VULNERABILITY OF SURFACE WATER
Physical vulnerability of withdrawal site
(1) The physical vulnerability of the withdrawal site must be assessed using the most restrictive of the following methods:
(1) a historical review of all the natural or anthropic events recorded pursuant to section 22.0.4 of the Regulation respecting the quality of drinking water (chapter Q-2, r. 40), over a consecutive 5-year period, that may have affected the condition of the withdrawal site, allowing water vulnerability to be rated as follows:
(a) high if more than 1 distinct event is recorded;
(b) medium if a single distinct event is recorded;
(c) low if no events are recorded;
(2) a high rating assessment by a professional who certifies in writing that the location of the withdrawal site is a cause for concern because of the hydro-dynamic characteristics of the body of water, of water extraction, development or harnessing projects upstream, of a forecast increase in water demand, or of the anticipated effects of climate change.
Water vulnerability to microorganisms
(2) Water vulnerability to microorganisms is assessed using one of the following methods:
(1) a compilation, over a consecutive 5-year period, of the results of an analysis of raw water samples withdrawn in accordance with the Regulation respecting the quality of drinking water for Escherichia coli bacteria, including the samples taken pursuant to section 22.0.1. The compilation is used to rate water vulnerability as follows:
(a) high if the analysis results show a median value above 150 UFC/100 ml or if the value of the 95th percentile is above 1 500 UFC/100 ml;
(b) medium if vulnerability is neither low nor high;
(c) low if the analysis results show a median value below 15 UFC/100 ml and if the value of the 95th percentile is below 150 UFC/100 ml;
(2) when the method in paragraph 1 cannot be used, water vulnerability is rated as follows:
(a) high, if the inner protection zone for the withdrawals is wholly situated in an urban area, or if at least one overflow from a combined or semi-separated sewer system likely to discharge raw or partially untreated sewage following a storm, continuous rain or a snow melt is located in the inner or intermediate protection zone;
(b) medium if vulnerability is neither low nor high;
(c) low, if the withdrawal site is situated downstream from an agglomeration served by a combined or semi-separated sewer system, a livestock raising operation, a food processing industry or another establishment likely to discharge pathogenic microorganisms or microorganisms indicating a contamination of fecal origin into the watercourse.
Water vulnerability to fertilizers
(3) Water vulnerability to fertilizers is assessed using the most restrictive of the following methods:
(1) a compilation, over a consecutive 5-year period, of the results of an analysis of raw water samples withdrawn in accordance with section 22.0.1 of the Regulation respecting the quality of drinking water for total phosphorous. The compilation is used to rate water vulnerability as follows:
(a) in a lake:
i. high if the average result is equal to or greater than 20 µg/l P;
ii. medium if the average result is between 10 µg/l P and 20 µg/l P;
iii. low if the average result is equal to or les than 10 µg/l P;
(b) in any other watercourse:
i. high if the average result is equal to or greater than 50 µg/l P;
ii. medium if the average result is between 30 µg/l P and 50 µg/l P;
iii. low if the average result is equal to or less than 30 µg/l P;
(2) a historical review of all events recorded pursuant to section 22.0.4 of the Regulation respecting the quality of drinking water in a watercourse over a consecutive 5-year period involving cyanobacteria, algae or aquatic plant proliferations or increases in ammoniacal nitrogen, allowing water vulnerability to be rated as follows:
(a) high if 5 or more events are recorded;
(b) medium if 2 to 4 events are recorded;
(c) low if 1 or no events are recorded;
(3) when the methods in paragraphs 1 and 2 cannot be used, water vulnerability must be assessed by a professional based on the potential impact of anthropic activities recorded in the outer protection zone for the water withdrawals in terms of the introduction of fertilizers that may affect the water withdrawn.
Water vulnerability to turbidity
(4) Vulnerability to turbidity must be assessed using one of the following methods:
(1) a compilation, over a consecutive 5-year period, of the results of an analysis of raw water samples withdrawn in accordance with section 22.0.2 of the Regulation respecting the quality of drinking water for turbidity. The compilation is used to rate water vulnerability as follows:
(a) high if the value of the 99th percentile is equal to or greater than 100 NTU (nephelometric turbidity unit);
(b) low in other cases;
(2) when the method in paragraph 1 cannot be used, water vulnerability must be assessed by a professional based on the potential impact of the natural characteristics of the outer protection zone for the water withdrawals and human acitivites carried out on water turbidity.
Water vulnerability to inorganic substances
(5) Vulnerability to inorganic substances must be assessed using one of the following methods:
(1) a compilation, over a consecutive 5-year period, of the results of an analysis of water supply samples withdrawn in accordance with section 14 of the Regulation respecting the quality of drinking water for inorganic substances associated with the source. The compilation is used to rate water vulnerability as follows:
(a) high if, for at least one substance, 2 of the values analyzed are equal to or greater than 50% of the applicable standard;
(b) medium if
i. for at least one substance, 2 of the values analyzed are between 20% and 50% of the applicable standard;
ii. for at least one substance, 1 of the values analyzed is between 20% and 50% of the applicable standard and 1 other value is equal to or greater than 50% of the applicable standard;
(c) low in other cases;
(2) when the method in paragraph 1 cannot be used, the total of all the areas used for industrial, commercial or agricultural activities in the strips of land 120 m wide in the intermediate protection zone delimited for water withdrawals is used to rate water vulnerability as follows:
(a) high, if the total is equal to or greater than 50% of the total area of the strips of land 120 m wide in the intermediate protection zone;
(b) medium, if the total area is between 20% and 50% of the total area of the strips of land 120 m wide in the intermediate protection zone;
(c) low, if the total area is equal to or less than 20% of the total area of the strips of land 120 m wide in the intermediate protection zone.
Water vulnerability to organic substances
(6) Vulnerability to organic substances must be assessed using one of the following methods:
(1) a compilation, over a consecutive 5-year period, of the results of an analysis of water supply samples withdrawn in accordance with section 19 of the Regulation respecting the quality of drinking water for inorganic substances associated with the source. The compilation is used to rate water vulnerability as follows:
(a) high if, for at least one substance, 2 of the values analyzed are equal to or greater than 50% of the applicable standard;
(b) medium if
i. for at least one substance, 2 of the values analyzed are between 20% and 50% of the applicable standard;
ii. for at least one substance, 1 of the values analyzed is between 20% and 50% of the applicable standard and 1 other value is equal to or greater than 50% of the applicable standard;
(c) low in other cases;
(2) when the method in paragraph 1 cannot be used, the total of all the areas used for industrial, commercial or agricultural activities in the strips of land 120 m wide in the intermediate protection zone delimited for water withdrawals is used to rate water vulnerability as follows:
(a) high, if the total is equal to or greater than 50% of the total area of the strips of land 120 m wide in the intermediate protection zone;
(b) medium, if the total area is between 20% and 50% of the total area of the strips of land 120 m wide in the intermediate protection zone;
(c) low, if the total area is equal to or less than 20% of the total area of the strips of land 120 m wide in the intermediate protection zone.