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Water Quality

State of Water Quality of Quamichan Lake 1988-1995

Canada - British Columbia Water Quality Monitoring Agreement

Water Quality Section
Water Management Branch
Ministry of Environment, Lands and Parks

April, 1996


Executive Summary

Quamichan Lake is located on southern Vancouver Island 3 km east of Duncan, B.C. (Figure 1). The watershed for this large, shallow lake is 16.3 km².

This report assesses 5 years of water quality data, 21 years (1973-1995) of fecal coliform data, and makes the following conclusions:

We recommend that a remediation plan be developed and implemented to improve water quality in Quamichan Lake.

We recommend monitoring:

Both monitoring programs could be implemented by the Ministry of Environment, Lands and Parks with assistance from a Quamichan Lake stewardship group.

The monitoring program will continue to be implemented at Art Mann Beach by the Central Vancouver Island Health Unit.

The monitoring program should be implemented by the Central Vancouver Island Health Unit, or by a Quamichan Lake stewardship group.


Figure 1 Quamichan Lake Watershed
Scale 1:50,000


Table of Contents

Executive Summary
Acknowledgements
Introduction
Quality Assurance
State of the Water Quality

Spring Overturn

Conclusions - State of Water Quality
Recommendations for Water Quality Management

Remediation
Monitoring

References

List of Figures

Figure 1 Quamichan Lake Watershed
Figure 2 Bathymetric Map of Quamichan Lake
Figure 3 Total Phosphorus (average in the water column before stratification) from Quamichan Lake
Figure 4 Total phosphorus from Quamichan Lake
Figure 5 Total dissolved phosphorus from Quamichan Lake
Figure 6 Dissolved ammonia from Quamichan Lake
Figure 7 Kjeldahl nitrogen from Quamichan Lake
Figure 8 N:P Ratio from Quamichan Lake
Figure 9 Total calcium from Quamichan Lake
Figure 10 True colour from Quamichan Lake
Figure 11 Total aluminum from Quamichan Lake
Figure 12 Total copper from Quamichan Lake
Figure 13 Total iron from Quamichan Lake
Figure 14 Total manganese from Quamichan Lake
Figure 15 Total residues from Quamichan Lake
Figure 16 Specific conductivity from Quamichan Lake
Figure 17 Dissolved silica from Quamichan Lake
Figure 18 Total zinc from Quamichan Lake
Figure 19 pH from Quamichan Lake

List of Tables

Table 1 Summary of water quality data from Quamichan Lake (SEAM site E207465)
Table 2 Summary of Central Vancouver Island Health Unit's Bacteriological data (fecal coliform/100 mL) from Quamichan Lake (Art Mann Park)


Author

Holms, G. Bruce B.Sc. Research Officer. Water Quality Branch, Environmental Protection Department, Victoria, B.C.

Acknowledgements

Drafts of this report were sent to Lloyd Erickson and John Deniseger, Environmental Protection in Nanaimo, Brian Dennison, Cowichan Valley Regional District, Gary Smith, Central Vancouver Island Health Unit, Barry Boettger, Public Health Protection, Rick Nordin and Larry Pommen, Water Quality Branch, Andrea Ryan, Environment Canada, Gayle Jackson, Corporation of the District of North Cowichan, and Dr. Stan Polack. Valuable comments were provided and incorporated into this report.


Introduction

Quamichan Lake is located on southern Vancouver Island 3 km east of Duncan, B.C. (Figure 1). The watershed for this large, shallow lake is 16.3 km² (Willis, Cunliffe, and Tait, 1979). The surface area of Quamichan Lake is 313.4 ha (Figure 2) with a maximum depth of 8.2 m and a mean depth of 4.7 m (Klein and Heathman, 1972).

Quamichan Lake has two seasonal inlet streams (MacIntyre and Elkington Creeks). These creeks enter the east end of the lake (Yaworski, 1986). Quamichan Creek flows west and drains into the Cowichan River.

