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

gbowen@trca.on.ca