Figure II. 1. The percentage of total dissolved nitrogen composed of nitrate, and the percentage of total dissolved
phosphorous consisting of phosphate, at sites in the Ventura River watershed. Shown are averages (+ 2SE) for all data
collected from 2001-2008 (nitrogen) or 2005-2008 (phosphorous), as well as for the dry seasons (May-Sept.) for those
years.
NO3 as a % of TDN
100%
all data
May-Sept.
80%
60%
40%
20%
C
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M
ai
D
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0%
100%
May-Sept.
80%
60%
40%
20%
U
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0%
M
ai
PO4 as a % of TDP
all data
Figure II.2. Hydrograph (flow rate over time) for the Ventura River at Foster Park (VR06) and for effluent from the OVSD
treatment plant (WWTP) from October 2000 to October 2008.
Figure II.3. Changes in nutrient concentrations (total dissolved phosphorous (TDP), soluble reactive phosphorous (PO4),
total dissolved nitrogen (TDN), and nitrate (NO3)) and total suspended solids in the Ventura River at Main Street over
weak (February 2003, left) and large (March 2003, right) storm events. The storm hydrograph for the Ventura River at
Foster Park is also shown as a continuous grey line and the vertical red line indicates the time of minimum conductivity
at Main Street, i.e. the time of probable peak Main Street discharge.
0.3
15
0.4
10,000
TDP
10
0.1
5
TDP
PO4
26-Feb
27-Feb
28-Feb
0.2
100
0.1
10
0.0
0
25-Feb
1,000
flow
0.0
24-Feb
flow
flow (cfs)
phosphorus (mg/L)
0.2
flow (cfs)
phosphorus (mg/L)
PO4
0.3
1-Mar
3
15
2
10
1
15-Mar
2-Mar
16-Mar
17-Mar
18-Mar
3
10,000
1
5
100
flow (cfs)
nitrogen (mg/L)
flow (cfs)
nitrogen (mg/L)
1,000
2
1
TDN
10
NO3
NO3
flow
25-Feb
26-Feb
27-Feb
28-Feb
1-Mar
10
500
5
TSS
flow
0
0
25-Feb
26-Feb
27-Feb
28-Feb
1-Mar
2-Mar
16-Mar
17-Mar
18-Mar
30,000
15
1,000
24-Feb
2-Mar
total suspended solids (mg/L)
1,500
1
15-Mar
flow (cfs)
24-Feb
total suspended solids (mg/L)
flow
0
0
10,000
TSS
flow
1,000
20,000
100
10,000
10
0
15-Mar
1
16-Mar
17-Mar
18-Mar
flow (cfs)
TDN
0
Figure II.4. Concentration-discharge curves for the Ventura River at Main Street during the March 2003 storm. Nutrient
(PO4, NO3) and suspended solids concentrations, and conductivity, are plotted against river discharge, and numbers next
to data points represent hours since the beginning of sampling. Note that suspended solids values proceed through
time in a clock-wise direction, whereas nutrient concentrations and conductivity proceed through time in a counterclockwise direction.
TSS
12
PO4
0.2
8
pre-storm
5
10,000
12
20
2
32
0.1
8
20
1,000
0
phosphate (mg/L)
total suspended solids (mg/L)
100,000
5
2
0
32
100
0.0
1
10
100
1,000
10,000
flow in cfs (Foster Park)
TSS
2.0
NO3
32
8
pre-storm
5
10,000
2
12
20
5
2
1,000
12
1.0
8
0
nitrate (mg/L)
total suspended solids (mg/L)
100,000
20
0
32
100
0.0
1
10
100
1,000
10,000
flow in cfs (Foster Park)
2000
2.0
spec. cond.
nitrate (mg/L)
1500
512
173
32
24
1000
106
1.0
17
2
1
7
14
20
3
8
0
4
5
9
12
500
10
0.0
0
1
10
100
1,000
flow in cfs (Foster Park)
10,000
conductivity (µS/cm)
NO3
pre-storm
Figure II.5. Nitrate concentrations and discharge (grey lines) at designated sites in the Ventura River basin, 2001-2008 The dashed line indicates the TN level
proposed to demarcate high from medium quality waters and the red solid liine demarcates the TN level proposed to delineate medium from poor quality
waters.
Figure II.6. Relationships between nitrate and phosphate concentrations at sites in the lower Ventura River and the % of total discharge contributed by the OVSD
plant. The tight relationship between nitrate or phosphate concentrations and OVSD contributions apparent at sites below the OVSD plant (e.g., Shell Road) is
lowered and disappears at the lowest Ventura River site (Main Street), because of uptake and removal from the water column by plants, algae, and bacteria in
the lower river. Regression equations and associated R2’s for relationships are shown.
Figure II.7. Long-term changes in nitrate concentrations and conductivity at the site on upper San Antonio Creek.
Nitrate and conductivity reached a minimum during the largest storms (2001, 2005), then showed multi-year trends
between these events. Dashed lines were visually added to show trends.
Figure II. 8. Total dissolved nitrogen concentrations and discharge (grey line) at designated sites in the Ventura River basin, 2000 – 2008. Dashed line demarcates proposed TN
levels for high vs. medium quality waters and solid red line demarcates proposed TN levels demarcating medium and poor quality waters.
Figure II.9. Phosphate concentrations and discharge (grey line) at designated sites in the Ventura River basin, 2000 – 2008. The dashed blue line demarcates
proposed TP levels demarcating high and medium quality waters, whereas the solid red line demarcates proposed TP levels demarcating medium and high water
quality levels.
Figure II.10. Total dissolved phosphorous concentrations and discharge (grey line) at designated sites in the Ventura River basin, 2000 – 2008. Solid red and dashed blue lines as
in previous figures.
