The state of the water quality is 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 the criteria and did not display any noticeable trends. These include: barium, beryllium, total inorganic carbon, chloride, cobalt, lithium, magnesium, molybdenum, nickel, nitrate/nitrite, total dissolved nitrogen, total phosphorus, potassium, filterable residue, fixed filterable residue, fixed non-filterable residue, selenium, silica, sodium, conductivity, strontium, sulphate and vanadium.
Flow (Figure 2) values were highest during spring freshet (May-July). Peak flow values were similar most years except for lower peak values in 1989 and 1991.
Total aluminum (Figure 4) values met the 0.2 mg/L criterion for drinking water at least 77% of the time. Also, at least 58% of the values met the 0.1 mg/L maximum criterion for aquatic life, and at least 40% of the values met the 0.05 mg/L average criterion for aquatic life. However, all these criteria are for dissolved aluminum. Total aluminum values are not directly comparable to dissolved criteria because dissolved aluminum values in the water column are much lower than total aluminum. For direct comparison to these criteria, dissolved aluminum should be measured. Peak aluminum values corresponded to peak non-filterable residue and turbidity values. This suggests that the aluminum was in a particulate form and was probably not biologically available and would be removed by the turbidity removal needed before drinking.
Total arsenic (Figure 5) had one value (July 20, 1988) that slightly exceeded the 0.005 mg/L proposed aquatic life criterion.
Total cadmium (Figure 8) values were high between 1986 and 1991 due to suspected preservative vial contamination. Minimum detectable limits (0.0001 mg/L, 0.0005 mg/L, and 0.001 mg/L) were 2 to 33 times above the aquatic life criteria (0.00003 mg/L to 0.00006 mg/L). Since 1991, cadmium was detected 13 times at levels above the aquatic life criteria. Some of the detectable values corresponded to elevated turbidity and thus the cadmium may have been in a particulate form and not bio-available. Other detectable values may have been false positives close to the detection limit. To evaluate the criteria for aquatic life 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 criterion for drinking water twice (August 20, 1987 and December 27, 1994).
Total chromium (Figure 13) values in 1990 may have been high due to preservative vial contamination. Since then, 9% of the values exceeded the 0.002 mg/L criterion for phyto- and zoo-plankton. The chromium values above the criterion did not normally correspond to high turbidity or non-filterable residue, and thus may have been in a bio-available form. Total chromium levels above the 0.002 mg/L criterion were found at many of the federal-provincial water quality stations in B.C., and thus they may be a natural occurrence or due to network-wide artificial contamination (Pommen, 1996). Total and dissolved chromium should be measured.
Apparent colour (Figure 15) was highest during the summer months and near the minimum detectable limit (5 units) during the winter months. The 15-unit true colour drinking water and recreation criterion was met at least 88% of the time. The high apparent colour values occurred in samples with high turbidity, and true colour would have been much lower because turbidity is removed before measurement. 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. Since early 1991, the aquatic life criteria have been met.
Dissolved fluoride (Figure 17) exceeded the lower (0.2 mg/L) criterion for aquatic life once (February 4, 1993, with a hardness of 48.1 mg/L).
Hardness (Figure 18) values were within the optimum range for drinking water (80-100 mg/L as CaCO3) 32% of the time. Fifty-four percent of the values were above this range and 14% were below. During most winters, hardness exceeded 200 mg/L for short periods. Levels of more than 200 mg/L are rated as poor for drinking, but still tolerable. Lowest hardness occurred in the summer and highest values occurred in the winter. Higher flow leads to increased dilution of dissolved constituents such as hardness, while lower flow results in less dilution and higher hardness values.
Total iron (Figure 19) values exceeded the 5 mg/L criterion for irrigation once (May 5, 1989). Also, 35% of the values were above the 0.3 mg/L drinking water and aquatic life criteria. High values of iron and turbidity occurred together. Thus, the iron was probably in a particulate form and not biologically available and would be removed by treatment needed to remove turbidity prior to drinking.
Total lead values (Figure 20) were high between 1986 and 1991 due to preservative vial contamination. Since 1991, all criteria have been met.
Total manganese (Figure 23) values exceeded the 0.1 mg/L aquatic life criterion three times (February 25, 1988, May 5, 1989 and May 30, 1990) and the 0.05 mg/L drinking water criterion 8% of the time. High manganese and turbidity usually occurred together between 1987 and 1992. Thus, the manganese was probably in a particulate form and not biologically available. Also, the manganese would probably be removed by the treatment needed to remove turbidity prior to drinking.
pH (Figure 28) was low between 1986 and 1988 because of laboratory control problems. One value (April 21, 1989) exceeded the 8.5-unit upper aesthetic limit for drinking water. All other values met criteria.
Non-filterable residue (Figure 32) values exceeded the 25 mg/L criterion for good fisheries 19% of the time during peak flows.
Air temperature (Figure 41) had no freezing temperatures prior to about 1990, indicating a systematic error in measuring or recording air temperature.
Water temperature (Figure 42) exceeded the 15°C upper aesthetic limit for drinking water and the lower limit for recreation 4% of the time. This means that the water is cool enough to be aesthetically pleasing for drinking, but too cold for water-contact recreation such as swimming.
Turbidity (Figure 43) values exceeded the 5 NTU aesthetics criterion for drinking water 13% of the time and the 1 NTU health criterion for drinking water 46% of the time during peak flows. Turbidity removal and disinfection are needed prior to use for drinking water.
Total zinc (Figure 45) had high values between 1986 and 1991 due to preservative vial contamination. Outside of that period, the 0.015 mg/L algae criterion was exceeded three times (November 11, 1991, April 18, 1992 and June 15, 1992), but the criterion for fish and invertebrates was met. Two of the three higher values corresponded to elevated turbidity, indicating that the zinc was in a particulate form and probably not bio-available.