
1.1
2.9
4.5
1.5
2.6
2.0
25
15
14
10
8
8
SFT
BTG
TDI
AWT
BUR
ATG
1.1
2.9
1.5
2.6
4.0
3.1
30
13
10
7
7
7
1 Scores for each time slice were calculated as the load within that time slice at a given site, minus
the load at the site immediately upriver. Total score is the sum of scores for each site across the
time slices sampled in sufficient number ( 6 sites sampled) during the storm. The site which
contributed the largest load within a time slice was assigned a score of 5; the site contributing the
second largest load was assigned a score of 4; and so on to the fifth largest load (score = 1). The
maximum possible total score would be 35 (largest load in each of seven time slices).
2 Before calculating the score, the load difference between each pair of sites was divided by the
contributing area (ha) of the watershed that drained into the river between those two sites.
3 Calculated as above, except the loads were divided by the number of river miles between each pair
of sites.
Results of Storm Sampling in the Tillamook Bay Watershed
E&S Environmental Chemistry, Inc.
Table 8.
May, 1998
Page 96
Rank order bacteria load contributions at monitoring sites on the Trask River during all
12-hr time slices sampled during the March 1998 storm. The, top five load contributing
sites are listed.
Ordered by Load'
Ordered by Load Per
Contributing Area l
Ordered by Load Per River
Miles to Upriver Site3
Site
R.M.
Total Score
Site
R.M.
Total Score
Site
R.M.
Total Score
10L
5TH
4.3
1.5
2.3
1.7
1.2
3.7
16
15
14
14
10
10
TEF
5TH
2.3
22
17
14
13
8
5TH
1.5
0.8
2.7
1.7
1.2
21
TEF
ASF
HOB
ATR
ASF
HOB
ATR
1.5
1.7
1.2
3.7
HOQ
BPS
ASF
HOB
14
14
11
8
1 Scores for each time slice were calculated as the load within that time slice at a given site, minus
the load at the site immediately upriver. Total score is the sum of scores for each site across the
time slices sampled in sufficient number ( 6 sites sampled) during the storm. The site which
contributed the largest load within a time slice was assigned a score of 5; the site contributing the
second largest load was assigned a score of 4; and so on to the fifth largest load (score=1). The
maximum possible total score would be 35 (largest load in each of seven time slices).
2 Before calculating the score, the load difference between each pair of sites was divided by the
contributing area (ha) of the watershed that drained into the river between those two sites.
3 Calculated as above, except the loads were divided by the number of river miles between each pair
of sites.
uppermost Trask River site (Loren's Landing), this was mainly because FCB concentrations
remained low. At the uppermost Tillamook River site (Yellow Fir Rd.), this was because the
– discharge is low compared to the lower reaches of the Tillamook River (FCB concentrations were
frequently high). High loads were found at a variety of locations on both riyers. There was not one
major source area of FCB load on either river; the source areas were many and widely scattered.
The largest loads in both rivers were generally achieved in the lower two miles or so of river reach.
This suggests the cumulative effect of a large number of source areas within the agricultural
portions of the watersheds and/or a larger contribution of FCB close to the bay.
Jackson and Glendening (1982) found fairly uniform concentrations of fecal coliform bacteria
along the Tillamook River from the Yellow Fir Rd. bridge crossing down to the boat dock near the
last bridge crossing during two storms, in December 1979 and March 1980. Concentrations were
similar for the two storms, generally in the range of about 500 to about 1500 cfu/100 ml. The
sample site just above the rest area exhibited the highest concentrations during the July 1980
sampling and also the December 1979 and October 1980 storm samplings. Results of our analyses
confirm that this section of the Tillamook River remains one of the sections with highest FCB
loading.
Results of Storm Sampling in the Tillamook Bay Watershed E&S Environmental Chemistry, Inc.
