2004 Shoal Lake water quality test results

Our staff test Shoal Lake and the intake at the west end of Indian Bay (where the water enters the aqueduct) as part of our routine water quality testing program.

For more information on Winnipeg's drinking water and our impact on Shoal Lake, visit the web page on Shoal Lake - Our Water Source.

Testing

We take samples at the intake every week during the open water season and every two weeks during the rest of the year. We also take samples from the Shoal Lake watershed from May to October. We test the intake samples for:

• routine water chemistry
• taste and odour compounds
• metals
• disinfection by-products
• bacteria and protozoa
• toxins produced by algae

By taking these samples, we track seasonal changes in water quality and determine the effects (if any) of human activity within the Shoal Lake watershed.

The intake for the aqueduct is at the west end of Indian Bay. Water entering the intake passes through screens before being disinfected by chlorine. We add sufficient chlorine to maintain a free chlorine residual of about 0.3 milligrams per litre in the water in the aqueduct when it enters Deacon Reservoir.

What is being measured	How it's measured	Guideline or regulation	Shoal Lake average	Shoal Lake range	Comments
Odour	odour number	inoffensive	100	40 to more than 200	Raw water - guideline does not apply
Geosmin	parts per trillion	no guideline	5	<1 to 18	Common taste and odour compound
IPMP - 2-isopropyl-3-methoxypyrazine	parts per trillion	no guideline	<2	<2	Common taste and odour compound
IBMP - 2-isobutyl-3-methoxypyrazine	parts per trillion	no guideline	<2	<2	Common taste and odour compound
MIB - 2-methylisoborneol	parts per trillion	no guideline	<10	<2 to <10	Common taste and odour compound
246 TCA - 2,4,6-trichloroanisole	parts per trillion	no guideline	<2	<2	Common taste and odour compound
236 TCA - 2,3,6-trichloroanisole	parts per trillion	no guideline	<2	<2	Common taste and odour compound
345 TCV - 3,4,5-trichloroveratrole	parts per trillion	no guideline	<2	<2	Common taste and odour compound
Plankton (algae) count	cells per millilitre	no guideline	22,300	900 to 271,000	Algae contribute to odours and may cause filter clogging
Chlorophyll-a	parts per billion	no guideline	5.8	3 to 17	Chlorophyll is found in algae
Microcystin LR	parts per billion	no more than 1.5	<0.2	<0.2	Raw water - guideline does not apply
Cryptosporidium	oocysts per 100 litres	no guideline	<2	<0.7 to <2	14 samples taken in 2004 - no positive results
Giardia	cysts per 100 litres	no guideline	<2	<2	14 samples taken in 2004 - no positive results
Turbidity (clearness)	units	no more than 1.0	0.6	0.25 to 1.50	Raw water - guideline does not apply
Colour, Apparent	units	no guideline	6	3 to 10	Coloured water may be offensive
Total Dissolved Solids	parts per million	no more than 500	106	70 to 146	Raw water - guideline does not apply
Conductivity	microsiemens per centimetre	no guideline	148	135 to 178	Another measure of dissolved solids
pH	units	between 6.5 and 8.5	8.26	7.81 to 9.19	Raw water - guideline does not apply
Total Alkalinity	parts per million as calcium carbonate	no guideline	75	68 to 85	-
Total Hardness	parts per million as calcium carbonate	no guideline	76	68 to 84	80 to 100 parts per million is recommended
Total Organic Carbon	parts per million	no guideline	9	8 to 11	-
Soluble Organic Carbon	parts per million	no guideline	9	8 to 10	-
Total Kjeldahl Nitrogen (TKN)	parts per million	no guideline	0.46	0.31 to 0.63	TKN is a combination of ammonia and organic nitrogen
Total Phosphorus	parts per million	no guideline	0.014	0.012 to 0.018	Phosphorus can contribute to algae growth
Total Soluble Phosphorus	parts per million	no guideline	0.003	0.002 to 0.004	-
Fluoride	parts per million	no more than 1.5	0.08	0.07 to 0.10	Naturally occurring fluoride in Shoal Lake
Nitrate	parts per million	no more than 10	0.07	0.05 to 0.09	Raw water - guideline does not apply
Chloride	parts per million	no more than 250	<9	<9	Raw water - guideline does not apply
Sulphate	parts per million	no more than 500	<9	<9	Raw water - guideline does not apply
Trihalomethanes	parts per billion	no more than 100	<0.5	<0.5	Raw water - guideline does not apply
Haloacetic acids	parts per billion	no guideline	<2	<2	-
Calcium	parts per million	no guideline	20.1	18.9 to 22.4	Contributes to hardness
Magnesium	parts per million	no guideline	6.17	5.18 to 8.85	Contributes to hardness
Sodium	parts per million	no more than 200	2.3	1.70 to 4.60	Raw water - guideline does not apply
Potassium	parts per million	no guideline	1.1	0.90 to 1.30	-
Iron	parts per million	no more than 0.30	0.03	0.02 to 0.04	Raw water - guideline does not apply
Copper	parts per million	no more than 1.0	<0.001	<0.001	Raw water - guideline does not apply
Lead	parts per million	no more than 0.010	<0.001	<0.001	Raw water - guideline does not apply
Aluminum	parts per million	no guideline	0.004	0.002 to 0.006	-
Arsenic	parts per million	no more than 0.025	<0.001	<0.001 - 0.001	Raw water - guideline does not apply
Chromium	parts per million	no more than 0.05	<0.001	<0.001	Raw water - guideline does not apply
Nickel	parts per million	no guideline	<0.001	<0.001	-
Cadmium	parts per million	no more than 0.005	<0.001	<0.001	Raw water - guideline does not apply
Manganese	parts per million	no more than 0.05	0.007	0.003 - 0.010	Raw water - guideline does not apply
Zinc	parts per million	no more than 5.0	<0.001	<0.001	Raw water - guideline does not apply

Guidelines from 'Summary of Guidelines for Canadian Drinking Water Quality' by Health Canada, March 2001

This page is printer friendly.
Top of page	This page was last updated on April 15, 2024