The Ministry of Environment, Lands and Parks monitored the water quality at the deepest point (8 m) of the lake between 1988 and 1995. The data are stored on the provincial data base, SEAM, under station number E207465 (Figure 1). The two purposes for monitoring the water quality of Quamichan Lake are to identify:

The Central Vancouver Island Health Unit collected fecal coliform samples from a bathing beach (Art Mann Park) on Quamichan Lake. Weekly sampling begins in April each year and continues through the bathing season, ending in September. Fecal coliform results from five samples collected within a 30-day period are used to establish a geometric mean at the beginning of the season. A beach advisory notice, warning of the potential for increased risk to bathers' health, is considered for posting if the geometric mean exceeds 200 fecal coliforms/100 mL over a 30-day period. More intense sampling may occur if the results of a single sample exceeds 400 fecal coliforms/100 mL.

This report assesses 5 years (1988-1995) of spring overturn water quality sampling, and 21 years (1973-1995) of fecal coliform sampling. The water quality data are plotted in Figures 3 to 19 and summarized in Table 1 and Table 2.

The box plots, used in Figures 3 to 19, represent the variability of water quality indicators collected at the surface, mid-depth, and near the bottom of the lake. Each plot is comprised of a rectangle with the top portraying the upper quartile (75th percentile of the data series, Q(0.75)), the bottom portraying the lower portion (25th percentile of the data series, Q(0.25)), and a horizontal line within the rectangle portraying the median. Vertical lines extend from the ends of the rectangle to the adjacent values, also known as "whiskers", and are defined by:

Values that fall outside the range of the adjacent values are defined as "outside values" and are plotted as asterisks (*). Values are defined as "far outside values" if they are located outside the outer range which is defined as the upper quartile plus 3 X IQR or the lower quartile minus 3 X IQR. These values are plotted as empty circles (O).

Trends in water quality data collected at different depths and at different frequencies over time are assessed by comparing yearly changes in median values in conjunction with the size of sample variability. The size of sample variability is represented in the box plots by the rectangle, whiskers, and the two types of outliers. A change is observed when the median values and sample variability do not overlap.


Quality Assurance

The water quality plots were reviewed. Samples collected on May 14, 1992 at the surface and at a depth of 3 m from Quamichan Lake contained:

The total phosphorus value collected on October 7, 1992 and the total dissolved phosphorus value collected on May 14, 1992 were "far outside values" (Figures 4 and 5), and are considered as questionable values.


State of the Water Quality

The state of the water quality is assessed by comparing the values to any site-specific water quality objectives or to Ministry of Environment, Lands and Parks' Approved and Working Criteria for Water Quality (Nagpal et al., 1995) if objectives have not been set. Any levels or trends in water quality that are deleterious to sensitive water uses, including drinking water, aquatic life and wildlife, recreation, irrigation, and livestock watering are noted.

Water from Quamichan Lake is used for irrigation, water-based recreation, and to sustain aquatic life. There are 24 domestic water licences that may be used as a drinking water source.


Figure 2 Bathymetric Map of Quamichan Lake


Spring Overturn

The water in Quamichan Lake is vertically mixed (no thermal stratification) between November and the end of April. A key time for sampling is late during this period of mixing. The objective of this monitoring is to assess water quality from year to year and to estimate the potential algal growth during the summer months in Quamichan Lake.

Total Phosphorus (Figure 3) values before thermal stratification, average of samples taken at different depths within the water column, were outside the limits (0.005-0.015 mg/L) for aquatic life in 1992 and 1993. These values were within the limits for aquatic life after 1993. Total phosphorus values before thermal stratification exceeded the criteria for drinking water and protecting recreational use (0.010 mg/L) in 1992, 1993, and 1995.

Total phosphorus (Figures 3 and 4) and total dissolved phosphorus values (Figure 5) generally decreased between 1992 and 1995. This decrease of phosphorus in the water column may be attributed to several factors including:

Nitrogen, Dissolved ammonia (Figure 6) values were below the criterion (30-day average of 1.83 mg/L) to protect aquatic life from toxicity. 75% of the values collected between 1993 and 1995 were less than the minimum detectable limit (0.005 mg/L). Dissolved ammonia values have decreased between 1988 and 1995. 94% of the Nitrate/nitrite values equalled or were less than the minimum detectable limit (0.02 mg/L). Kjeldahl nitrogen (Figure 7) and nitrite/nitrate concentrations are added together to represent total nitrogen in the lake. These concentrations are used to calculate the N:P ratio (Figure 8). The N:P ratios were highly variable between 1988 and 1995, and increased after 1993. Phosphorus is the limiting nutrient for algal growth (N:P > 15:1) in Quamichan Lake (Figure 8). The trends in the ratios indicate that there are changes occurring in the lake systems (e.g., land use, flushing rate, biological activity) which affect water quality.