May, 1998
Page 97
A site in the bay was monitored during the two intensive storm monitoring efforts. It was
adjacent to Memaloose Boat Launch, just north of where the Tillamook and Trask Rivers enter
Tillamook Bay. During high-discharge periods, a substantial amount of water flows past this point
from south to north. In some respects, this portion of the bay behaves more like a river than a bay
during significant storm events. The FCB concentration data for Memaloose Inlet are presented in
Figures 40 and 41. Wilson River discharge and precipitation at Tillamook are depicted in the lower
panel on each figure as a reference to hydrological conditions during the storm. During Storm 4,
FCB concentrations exceeded 1,000 cfu/100 ml on over half of the sampling occasions, with a peak
concentration of nearly 3,000 cfu/100 ml (Figure 40). These are extremely high concentrations
given that the bacterial standard for protecting the oyster beds located just north of this sampling
location is only 14 cfu/100 ml. Even during the spring storm (Storm 6), which resulted in much lower
FCB loads in the Tillamook and Trask Rivers, the FCB concentration at Memaloose Inlet was about
500 to 1,000 cfu/100 ml on half of the sampling occasions (Figure 41).
Jackson and Glendening (1982) also found quite high concentrations of fecal coliform bacteria
at locations throughout the bay in 1979 and 1980. Maximum values exceeding 900 cfu/ 100 ml
were found at 12 of 14 by sites during a 6 day storm event in December 1979. Highest
concentrations were found in the southern portion of the bay, especially near Rock Point along the
southwestern shore (median, 974 cfu/100 ml, n=9). Concentrations above 900 cfu/100 ml were also
measured in the bay at 4 sites during a 4-day storm in March, 1980. Again, highest concentrations
were found along the southwestern shore of the bay (median concentrations at Rock Point, 670
cfu/100 ml, n=9). Bay samplings in July and October 1980 yielded much lower concentrations,
although median concentrations in the southern (upper) portions of the bay were consistently higher
than 20 cfu/100 ml.
During a fall storm, October 24-26, 1980 (40 hrs), the fecal coliform load to the bay was
estimated to be highest in the Tillamook River, followed closely by the Wilson and Trask Rivers, with
somewhat smaller load contributions from the Miami, and especially the Kilchis River (Tillamook
SCD 1981). Our fall storm analyses in 1997, however, suggested much higher FCB loads in the
Trask, as compared with the Tillamook, River. Loading patterns were quite different in the other
seasons during 1979 and 1980. A winter storm, December 2-6, 1979 (91 hrs) yielded largest loads
in the Wilson and Trask Rivers, followed by the Kilchis, Tillamook, and finally Miami Rivers. During
a spring storm, March 10-13, 1980 (60 hrs), the Wilson, Trask, and Kilchis Rivers again had the
largest loads, followed by the Tillamook and finally the Miami Rivers (Tillamook SWCD 1981). Our
analyses suggested that FCB loads in the Kilchis River were nearly an order of magnitude lower
than FCB loads in the Tillamook River. Thus, there is some indication that the relative importance
of the various watersheds may have changed since 1980 regarding their contribution of FCB to the
bay.
Results of Storm Sampling in the Tillamook Bay Watershed
E&S Environmental Chemistry, Inc. May, 1998
Page 98
Memaloose Inlet
4.0
3.5
3.0
•
2.5
•
2.0
1.5
•
1.0
•
•
0.5
•
•
0.0 23SEP97
30SEP97
7OCT97
Wilson River Discharge at Sollie Smith Bridge
Figure 40. Concentration of fecal coliform bacteria measured at Memaloose Inlet, in the southern
portion of Tillamook Bay, during the October 1997 storm. Wilson River discharge and
precipitation at Tillamook are given in the lower panel for hydrologic reference.
Results of Storm Sampling in the Tillamook Bay Watershed
E&S Environmental Chemistry, Inc. May, 1998
Page 99
Memaloose Inlet
4.0
7
3.5
3.0
2.5
2.0
1.5
1.0
0.5
•
0.0 -
18FEB98
25FEB98
4MAR98
Wilson River Discharge at Sollie Smith Bridge
- 1.00
0.75
0.50
- 0.25
0.0 - 18FEB98
'
I
25FEB98
'
0.00
I
4MAR98
Figure 41. Concentration of fecal coliform bacteria measured at Memaloose Inlet, in the southern
portion of Tillamook Bay, during the March 1998 storm. Wilson River discharge and
precipitation at Tillamook are given in the lower panel for hydrologic reference.
Results of Storm Sampling in the Tillamook Bay Watershed
E&S Environmental Chemistry, Inc.