Figure II.11. Nitrate (blue diamonds) and total dissolved nitrogen concentrations (red circles) in the Ventura River at Shell Road and Foster Park,
lower San Antonio Creek, and the North Fork Matilija Creek from 2001-2008. Solid red and dashed blue lines demarcate proposed low to medium
and medium to high water quality boundaries.
Lower San Antonio Creek
North Fork Matilija Creek
Figure II.12. Phosphate (blue diamonds) and total dissolved phosphorous concentrations (red circles) in the Ventura River at Shell Road and Foster
Park, lower San Antonio Creek, and the North Fork of Matilija Creek from 2001-2008. Horizontal lines as in previous figures.
Foster Park
Figure II.13. Diel (24-hour) changes in nitrate (blue circles) and phosphate (red squares) concentrations in the Ventura River at Foster Park (VR-06)
on September 10-11, 2003. On these dates, sunset was at 1810 hs and sunrise was at 0638 hs.
NO3
PO4
Figure II.14. Comparisons of average monthly nitrate concentrations from 20001-2007 (+ 2 SE) with monthly nitrate concentrations in 2008 at designated sites in
the Ventura River. Patterns for total dissolved nitrogen were similar.
Fig. II. 15. Comparisons of overall and yearly average dry season nitrate concentrations from 2001-2007 (±2 SE) with nitrate concentrations from 2008 across
designated sites in the Ventura River basin. Solid red and dashed blue lines demarcate proposed TN levels for poor-medium and medium-high quality waters,
respectively.
Figure II.16. Comparisons of overall (± 2 SE) and yearly average total dissolved nitrogen concentrations for the entire year and dry season from 2001-2007 with
total dissolved nitrogen concentrations from 2008 across designated sites in the Ventura River basin. Horizontal lines as in previous figure.
Fig. II. 17. Comparison of average monthly phosphate concentrations from 2005 – 2007 (± 2 SE) with monthly phosphate concentrations from 2008 at
designated sites in the Ventura River basin. Patterns for total dissolved phosphorous were similar.
Fig. II.18. Comparisons of overall, dry season (May through Sept), and annual average phosphate concentrations (± 2 SE) from 2005 to 2007 with phosphate
concentrations recorded in 2008 across designated sites in the Ventura River basin. Horizontal lines as in Fig. II.16.
Fig. II.19. Comparisons of overall, dry season (May through Sept), and annual average total dissolved phosphorous concentrations from 2005 to 2007 with total
dissolved phosphorous concentrations recorded in 2008 across designated sites in the Ventura River basin. Horizontal lines as in Fig. II.16.
Figure II. 20. Scatter plot of monthly total dissolved phosphorous and total dissolved nitrogen concentrations for designated sites in the Ventura
River basin from Jan. 2005 to Sept. 2008. The solid lines within the graph represents upper levels for TP and TN, beyond which water quality is
rated poor, whereas the dashed line indicates TP and TN levels below which water quality is rated high. Areas in between the solid and dashed
lines represents sites and times with medium water quality.
Fig. II. 21. Daily nitrate flux at designated sites in the Ventura River basin. Flux was calculated as nutrient concentration times average daily flow volume.
Fig II.22. Daily phosphate flux at designated sites or combinations of sites in the Ventura River Basin, 2001 – 2008. Calculations as in Fig. II.21.
Figure II. 23. Diel (24-hour) changes in river pH, dissolved oxygen, and temperature at sites in the Ventura River watershed. Light
blue (April 9, May 15, June 17, and July 25, from left to right for each site) and dark blue (Sept. 12) bars represent pre-dawn levels
whereas the tops of tan (4/09, 5/15, 6/17, 7/25) and gray (9/12) bars represent afternoon levels, at designated sites within the
Ventura River basin.
Pre-dawn =
and
[
T
y
p
e
(9/12); Afternoon =
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y
p
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u
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t
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t
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s
u
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r
s
u
m
m
a
r
and
(9/12)
Fig. II. 24. (Top) Relationship between dissolved oxygen concentration measured just before dawn and algal
biomass (as chlorophyll a concentration) across sites in the Ventura River basin in June and September,
2008. Note the log-scale of axes. The regression equation and associated coefficient of determination (R2)
and P values are presented.
(Bottom) Relationship between predicted and measured concentrations of dissolved oxygen just before dawn
across monitoring sites in the Ventura River basin. Predicted values were obtained from a best fit regression
equation where minimum (pre-dawn) oxygen concentration was the dependent variable and algal biomass (as
chlorophyll a concentration) and flow rate (in cfs) were the independent variables. The multiple regression
equation and R2 and P values for the predicted vs. observed DO level regression are shown.
Appendix. II. Figure 1: Comparisons of nutrient results from various data sources. Small symbols (blue or green cicles or triangles) are data from Channel
Keeper (CBCK) for sites on the Ventura River at Foster Park and Shell Road, whereas data from other sources, such as the Ojai Valley Sanitation District or the
UCSB SBC LTER program are shown with red symbols or large blue circles or violet triangles. OVSD data are from waste water treatment plant effuent (WWTP),
above and below (outfall) the WWTP, the Ventura River’s confluence with Canada Larga, and the Ventura River at Shell Road and above the confluence with
San Antonio Creek. LTER data were taken from the lower Ventura Rive and Foster Park.
Appendix II. Figure 2. Comparisons of nutrient results from different laboratories (UCSB’s Marine Science Institute , UCSB’s SBC LTER program, and UC Davis’s
Analytical Lab), as well as comparisons of samples filtered (f) through GFF filters (0.45 mm pore size) and samples that were unfiltered (u). Comparisons are for
the same Ventura River sites sampled at the same times.