Total calcium (Figure 9) values of total calcium increased over time, and the lake has a low sensitivity to acid inputs (the lake is well buffered).

Fecal coliform values were collected for 21 years (between 1973 and 1991, and between 1994 and 1995) from a beach site at Art Mann Park on Quamichan Lake (Table 2). These values ranged from less than 3 MPN/100 mL to > 7000 MPN/100 mL. Fecal coliform values from this beach site may not be similar to values collected elsewhere in the lake. Factors such as resident waterfowl populations make this area unique and may cause fecal coliform values to be higher than at other sites in the lake.

The Central Vancouver Island Health Unit has posted advisory notices at Art Mann Park Beach on several occasions since 1986 (Table 2), warning of the potential for increased risk to bathers' health. These notices were posted when the geometric mean exceeded 200 fecal coliforms/100 mL over a 30-day period. Fecal coliform values increased between 1973 and 1995.

There are 24 active domestic water licenses on Quamichan Lake. The Ministry of Health recommends that all surface waters in the province must undergo some form of treatment (e.g., disinfection, filtration) before being used as a drinking source. Fecal coliform values must not exceed the 90th percentile criterion for partially treated drinking water of 100 MPN/100 mL, and 10 MPN/100 mL for disinfected drinking water. There are insufficient data to assess the suitability of the lake to be used as a drinking water source.

True colour: 7 % (one value) of the true colour values from Quamichan Lake (Figure 10) exceeded the criteria (15 colour units) for drinking water and recreation. Total colour values were constant (5 colour units) between 1993 and 1995.

Total aluminum (Figure 11): 14 % of the values exceeded the 30-day average criterion (0.05 mg/L) for protecting aquatic life. One value exceeded the maximum criterion for protecting drinking water (0.2 mg/L). This value occurred on May 14, 1992 when the values for several water quality indicators were high. All aluminum values were below the minimum detectable limit (0.06 mg/L) between March, 1993 and 1995. Analysis of samples from Quamichan Lake for aluminum should use a minimum detectable limit 10 times lower than the lowest criterion (e.g., 0.005 mg/L). This would provide more accurate data for comparison to the 30-day average criterion (0.05 mg/L) for protecting aquatic life.

Total copper (Figure 12) 21% of the values exceeded the 30-day average criteria (0.002 mg/L) for protecting aquatic life in water with hardness less than or equal to 50 mg/L of CaCO3. All copper values reported in 1994 and 1995 were at the minimum detectable limit of 0.002 mg/L. Analysis of samples from Quamichan Lake for copper should use a minimum detectable limit 10 times lower than the lowest criterion (e.g., 0.0002 mg/L). This would provide more accurate data for comparison to the 30-day average criterion (0.002 mg/L) for protecting aquatic life.

Total iron (Figure 13): One value (0.451 mg/L), on May 14, 1992, exceeded the maximum criterion (0.3 mg/L) for protecting aquatic life, and drinking water.

Total manganese (Figure 14): 21% of the values exceeded the criterion (0.05 mg/L) for protecting drinking water. One value (0.133 mg/L), on May 14, 1992, exceeded the criterion for protecting aquatic life. Total manganese values did not been exceeded the criteria after 1992.

Total residue (i.e., dissolved plus suspended solids) ranged from 86 mg/L to 212 mg/L (Figure 15). The criterion for suspended solids could not be used because there were insufficient suspended solids (non-filterable residues) data. There are no criteria for total residues. Specific conductivity (µS/cm) can be used to indicate dissolved solid concentrations. These values (Figure 16) were below all criteria for specific conductivity.

Dissolved silica (Figure 17): These values indicate that dissolved silica was a not limiting factor (i.e., values were greater than 0.5 mg/L) for diatom growth in Quamichan Lake in 1994 (Wetzel, 1975).