May, 1998
Page 100
Relationship Between FCB Loads and Land Use
Jackson and Glendening (1982) hypothesized that the primary sources of fecal coliform
bacteria to the rivers may require saturated ground. Source types that fit this pattern include field
application of manure, barnyards located some distance from the river, and inadequate on-site
sewage disposal systems. We evaluated the relationship between the segments of the Tillamook
and Trask Rivers that contributed the largest FCB loads and the land uses that were associated with
the lands that drained into those river segments. The objective was to look for land use patterns
associated with high FCB loading rates.
Evaluation of the spatial land use patterns within the contributing drainage areas to each of the
monitoring sites revealed some interesting patterns. The percentage of each drainage area within
agricultural, riparian, rural residential and urban land use categories is given in Table 9.
Percentages for a few of the sites on the Tillamook River were somewhat different between storms
because three new sites (TIL-AWT, TIL-TTR, and TIL-ATG) were added for the second intensivelymonitored storm. The frequency of farm building clusters and rural residential building clusters
within each drainage area are listed in Table 10.
During the October 1997 storm, the three sites on the Tillamook River that contributed the
largest FCB loads, compared to the neighboring upstream sites were TIL-RES, TIL-WEB, and TILNET. These were also the three sites with the highest frequencies of rural residential building
clusters (65, 70, and 27, respectively; Table 10). During this same storm, the three sites on the
Trask River that contributed the largest FCB loads were sites TRA-10L, TRA-ASF, and TRA-TTR.
Site TRA-10L also had the highest frequency of rural residential building clusters of the Trask River
sites (55; Table 10) and is the first site downriver of the discharge point from the Port of Tillamook
STP. Site TRA-ASF had only two rural residential building clusters (Table-10), but 66% of the
drainage area to this site was in urban land use (Table 9, third highest of the Trask River sites). Site
TRA-TTR had the second highest percentage of its contributing area in rural residential land use
(14%, Table 9).
Very similar results were found for the March 1998 storm. The three largest load contributors
on the Tillamook River were sites TIL-SFT, TIL-RES, and TIL-TDI (Table 7). Of these, only one
(TIL-RES) was high in rural residential building clusters (65), but the other two were within the top
four sites in terms of percentage of drainage subbasin in rural residential land use (4.3% and 5.0%,
Table 9). On the Trask River, the March 1998 storm yielded highest loads at sites TRA-10L, TRA5th , and TRA-TEF. These were second highest in terms of percent urban land use (TRA-5 th 88%)
and the highest (TRA-10L, 55) and third highest (TRA-TEF, 26) in terms of frequency of rural
residential building clusters (Table 10).
Results of Storm Sampling in the Tillamook Bay Watershed
E&S Environmental Chemistry, Inc.
May, 1998
Page 101
Table 9. Land use types by sample site subbasin in the Tillamook and Trask River watersheds.
Sub-basin
Area (ha)
%Rural
%Agricultural %Riparian Residential'
%Urban
%Forested Upland
and Other
Subbasins Sampled during the October 1997 Storm
TIL-BTG
109
80.0
1.1
TIL-FRA
133
56.5
3.5
TIL-BEW
529
46.3
4.4
TIL-ATG
90
40.9
0.0
TIL-SFT
15
39.5
0.1
TIL-TDI
632
36.9
0.4
TIL-RMO
272
30.6
0.7
TIL-NET
539
28.2
1.5
TIL-BUR
2079
25.3
4.4
TIL-AWT
148
21.5
2.9
TIL-RES
5058
10.0
1.5
TIL-WEB
2366
9.6
4.0
TIL-YEL
1063
7.3
0.0
TIL-FAW
1606
3.4
0.7
TIL-SIM
1095
2.0
0.3
3.0
0.6
6.2
3.0
4.3
5.0
0.1
4.4
0.7
1.1
2.8
2.1
0.7
2.5
0.5
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
18.9
40.0
49.4
59.1
60.4
62.7
68.7
70.2
70.3
75.5
88.5
86.4
92.7
95.8
97.7
Subbasins Sampled during the March 1998 Storm2
TIL-BTG
109
80.0
1.1
TIL-BUR
78
74.5
3.7
TIL-MIB
52
62.4
0.0
TIL-FRA
133
56.5
3.5
TIL-BEW
529
46.3
4.4
TIL-MID
622
45.3
10.6
TIL-SFT
15
39.5
0.1
TIL-TDI
632
36.9
0.4
TIL-RMO
272
30.6
0.7
TIL-NET
28.2
539
1.5
TIL-AWT
148
21.5
2.9
TIL-TTR
1379
13.4
1.7
TIL-ATG
38
10.9
0.0
TIL-RES
5058
1.5
10.0
TIL-WEB
9.6
4.0
2366
TIL-YEL
1063
7.3
0.0
TIL-FAW
1606
3.4
0.7
TIL-SIM
1095
2.0
0.3
3.0
1.4
5.2
0.6
6.2
1.6
4.3
5.0
0.1
4.4
1.1
0.3
0.0
2.8
2.1
0.7
2.5
0.5
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
18.9
21.8
37.6
40.0
49.4
44.1
60.4
62.7
68.7
70.2
75.5
84.9
89.1
88.5
86.4
92.7
95.8
97.7
Results of Storm Sampling in the Tillamook Bay Watershed
E&S Environmental Chemistry, Inc. Table 9.
