2005 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	units	Inoffensive	125	35 to >200	Raw water - guideline does not apply
Geosmin	parts per trillion	no guideline	4	<2 to 7	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	<2	<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	88,800	690 to 641,000	Algae contribute to odours and may cause filter clogging
Chlorophyll-a	parts per billion	no guideline	8.3	<1 to 19.6	Chlorophyll is found in algae
Microcystin LR	parts per billion	no guideline	<0.2	<0.2	Raw water - guideline does not apply
Cryptosporidium	oocysts per 100 litres	no guideline	<2	<2	23 samples taken in 2005 - no positive results
Giardia	cysts per 100 litres	no guideline	<2	<2	23 samples taken in 2005 - no positive results
Turbidity (clearness)	Nephelometric turbidity units	no more than 1	0.75	0.25 to 1.85	Raw water - guideline does not apply
Colour, Apparent	units	no more than 15	6.9	5 to 12.5	Coloured water may be offensive
Total Dissolved Solids	parts per million	no more than 500	101	97 to 107	Raw water - guideline does not apply
Conductivity	microsiemens per centimetre	no guideline	145	130 to 178	Another measure of dissolved solids
pH	units	between 6.5 and 8.5	8.15	7.38 to 8.8	Raw water - guideline does not apply
Temperature	degrees Celsius	no more than 15	9.8	1.5 to 22.5	Raw water - guideline does not apply
Total Alkalinity	parts per million as calcium carbonate	no guideline	73	67 to 82	-
Total Hardness	parts per million as calcium carbonate	no guideline	73	68 to 79	80 to 100 parts per million is recommended
Total Organic Carbon	parts per million	no guideline	10	8 to 11	-
Soluble Organic Carbon	parts per million	no guideline	9	8 to 11	-
Total Kjeldahl Nitrogen (TKN)	parts per million	no guideline	0.47	0.33 to 0.63	TKN is a combination of ammonia and organic nitrogen
Total Phosphorus	parts per million	no guideline	0.016	0.011 to 0.025	Phosphorus can contribute to algae growth
Total Soluble Phosphorus	parts per million	no guideline	<0.002	<0.002 to 0.004	-
Fluoride	parts per million	no more than 1.5	<0.1	<0.1	Raw water - guideline does not apply
Nitrate	parts per million	no more than 10	<0.04	<0.04 to 0.07	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 to 9	Raw water - guideline does not apply
Trihalomethanes a	parts per billion	no more than 100	<0.5	<0.5	Raw water - guideline does not apply
Bromodichloromethane a	parts per billion	no more than 16	<0.5	<0.5	Raw water - guideline does not apply
Haloacetic acids	parts per billion	no guideline	<1.0	<1.0	-
Calcium	parts per million	no guideline	20.3	19 to 20.7	Contributes to hardness
Magnesium	parts per million	no guideline	5.71	5.38 to 5.91	Raw water - guideline does not apply
Sodium	parts per million	no more than 200	1.98	1.87 to 2.14	Raw water - guideline does not apply
Potassium	parts per million	no guideline	1.23	1.17 to 1.31	Raw water - guideline does not apply
Iron	parts per million	no more than 0.3	0.03	<0.01 to 0.05	Raw water - guideline does not apply
Copper	parts per million	no more than 1.0	<0.001	<0.001 to 0.005	Raw water - guideline does not apply
Lead	parts per million	no more than 0.01	<0.001	<0.001 to 0.006	Raw water - guideline does not apply
Aluminum	parts per million	no more than 0.2	0.004	<0.001 to 0.007	Raw water - guideline does not apply
Arsenic	parts per million	no more than 0.025	0.001	<0.001 to 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 to 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	<0.01	<0.01 to 0.02	Raw water - guideline does not apply
Zinc	parts per million	no more than 5.0	<0.003	<0.003	Raw water - guideline does not apply

(a) Guidelines for Canadian Drinking Water Quality: Guideline Technical Document, Trihalomethanes, May 2006.
Guidelines from 'Summary of Guidelines for Canadian Drinking Water Quality' by Health Canada, March 2006.

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