Total zinc (Figure 18): 2 of 14 values exceeded the criterion for protecting phytoplankton (0.014 mg/L). Analysis of samples from Quamichan Lake for zinc should use a minimum detectable limit 10 times lower than the lowest criterion (e.g., 0.001 mg/L). This would provide more accurate data for comparison to the criterion (0.014 mg/L) for protecting phytoplankton.

pH (Figure 19) values ranged between 7.1 and 7.4 and met all criteria. The values were relatively constant between 1988 and 1995.


Conclusions - State of Water Quality


Recommendations for Water Quality Management

Remediation

We recommend that a remediation plan be developed and implemented to improve water quality in Quamichan Lake.

Monitoring

We recommend that minimum detectable limits for analytical procedures used to measure total aluminum, total copper, and total zinc in Quamichan Lake water must be at least 10 times lower than the criterion level. Monitoring for these water quality indicators and total manganese should be done in conjunction with the spring overturn and mid-summer sampling program.

We recommend that sampling at the surface and at depth during spring overturn and mid-summer be conducted at SEAM site E207465. The focus of this monitoring will be to identify changes in water quality attributed to activities within the watershed such as urbanization, changes in nonpoint discharge, changes in biological activity in the lake. This monitoring program would include the following water quality indicators:

This monitoring program could be implemented by a Quamichan Lake stewardship group with assistance from the Ministry of Environment, Lands and Parks.

We recommend that fecal coliform sampling continue at Art Mann Park beach on Quamichan Lake. The monitoring program is being implemented by the Central Vancouver Island Health Unit. In future, local interest groups (e.g., Quamichan Lake stewardship group, North Cowichan Valley Regional District) could assist with this ongoing monitoring.

We recommend that fecal coliform sampling be started at the intakes of all domestic licences used for drinking water on Quamichan Lake. The monitoring program would require that 5 samples be collected in 30 days at the intakes of these domestic licences. The fecal coliform values from these samples would be compared to the drinking water criteria. The monitoring program could be implemented by the Central Vancouver Island Health Unit, or by a Quamichan Lake stewardship group.


Figure 3 Total phosphorus (average in the water column before stratification) from Quamichan Lake


Figure 4 Total phosphorus from Quamichan Lake


Figure 5 Total dissolved phosphorus from Quamichan Lake


Figure 6 Dissolved ammonia from Quamichan Lake


Figure 7 Kjeldahl nitrogen from Quamichan Lake


Figure 8 N:P Ratio from Quamichan Lake


Figure 9 Total calcium from Quamichan Lake


Figure 10 True colour from Quamichan Lake


Figure 11 Total aluminum from Quamichan Lake


Figure 12 Total copper from Quamichan Lake


Figure 13 Total iron from Quamichan Lake


Figure 14 Total manganese from Quamichan Lake


Figure 15 Total residues from Quamichan Lake


Figure 16 Specific conductivity from Quamichan Lake


Figure 17 Dissolved silica from Quamichan Lake


Figure 18 Total zinc from Quamichan Lake


Figure 19 pH from Quamichan Lake


Table 1 Summary of water quality data from Quamichan Lake (SEAM site E207465)

Water Quality
Indicator

Average

Std Dev

Number of
samples

Maximum

Minimum

SPRING OVERTURN MONITORING

.

.

.

.

.

Water Clarity and Colour

.

.

.

.

.

Colour, true (TCU)

7.9

4.3

14

20

5

Colour, total absorbance (TAC)

8.4

2.1

8

12

6

Residues, non-filterable (mg/L)

4.5

0.71

2

5

4

Extinction depth (m)

.

.

1

2.4

2.4

General Ions

.

.

.

.

.

pH (pH units)

7.26

0. 11

9

7.4

7.1

Residues, filterable (mg/L)

101

1.4

2

102

100

Residues, total (mg/L)

117.5

42.5

12

212

86

Specific conductivity (µS/cm)

144.8

5.4

17

152

138

Calcium, total (mg/L)

14.03

0.7

14

15.3

13

Magnesium, total (mg/L)

3.917

0.269

14

4.404

3.6

Silica, dissolved (mg/L)

1.81

0.98

14

3.3

L 0.5

Sulphate, dissolved (mg/L)

17.25

2.24

6

19.1

14.3

Temperature, water (° C)

11

0

3

11

11

Nutrients

.

.

.

.

.