Sub-basin
May, 1998
Page 102
Continued
Area (ha)
%Rural
%Agricultural %Riparian Residential'
%Urban
%Forested Upland
and Other
Subbasins Sampled in the Trask River during Both Storms2
5.0
TRA-ATR
0.0
64
93.7
1.4
7.0
10.4
TRA-DST
10.7
4
89.6
0.0
0.0
11.5
TRA-RMO
0.0
95
87.3
0.4
1.2
13.1
TRA-TTR
8.0
11
86.9
14.3
0.0
11.0
TRA-TEF
13.9
4.0
5.8
953
84.9
15.4
TRA-BTR
0.0
10
84.6
32.8
0.0
11.6
13.8
HOQ-CON
1160
83.8
3.6
4.5
16.5
0.0
TRA-BPS
19
80.8
2.8
4.8
32.9
2.6
TRA-HOQ
0.0
13
67.1
0.0
48.8
0.0
TRA-10L
10.9
1895
2.4
48.8
48.6
0.0
44.1
7.3
10.7
TRA-CHA
865
68.6
65.7
TRA-ASF
30.3
1.6
105
1.1
96.5
95.5
TRA-HOB
124
4.5
0.0
0.0
88.3
87.7
TRA-5TH
21
2.7
0.0
9.0
99.9
0.0
0.1
TRA-LOR
39673
0.1
0.0
1 Some areas were classified as both rural residential and as agricultural.
2 Three additional sites were added in the Tillamook watershed for the March 1998 storm that
were not sampled during the October 1997 storm.
These findings were unexpected and are very important. They provide very strong, albeit
circumstantial, evidence that the largest FCB loads within these two watersheds may in fact be
provided by human activities other than dairy farming. Urban areas appear to be significant
contributors, as do rural residential areas. The latter, however, may also contain intensive dairy
farming activities in some cases.
Sites on the Tillamook River that were important FCB load contributors, when expressed as per
unit area or per length of river were for the October 1997 storm:
TIL-NET
TIL-FRA
TIL-BTG
TIL-WEB
TIL-AWT, and
TIL-RES
Two were high in agricultural land use (TIL-BTG, and TIL-FRA); one was high in percent rural
residential land use (TIL-NET); and three were high in frequency of rural residential building clusters
TIL-WEB, TIL-RES, TIL-NET (These were actually the three highest sites in terms of rural
residential building clusters) (Table 10).
Results of Storm Sampling in the Tillamook Bay Watershed
E&S Environmental Chemistry, Inc. CD
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Results of Storm Sampling in the Tillamook Bay Watershed
E&S Environmental Chemistry, Inc.
May, 1998
Page 104
Many of these same sites had the largest FCB loads per unit area or per length of river during
the March 1998 storm. A couple of additional sites also emerged as important during the March
intensive storm:
TIL-SFT
TIL-MID
TIL-TDI
TIL-BUR, and
TIL-ATG
Site TIL-SFT was unusual in that it so clearly dominated the FCB loading per unit area and per river
length during this storm. It was relatively high in percent agricultural land use (40%). In fact, four of
these five sites were high in percent agricultural land use (37% to 75%, Table 9).
On the Trask River, the sites that contributed the largest FCB loads per unit area and per river
length were during the October 1997 storm:
TRA-5th
TRA-TEF
TRA-HOQ
TRA-ASF
TRA-BPS
TRA-HOB, and
TRA-ATR
Four of these sites (TRA-HOB, TRA-5 th , TRA-ASF, and TRA-TEF) were the four highest in the
watershed in terms of percent urban land use. Three of the other four had percent agricultural land
use greater than 67% (Table 9). During the March 1998 storm, the same Trask River sites were
highest in FCB load per unit area and per river length as was found during the October storm.
