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2003 Shoal Lake water quality test results

Image of Shoal Lake inletOur 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 106 50 to more than 200 Raw water - guideline does not apply
Geosmin parts per trillion no guideline 5 <1 to 16 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 <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 20,006 1630 to 126400 Algae contribute to odours and may cause filter clogging
Chlorophyll-a parts per billion no guideline 5.1 1.7 to 8.9 Chlorophyll is found in algae
Microcystin LR parts per billion no more than 1.5 <0.07 <0.07 Raw water - guideline does not apply
Cryptosporidium oocysts per 100 litres no guideline <0.4 <1.0 to 0.5 15 samples taken in 2003 - one positive result
Giardia cysts per 100 litres no guideline <0.9 <0.5 to <1.0 15 samples taken in 2003 - no positive results
Turbidity (clearness) units no more than 1.0 0.85 0.15 to 1.50 Raw water - guideline does not apply
Colour, Apparent units no guideline 7 5 to 12.5 Coloured water may be offensive
Total Dissolved Solids parts per million no more than 500 100 70 to 142 Raw water - guideline does not apply
Conductivity microsiemens per centimetre no guideline 160 138 to 203 Another measure of dissolved solids
pH units between 6.5 and 8.5 8.2 7.1 to 9.3 Raw water - guideline does not apply
Total Alkalinity parts per million as calcium carbonate no guideline 77 71 to 89  -
Total Hardness parts per million as calcium carbonate no guideline 77 69 to 92 80 to 100 parts per million is recommended
Total Organic Carbon parts per million no guideline 9 7 to 12  -
Soluble Organic Carbon parts per million no guideline 9 7 to 12  -
Total Kjeldahl Nitrogen (TKN) parts per million no guideline 0.61 0.46 to 0.92 TKN is a combination of ammonia and organic nitrogen
Total Phosphorus parts per million no guideline 0.015 0.012 to 0.022 Phosphorus can contribute to algae growth
Total Soluble Phosphorus parts per million no guideline 0.004 <0.002 to 0.005  -
Fluoride parts per million no more than 1.5 0.08 0.07 to 0.09 Naturally occurring fluoride in Shoal Lake
Nitrate parts per million no more than 10 0.11 <0.04 to 0.15 Raw water - guideline does not apply
Chloride parts per million no more than 250 <5 <5 Raw water - guideline does not apply
Sulphate parts per million no more than 500 <5 <5 to <10 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 20.9 18.3 to 25 Contributes to hardness
Magnesium parts per million no guideline 5.78 4.83 to 7.20 Contributes to hardness
Sodium parts per million no more than 200 2.14 1.80 to 2.60 Raw water - guideline does not apply
Potassium parts per million no guideline 1.39 1.14 to 1.80  -
Iron parts per million no more than 0.30 0.05 0.03 to 0.07 Raw water - guideline does not apply
Copper parts per million no more than 1.0 <0.001 <0.001 to 0.002 Raw water - guideline does not apply
Lead parts per million no more than 0.010 <0.002 <0.002 Raw water - guideline does not apply
Aluminum parts per million no guideline 0.005 0.003 to 0.007  -
Arsenic parts per million no more than 0.025 <0.001 to <0.002 <0.002 Raw water - guideline does not apply
Chromium parts per million no more than 0.05 0.0003 <0.0003 to 0.0003 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 <0.00005 <0.00005 to <0.001 Raw water - guideline does not apply
Manganese parts per million no more than 0.05 0.009 <0.050.008 to 0.009 Raw water - guideline does not apply
Zinc parts per million no more than 5.0 <0.002 <0.002 Raw water - guideline does not apply

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

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This page was last updated on April 24, 2017