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Annual and seasonal differences
in nearshore water quality of
Lake Ontario by Western
Durham in relation to wet and
dry years
Krista Chomicki
Carolyn Brown
Gary Bowen
Acknowledgements
• Environment Canada
• Ontario Ministry of the Environment
• Regional Municipalities of York and Durham
• Toronto and Region Conservation Authority
field team
• Maryam Nassar
• 2006 preliminary
investigations
• Rotary Park:
– no longer sampled
by the Health
Department
– not physically safe
to swim due to
shoreline protection
– Barrier beach with
wildlife from
river/creek area
– Provincially
significant marsh
The Western Durham Monitoring Program
Rotary
Park
Paradise
Park
Drinking water
Intake Duffin Pollution
Control Plant
Outfall
TRCA AQUALAB
• 2 boats required
• Predominantly surface
water samples,
however samples were
taken at depth along
the WWTP outfall
transect
• Preliminary data (2006-
2007) was made
available to the MOE,
who monitored the
area in 2008
• Part of the International
Year of Study for Lake
Ontario
Sampling Locations 2007 - 2010
Drinking
water
Intake
Duffin Creek
Pollution
Control Plant
Outfall
The Western Durham Monitoring Program
• One of the most
comprehensive
nearshore water
sampling collection
efforts in the Great
Lakes;
• In total, there are:
~45 SURVEYS
• Water quality under
a variety of lake
conditions
• Survey design is for
regional look at
water quality, not to
track plumes
Design Re-evaluated: 2011 to 2013
Drinking water
Intake
Duffin Creek
Pollution
Control Plant
Outfall
LOBO
The Western Durham Monitoring Program
OPG
Monthly Lake Ontario water level
Date
Wate
r Level (m
)
0.0
0.2
0.4
0.6
0.8
1.0
1.2
Lake Ontario Lake Levels
DRY
2007
AVG
2010
DRY
2012
WET
2008
WET
2009
WET
2011
WET
2006
2006 2007 2008 2008 2010 2011 2012
Record low
to
Record high
Precipitation • Wet and Dry years defined in comparison to the 30 year average
30 y
ear
avera
ge
2007
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan
Dis
charg
e (
m3/s
)
0
20
40
60
Conductivity (
S/c
m)
295
300
305
310
315
320
Pre
cip
itation (
mm
)
0
20
40
60
80
100
Discharge (TRCA)
Conductivity (MOE) - No ADCP
Precipitation (TRCA)
2008
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan
Dis
charg
e (
m3/s
)
0
20
40
60
Conductivity (
S/c
m)
295
300
305
310
315
320
Pre
cip
itation (
mm
)
0
20
40
60
80
100
Discharge (TRCA)
Conductivity (MOE)
Precipitation (TRCA)
2009
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan
Dis
charg
e (
m3/s
)
0
20
40
60
Conductivity (
S/c
m)
295
300
305
310
315
320
Pre
cip
itation (
mm
)
0
20
40
60
80
100
Discharge (TRCA)
Conductivity (MOE)
Precipitation (TRCA)
2010
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan
Dis
charg
e (
m3/s
)
0
20
40
60
Conductivity (
S/c
m)
295
300
305
310
315
320
Pre
cip
itation (
mm
)
0
20
40
60
80
100
Discharge (TRCA)
Conductivity (MOE)
Precipitation (TRCA)
2011
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan
Dis
charg
e (
m3/s
)
0
20
40
60
Conductivity (
S/c
m)
300
310
320
330
340
Pre
cip
itation (
mm
)
0
20
40
60
80
100
Discharge (TRCA)
Conductivity (MOE)
Precipitation (TRCA)
2012
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan
Dis
charg
e (
m3/s
)
0
20
40
60
Conductivity (
S/c
m)
295
300
305
310
315
320
Pre
cip
itation (
mm
)
0
20
40
60
80
100
Discharge (TRCA)
Conductivity (MOE)
Precipitation (TRCA)
DRY
2007
AVG
2010
DRY
2012
WET
2008
WET
2009
WET
2011
Percent of TRCA samples that are
NON-DETECTS
Year Alk Cond E Coli NH3 NO3+NO2 NO2 TP pH SRP TKN SS
2007 39 28 74 42 78 56
2008 NO NO 17 30 NO 8 NO 73 NO 55
2009 NDs NDs 26 NDs 1 10 NDs 60 NDs 33
2011 NS 24 50 90 62
2012 NS 18 8 34 97 77
min 17 18 1 8 60 33
max 39 30 74 50 97 77
NO NDs = No NON-DETECTS, nor are they expected