These same land use analyses were repeated for a set of drainage areas (subbasins) defined
in a different way. For this second set of land use analyses, the drainage areas contributing to each
sampling site were restricted to those within 100m on either side of waterways (river, tributary
streams and/or drainage ditches). These buffer zones are shown in Figures 42 and 43 for the
Tillamook and Trask Rivers, respectively. The percentages of the area within the various land use
types that occurred in the buffered streamside portion of the sample site drainage area subbasins
are listed in Table 11. The numbers of farm building and rural residential building clusters within
each of the buffered subbasins are listed in Table 12
On the Tillamook River, during the October storm, the three highest load-contributing sites
(RES, WEB, and NET) were also the three highest sites in number of rural residential building
clusters within the buffered streamside areas (Table 12). Four of the top five load-contributing sites
were also four of the top five sites in number of farm building clusters within the streamside buffer
zones (NET, WEB, RES, TDI). During the March storm, only the RES site was high in both FCB
loads (Table 7) and number of rural residential building clusters (Table 12). Half of the top six load-
Results of Storm Sampling in the Tillamook Bay Watershed
E&S Environmental Chemistry, Inc. May, 1998
Page 105
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Results of Storm Sampling in the Tillamook Bay Watershed E&S Environmental Chemistry, Inc.
May, 1998
Page 106
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Page 107
Results of Storm Sampling in the Tillamook Bay Watershed
E&S Environmental Chemistry, Inc.
Table 11. Land use types by sample site subbasin within a 100 m buffer zone on either side of the river
plus all tributary streams and drainage ditches.
Sub-basin
Area (ha)
%Agricultural
%Riparian
%Rural
Residential
%Forested Upland
and Other
%Urban
Subbasins Sampled during the October 1997 Storm
TIL-BTG
63
84.4
1.9
TIL-TDI
229
81.6
1.1
93
TIL-FRA
79.9
5.1
TIL-ATG
47
67.8
0.0
TIL-BEW
197
65.6
8.6
TIL-NET
202
60.0
3.4
TIL-SFT
10
55.2
0.1
TIL-RMO
137
55.0
1.3
TIL-BUR
573
53.7
13.0
TIL-AWT
69
46.1
6.3
TIL-YEL
155
33.2
0.0
TIL-RES
1192
23.1
4.4
TIL-WEB
531
21.5
15.7
TIL-FAW
409
9.8
2.5
TIL-SIM
199
1.7
5.0
1.8
1.4
0.9
0.0
9.7
7.5
1.1
0.1
0.9
2.3
0.8
4.6
4.4
4.9
2.8
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
13.7
17.3
15.0
32.2
25.8
36.6
44.7
43.7
33.3
47.5
66.8
72.5
62.7
87.7
93.3
Subbasins Sampled during the March 1998 Storm
TIL-BTG
63
84.4
1.9
TIL-MIB
33
83.7
0.0
TIL-BUR
7.7
36
82.5
TIL-TDI
229
81.6
1.1
TIL-FRA
93
79.9
5.1
197
TIL-BEW
65.6
8.6
TIL-MID
230
63.0
23.6
TIL-NET
202
60.0
3.4
TIL-SFT
10
55.2
0.1
TIL-RMO
137
55.0
1.3
TIL-AWT
69
46.1
6.3
TIL-TTR
5.7
308
43.4
TIL-YEL
155
33.2
0.0
TIL-ATG
14
29.7
0.0
1192
TIL-RES
23.1
4.4
15.7
TIL-WEB
531
21.5
TIL-FAW
409
9.8
2.5
TIL-SIM
199
5.0
1.7
1.8
0.0
0.6
1.4
0.9
9.7
1.0
7.5
1.1
0.1
2.3
0.8
0.8
0.0
4.6
4.4
4.9
2.8
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
13.7
16.3
9.8
17.3
15.0
25.8
13.5
36.6
44.7
43.7
47.5
50.8
66.8
70.3
72.5
62.7
87.7
93.3
Results of Storm Sampling in the Tillamook Bay Watershed
E&S Environmental Chemistry, Inc. May, 1998
Page 108
Table 11. Continued
Sub-basin
Area (ha)
%Agricultural
%Riparian
%Rural1
i
Residential
%Urban
Subbasins Sampled in the Trask River during Both Storms
TRA-RMO
0.4
1.2
92
86.9
0.0
TRA-TEF
4.8
404
84.2
6.6
12.4
TRA-DST
0.0
3
84.1
0.0
16.4
7.2
TRA-ATR
82.5
23
3.8
0.0
TRA-BTR
26.1
81.2
8
0.0
0.0
4.4
TRA-TTR
7
77.4
14.0
0.0
77.2
TRA-BPS
16
3.3
0.0
5.7
0.7
76.7
10.4
HOQ-CON
385
9.0
0.0
67.2
TRA-HOQ
13
2.6
0.0
TRA-10L
13.3
51.6
0.0
678
5.4
1.9
TRA-ASF
49.2
5.0
20
30.2
4.8
TRA-CHA
47.0
292
10.5
0.0
0.0
TRA-HOB
5
38.7
41.1
0.0
0.0
TRA-5TH
9
6.3
71.9
14.3
0.3
0.2
TRA-LOR
5740
0.1
0.0
'Some areas were classified as both rural residential and as agricultural.