Nitrogen, total (mg/L)

0.385

0.021

2

0.4

0.37

Nitrogen, ammonia (mg/L)

0.0119

0.0112

15

0.048

L 0.005

Nitrogen, Kjeldahl (mg/L)

0.538

0.475

17

2.35

0.32

Nitrogen, Nitrate+Nitrite (mg/L)

0.0206

0.002

17

0.03

L 0.02

Nitrogen, Nitrate (mg/L)

.

.

2

0.02

L 0.02

Nitrogen, Nitrite (mg/L)

.

.

4

0.006

L 0.005

Phosphorus, total (mg/L)

0.017

0.0076

17

0.031

0.005

Phosphorus, ortho (mg/L)

.

.

3

0.01

L 0.003

Phosphorus, total dissolved (mg/L)

0.02

0.044

17

0.191

L 0.003

Oxygen, dissolved (mg/L)

9.27

0.12

3

9.4

9.2

Metals

.

.

.

.

.

Aluminum, total (mg/L)

0.06

0.046

14

0.21

L 0.02

Boron, total (mg/L)

0.043

0.021

14

0.092

0.008

Barium, total (mg/L)

0.008

0.0008

14

0.01

0.007

Chromium, total (mg/L)

L 0.002

0

14

0.003

L 0.002

Copper, total (mg/L)

0.002

0.001

14

0.006

L 0.001

Iron, total (mg/L)

0.088

0.107

14

0.451

0.019

Manganese, total (mg/L)

0.04

0.041

14

0.133

0.007

Potassium, total (mg/L)

1.217

0.133

6

1.3

1

Sodium, total (mg/L)

7.232

0.641

6

8.05

6.43

Sodium, dissolved (mg/L)

7.64

0.521

10

8.5

7.2

Silicon, total (mg/L)

1.004

0.427

14

1.74

0.53

Strontium, total (mg/L)

0.097

0.005

14

0.106

0.09

Sulfur, total (mg/L)

4.973

0. 219

6

5.18

4.68

Zinc, total (mg/L)

0.01

0.005

14

0.02

0.003

Note: L = less than


Table 2 Summary of Central Vancouver Island Health Unit's Bacteriological data (fecal coliform/100 mL) from Quamichan Lake (Art Mann Park)

Year

1973

1974

1975

1976

1977

1978

1979

1980

1981

1982

1983

1984

Maximum

L 3

4

L 3

240

240

240

4

43

240

2400

460

460

Minimum

L 3

L 3

L 3

L 3

L 3

L 3

L 3

L 3

L 3

23

L 3

L 3

Geometric Mean

L 3

28

.

7.98

11.73

6.43

3.3

9.67

19.89

216.23

18.86

20.66

Number of Samples

4

19

1

10

6

6

3

6

9

8

11

11


Year

1985

1986

1987

1988

1989

1990

1991

1994

1995

Maximum

240

G 2400

2400

G 2400

6700

3250

785

G 6400

G 6400

Minimum

4

L 3

4

93

80

500

35

225

25

Geometric Mean

25.54

70.06

177

887.34

931.94

1377.56

162.55

13697.0

1454.19

Number of Samples

11

13

12

12

8

9

3

5

4


References

Klein, R.J. and R. Heathman (1972). A Reconnaissance Survey of Quamichan Lake. Ministry of Environment. Fisheries Branch. Victoria, B.C.

Nagpal, N.K., L.W. Pommen, and L.G. Swain (1995). Approved and Working Criteria for Water Quality. Ministry of Environment, Lands and Parks, Environmental Protection Department, Water Quality Branch, Victoria, B.C.

Personal Communication Gary Smith (1995). Central Vancouver Island Health Unit, Duncan, B.C.

Personal Communication Barry Boettger (1995). Ministry of Health. Victoria, B.C.

Wetzel, R.G. (1975) Limnology. Philadelphia, W.B. Saunders Co. 743p.

Willis, Cunliffe, Tait & Co. (1979) Drainage Feasibility Study Quamichan Lake Preliminary Report and Benefit-Cost Assessment. A Report for the Ministry of Environment, Water Investigations Branch. Victoria, B.C.

Yaworski, B.A. (1986). Small Lake Enhancement Feasibility Study. Vancouver Island M.U. 1-4. Fisheries Improvement Unit, Ministry of Environment, Lands and Parks, Fisheries Branch, Victoria, B.C.


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