Range in TP (mg/L) for ALL data Range in TP (mg/L) for Overlapping sites
D W W A W D • 2010
– Only sampled once
• 2011
– No spring sampling
Tota
l P
hosphoru
s (m
g/L
)
D W W A W D
IJC open water objective
Maximum detection limit = 6mg/L
Range in TP (mg/L)
D W W A W D
D
IJC open water objective
Maximum detection limit = 6 mg/L
Range in SRP (mg/L)
Maximum detection limit = 4 mg/L
MAJORITY OF SAMPLES
ARE BELOW DETECTION
2008 TO 2012: NO
DIFFERENCE
Range in TKN (mg/L)
Range in NO3 (mg/L)
Range in SS (mg/L) for Overlapping
sites
2008 and 2009: NO DIFFERENCE
2007 and 2012: NO DIFFERENCE
2012 from 2008: NO DIFFERENCE 2012 from 2009: DIFFERENCE
NO DIFFERENCE or
DIFFERENCE and
D W W A W D
Seasonal
Water
Quality • Total Phosphorus
(mg/L)
• Generally, greater variability in spring and fall...summer range due to 1-2 points
• Summer and fall median concentrations appear to be lower in dry years
2007 (D) 2008 (W) 2009 (W)
2010 (A) 2012 (D) 2011 (W)
Does the data show Seasonality?
Soluble
Reactive
Phosphorus • µg/L
• More variation
observed in
spring and fall
• Almost all
samples are
below detection
• 2007 summer
2010, 2011
summer: all
below detection
2007 (D) 2008 (W) 2009 (W)
2010 (A) 2012 (D) 2011 (W)
No
samples
All
Non-detects
2 detected
Samples
4-100
4-1000
1 detected
sample
1-100
Nitrate +
Nitrite
• µg/L
• Highest
concentrations
observed in spring
and fall
• Median
concentrations
appear to be
higher in wet
years
2007 (D) 2008 (W) 2009 (W)
2010 (A) 2012 (D) 2011 (W)
Suspended
Solids • mg/L
• No observed
trend in
variability
• Not unexpected
-possibly
related to
timing of large
discharge and
precipitation
events, or large
mixing events
in the lake
2007 (D) 2008 (W) 2009 (W)
2010 (A) 2012 (D) 2011 (W)
No
samples
Seasonal
• Seasonal variability
– Between seasons: greater variability in spring and fall
– Summer and fall median TP concentrations appear to be lower in dry years
– Summer and fall Nitrate median concentrations appear to be higher in wet years
• TP: Wet ≠ Dry
• SRP: no significant difference
• NO3: Wet ≠ Dry (summer and fall)
– Spring is the same across all years
• SS: all over the board with significance – timing of events?
Redundancy Analysis
Controlling independent variables:
Environmental variables
Response dependent variables:
Water quality
Seasonal importance? Spring
Summer
Fall
Seasonal importance?
Discharge
0 2 4 6 8 10 12 14
Tota
l P
hosphoru
s
0
5
10
15
20
25
30
35
40
Spring
Summer
Fall
Discharge
0 2 4 6 8 10 12 14
TK
N
200
250
300
350
400
450
Spring
Summer
Fall
Why isn’t the variability explained?
Relationship between discharge and
concentration doesn’t depend on season
In terms of significance, 2011 is often more similar to 2007 and 2012
Despite being a “wet” year, half of precipitation and majority of discharge came outside of the
sampling season
Next steps:
-relate to seasonal water quality
Varies by year
What’s next?
• l
Effort to get a handle on P forms
-lower level P detection
Pursuing collaborative research
Better understand processes
Lake level changes?
The data (2007-2013) is online:
• http://theskua.com/wqapp/
For more information:
• http://www.trca.on.ca/the-living-city/watersheds/lake-ontario-
waterfront/western-durham-waterfront-monitoring.dot
Take Home Messages
• SEASONAL
– Higher nutrient concentrations are observed in spring and fall
• TEMPORAL
– It appears that concentrations are lower in “dry” years than in “wet”
years
• Although physical and environmental characteristics explain 78% of the
water quality variability, they only explain 44% of the seasonality
• Next steps: attempting to relate seasonal work to timing and size of
precipitation and discharge events
• Monitoring is to continue until 2016 - for more information contact