%Forested
Upland and Other
11.9
9.1
15.9
13.8
18.8
22.6
19.5
14.3
32.8
43.0
45.8
42.5
61.3
79.4
99.7
contributing sites (TDI, FRA, BTG) were also high (>80%) in percent of buffer zone in agricultural
use (Table 11).
On the Trask River, during the October storm, the six highest load contributing sites (Table 6)
included four of the six buffered drainage areas having highest percentage of rural residential lands
plus the site having the second highest percentage of urban land. During'the March 1998 storm, the
six highest FCB load contributing sites included the three sites having the highest percentage of
their buffered drainage area in rural residential land use plus three of the five sites having the
highest percentage of their buffered drainage area in urban land use (Table 11). Also, two of the top
three load-contributing sites contained two of the three highest numbers of rural residential building
clusters (Table 12). Two sites (10L and TEF) contained large numbers of both farm building
clusters and rural residential building clusters.
The results of our analyses suggest that the largest FCB loads were contributed by urban and
rural residential land use activities especially during the fall storm, when loads were very high.
These high loads were particularly evident in the lower reaches of the Trask River. The high load
contribution from the lower sections of the Trask River can easily be seen by comparing results
obtained at the primary Trask River site (Tillamook Toll Rd.) with results obtained at the 5 th St. dock
during the two storms that were sampled at both sites. Although these two sites are only 0.9 mi.
Results of Storm Sampling in the Tillamook Bay Watershed
E&S Environmental Chemistry, Inc.
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Results of Storm Sampling in the Tillamook Bay Watershed
E&S Environmental Chemistry, Inc. May, 1998
Page 110
Table 13. Comparison of results obtained for fecal coliform bacteria concentrations and loads
between the primary site on the Trask River (Tillamook Toll Rd. Bridge, TTR) and the
5th St. dock, which is 0.9 miles downriver from TTR, during the two intensively-sampled
storms.
Site Comparison for 5th Street Dock and TTR
Storm
Dates
Water
Volume (m3 x
106)
Peak River
Discharge
(cfs x 103)
Peak FCB
(cfu/100 ml)
Total FCB
Load
(cfu x 1012)
56'
TTR
561
TTR
561
TTR
5'hTTR
4
9/30/97 - 10/8/97
5.9
5.8
2300
2800
37.9
37.2
330
225
6
2/27/98 - 03/8/98
3.3
3.3
880
440
50.4
49.6
190
34
apart, the peak FCB loads achieved and the cumulative storm loads were quite different between
the sites (Table 13). For example, the total storm FCB load at the downriver site (5 th St. dock) was
almost 50% higher during the October storm and over 400% higher during the March storm as
compared with the upriver site. Relatively large loads were also associated with high percentage of
drainage contributing area in agricultual land use, especially when load estimates were expressed
on a per unit area or per river length basis and when land use was evaluated within streamside
buffer zones. Agricultural contributions appeared to be proportionately higher during the March
storm than during the October storm.
