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State of the Water Quality

The state of the water quality was judged by comparing values to the Ministry of Environment, Lands and Parks' Approved and Working Criteria for Water Quality (Nagpal et al., 1995). Indicators not discussed below met their criteria and did not display any environmentally significant trends. These include: barium, beryllium, total inorganic carbon, chloride, cobalt, fluoride, lithium, magnesium, molybdenum, nickel, nitrate/nitrite, total dissolved nitrogen, pH, total phosphorus, potassium, filterable residue, fixed filterable residue, fixed non-filterable residue, silica, sodium, specific conductivity, strontium, sulphate, air temperature, and vanadium.

Flow (Figure 2) values were highest during spring freshet (May-July). Peak flow values were similar in most years except for higher values in 1988 and 1990. The lowest peak values occurred in 1989 and 1993.

Total alkalinity (Figure 3) and calcium (Figure 9) concentrations indicate a low sensitivity to acid inputs.

Total aluminum (Figure 4) values exceeded the 5 mg/L total aluminum criterion for wildlife, livestock and irrigation 10% of the time. Peak aluminum values corresponded to peak non-filterable residues and turbidity. This suggests that the aluminum was in a particulate form and probably not biologically available and would be removed by the turbidity removal needed before drinking. Dissolved aluminum should also be measured for direct comparison to criteria for drinking water and aquatic life.

Total arsenic (Figure 5) exceeded the 0.005 mg/L proposed criterion for aquatic life 8% of the time. These values occurred at the same time as high non-filterable residues and turbidity. This indicates that the arsenic was in a particulate form and probably not biologically available.

Total cadmium (Figure 8) values between 1986 and 1991 were questionable due to suspected preservative vial contamination. Minimum detectable limits (0.0001 mg/L & 0.001 mg/L) were 2 to 33 times above the aquatic life criteria (0.00003 mg/L to 0.00006 mg/L). Peak cadmium values corresponded to peak periods of non-filterable residues and turbidity. This indicates that the cadmium was in a particulate form and not biologically available. To evaluate the aquatic life criteria accurately, the minimum detectable limit should be lowered to at least one-tenth of the lowest criterion, and dissolved cadmium should also be measured.

Total organic carbon (Figure 11) exceeded the 4 mg/L drinking water criterion 44% of the time. Most of the higher values corresponded to elevated non-filterable residue and turbidity, suggesting that the carbon was in a particulate form and would be removed by the turbidity removal needed before drinking.

Total chromium (Figure 13) values in 1990 were high due to preservative vial contamination. Since then, one value (June 27, 1995) exceeded the 0.02 mg/L aquatic life criterion for fish, and 40% of the values exceeded the 0.002 mg/L aquatic life criterion for phyto- and zoo-plankton. High chromium values corresponded to high non-filterable residues and turbidity. This indicates that the chromium was in a particulate form and probably not biologically available.

Apparent colour (Figure 15) met the 100-unit recreation (maximum) criterion at least 89% of the time. Also, the 15-unit drinking water and recreation criterion was met 45% of the time. All criteria are given as true colour values, where turbidity is removed before measurement. Most of the high apparent colour values occurred in samples with high turbidity, and thus true colour would have been much lower. True colour should be measured to compare the data to the criteria effectively.

Total copper (Figure 16) values were high between 1986 and 1991 due to preservative vial contamination. Outside this period, 14% of the values exceeded the upper (0.009 mg/L) aquatic life criterion, and 51% of the values exceeded the lower (0.002 mg/L) aquatic life criterion. High copper and non-filterable residues and turbidity occurred together during peak flows. This indicates that the copper was in a particulate form and probably not biologically available.

Hardness (Figure 18) values were above the optimum range for drinking water (80-100 mg/L as CaCO3) 94% of the time, and reached the poor, but still tolerable, level (200 mg/L) during the winter.

Total iron (Figure 19) exceeded the 5 mg/L irrigation criterion 18% of the time, while the 0.3 mg/L drinking water and aquatic life criterion was exceeded 69% of the time. High values of iron corresponded with high non-filterable residues and turbidity. This indicates that the iron was in a particulate form and probably not biologically available and would be removed by the turbidity removal needed before drinking.

Total lead (Figure 20) values between 1986 and 1991 were questionable due to suspected preservative vial contamination. Outside this period, the 0.01 mg/L drinking water criterion was exceeded twice (June 17, 1991 and June 29, 1993). Also, the 0.005 mg/L aquatic life lower criterion was exceeded by 16% of the values. High lead and non-filterable residues and turbidity occurred together during high flow. This indicates that the lead was in a particulate form and probably not biologically available and would be removed by the turbidity removal needed before drinking.

Total manganese (Figure 23) exceeded the 0.2 mg/L criterion for irrigation 7% of the time. Also, the 0.1 mg/L criterion for aquatic life was exceeded 17% of the time, and the 0.05 mg/L criterion for drinking water was exceeded 37% of the time. High manganese and non-filterable residues and turbidity occurred together during periods of high flow. This indicates that the manganese was in a particulate form and probably not biologically available and would be removed by the turbidity removal needed before drinking.

Non-filterable residue (Figure 32) exceeded the 25 mg/L criterion for good fisheries 64% of the time, particularly during high flows. The patterns of non-filterable residue and turbidity (Figure 43) were very similar.

Total selenium (Figure 35) values exceeded the 0.001 mg/L criterion for aquatic life 8% of the time. Most of these values (7 of 10) occurred when non-filterable residue and turbidity were high, suggesting that the selenium may have been in a particulate form and not bio-available. However, the other three values occurred when non-filterable residue was low to moderate (0 to 100 mg/L). Dissolved and total selenium should be measured in the future.

Water temperature (Figure 42) exceeded the 15°C aesthetic limit for drinking water and the lower limit for recreation 19% of the time, with all peak temperatures occurring between June and August. This means that the water was cool enough to be aesthetically pleasing for drinking, except during the summer, when it was warm enough for water-contact recreation such as swimming. However, the water temperatures warm enough for swimming often occurred when turbidity exceeded the criterion for recreation.

Turbidity (Figure 43) values exceeded the 50 NTU criterion for recreation 22% of the time, mainly during freshet. The 5 NTU aesthetic criterion for drinking water was exceeded 61% of the time, and the 1 NTU health criterion for drinking water was exceeded 78% of the time. Turbidity removal and disinfection are needed prior to drinking.

Total zinc (Figure 45) exhibited high values between 1986 and 1991, which may have been due to suspected preservative vial contamination. Outside this period, 18% of the values exceeded the 0.03 mg/L fish and invertebrates criterion, and 31% exceeded the 0.015 mg/L algae criterion. Peak zinc values corresponded to peak non-filterable residue and turbidity. This indicates that the zinc was in a particulate form and probably not biologically available.

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