Earlier research by Jackson and Glendening (1982) also concluded that most of the fecal
contamination in the Tillamook River subbasin occurred below the forest/agriculture boundary in the
area that contains homes and dairy farms. They were unable to make definitive statements
regarding the extent of the contribution that might have been coming from homes having inadequate
on-site subsurface sewage disposal systems. However, based on a comparative analysis of the
Munson Creek and Bewley Creek subbasins, Jackson and Glendening (1982) hypothesized that the
most likely source was farms with barnyards near the creeks. The results of our analyses do not
dispute Jackson and Glendening's hypothesis that dairy farms and associated barnyards are
important sources of FCB contamination of drainage waters in the Tillamook River watershed.
However, the results of our analyses suggest that FCB sources associated with human activities
other than dairy farming (e.g., urban land use in the Trask River watershed and rural residential
dwellings in both the Tillamook and Trask River watersheds) are likely more important FCB sources.
Results of Storm Sampling in the Tillamook Bay Watershed
E&S Environmental Chemistry, Inc.
May, 1998
Page 111
CONCLUSIONS
A number of conclusions can be drawn from the storm sampling that was conducted in the
rivers of the Tillamook Bay watershed. Key conclusions include the following:
• The largest loads of FCB to Tillamook Bay are contributed by the Trask River, followed by
the Wilson and then the Tillamook River. FCB loads in the Miami and Kilchis Rivers are
lower than the other three rivers by about an order of magnitude.
• The largest loads of nitrogen to Tillamook Bay are contributed by the Trask River,
followed by the Wilson River.
• The largest loads of TSS and TP (which are likely both primarily from erosional
materials) are contributed by the Wilson River, followed by the Trask River.
• FCB loads in a given river differed markedly from storm to storm, with highest loads (by a
substantial margin) contributed by the early fall storm.
• The highest concentrations of FCB were generally achieved well before the time of peak
river discharge, and generally occurred during the period of most intensive rainfall.
• The largest FCB storm loads were reached in the mid-section of the Tillamook River and
in the lower sections of both the Tillamook and Trask Rivers. However, FCB contributions
were substantial throughout both watersheds.
• The land areas that contributed the largest FCB loads to the Trask River were those
containing urban land use. Other land uses associated with areas that contributed large
FCB loads were rural residential and agricultural land use. The land uses that contributed
the largest FCB loads to the Tillamook River (whose watershed does not include urban
land use) were rural residential and'agricultural land uses.
These results suggest that the largest contributions of FCB to the Tillamook and Trask Rivers,
at least during the two storms that were intensively monitored, occurred in associated with human
habitation, especially the urban areas of the Trask River watershed and the rural residential areas of
the Tillamook River watershed. Agricultural land use was also an important FCB contributor in the
Tillamook River watershed. Highest loads were generally found in the lower sections of the rivers,
which are heavily ditched and where human activity is concentrated, soils are poorly drained, and
runoff potential is high.
Results of Storm Sampling in the Tillamook Bay Watershed
E&S Environmental Chemistry, Inc. May, 1998-- -Page 112
REFERENCES
USDA-SCS. 1978. Tillamook Bay Drainage Basin Erosion and Sediment Study, Portland, OR.
Bernert, J.A. and T. J. Sullivan. 1997. Quality Assurance Plan for the Tillamook Bay National
Estuary Project, River Water Quality Monitoring Project, E&S Environmental Chemistry, Inc.,
Corvallis, OR. Report Number 96-20-01.
Bernert, J.A. and T.J. Sullivan. 1998. Bathymetric Analysis of Tillamook Bay, E&S Environmental
Chemistry, Inc., Corvallis, OR.
Greenberg, A.E.,
Clesceri, and A.D. Eaton, Eds. 1992. Standard Methods for the Examination
of Water and Wastewater. 18th ed. American Public Health Assoc./American Water Works
Assoc./Water Environment Federation, Washington, DC.
Jackson, J. and E. Glendening. 1982. Tillamook Bay bacteria study fecal source summary report.
Oregon Department of Environmental Quality, Portland, OR.
Sullivan, T.J., J.M. Bischoff, K.B. Vache, M. Wustenberg, J. Moore. In review. Water Quality
Monitoring in the Tillamook Watershed, Final Report to the Tillamook Bay National Estuary Project,
E&S Environmental Chemistry, Inc., Corvallis, OR.
Tillamook County SWCD and Tillamook Bay Water Quality Committee. 1981. Tillamook Bay
Drainage Basin Agricultural Non-point Source Pollution Abatement Plan, Tillamook, OR.