2.0 Elbow Lake Catchment: Water Quality Conditions
Surface water quality conditions in the Elbow Lake catchment are monitored by the Rideau Valley Conservation Authority’s (RVCA) Watershed Watch Program and Baseline Water Quality Monitoring Program. Watershed Watch monitors watershed lakes to assess nutrient concentrations, water clarity, dissolved oxygen availability and pH. The baseline water quality program focuses on streams; data is collected for 22 parameters including nutrients (total phosphorus, total Kjeldahl nitrogen and ammonia), E. coli, metals (like aluminum and copper) and additional chemical/physical parameters (such as alkalinity, chlorides, pH and total suspended solids). Figure 2 shows the locations of monitoring sites in the catchment. Figure 2 shows the locations of monitoring sites in the catchment.
Water Quality Rating in the Elbow Lake Catchment
Water quality ratings for Tay River Subwatershed lakes, the Tay River and streams are made up of many water quality parameters blended together to allow water quality to be represented across a range of categories from Very Poor, to Poor, Fair, Good and Very Good. This is based on the Canadian Council of Ministers of the Environment Water Quality Index (CCME WQI) and guidelines for the protection of aquatic life; it does not reflect the suitability of water quality conditions for recreational uses such as swimming or other water sports.
The water quality ratings across this catchment ranges from "Very Poor to Good" (Table 1). A “Very Poor” rating indicates that water quality is almost always threatened or impaired; conditions usually depart from natural or desirable levels. A “Poor” rating indicates that water quality is frequently threatened or impaired; conditions often depart from natural or desirable levels. A "Fair" rating indicates that water quality is usually protected but is occasionally threatened or impaired; conditions sometimes depart from natural or desirable levels. A rating of "Good" indicates that only a minor degree of threat or impairment is observed and conditions rarely depart from natural or desirable levels. Each parameter is evaluated against established guidelines to determine water quality conditions. Those parameters that frequently exceed guidelines are presented below. Data has been analyzed over the 2006-2017 period for general trends and conditions. Table 1 shows the overall rating for the monitored surface water quality sites within the catchment and Table 2 outlines the Water Quality Index (WQI) scores and their corresponding ratings.
| Site | Location | 2006-2008 | 2009-2011 | 2012-2014 | 2015-2017 |
|---|---|---|---|---|---|
| DP1 | Elbow Lake | Poor (47) | Poor (53) | Poor (53) | Very Poor (34) |
| FIS-03 | Fish Creek at Long Lake Rd | Good (83) | Fair (67) | Fair (78) | Fair (69) |
| FIS-A | Fish Creek upstream of Bobs Lake | Poor (58) | Fair (76) | Good (86) | Good (81) |
| Rating | Index Score |
|---|---|
| Very Good (Excellent) | 95-100 |
| Good | 80-94 |
| Fair | 65-79 |
| Poor (Marginal) | 45-64 |
| Very Poor (Poor) | 0-44 |
2.1 Elbow Lake Water Quality
Surface water quality conditions in Elbow Lake have been monitored by RVCA’s Watershed Watch Program since 2004. Data from the deep point site (DP1) have been used to calculate the WQI rating for Elbow Lake, which averaged “Very Poor-Poor” over the 2006-2017 period (Table 1). Moderate nutrient concentrations and periods of limited oxygen availability influenced this rating. While the WQI is a useful tool in summarizing and comparing water quality conditions across a range of sites, it does not highlight the unique conditions of individual waterbodies. Elbow lake is one of a few smaller lakes in the upper watershed that are fed by nutrient rich wetlands and are shallow in depth. As a result, some of these smaller lakes, including Elbow, received a lower water quality rating due to naturally occurring elevated nutrient levels. It should also be noted that bacterial counts for Elbow Lake, which are not used in calculating the WQI rating, were very low and do not provide any indication of impairment for recreational use. The following discussion explains how each of the monitored water quality parameters contributes to the lake’s water quality.
This report also considers data from eight additional shoreline sites that are monitored around the lake. These sites have not been included in the calculation of the CCME WQI rating, as they are not monitored with the same frequency as the deep point site. However, they do provide important information on water quality conditions in the near shore areas. For locations of shoreline sites (A-H) please see Figure 2.
2.1.1 Elbow Lake Nutrients
Total phosphorus (TP) is used as a primary indicator of excessive nutrient loading and contributes to abundant aquatic vegetation growth and depleted dissolved oxygen levels. The Provincial Water Quality Objective (PWQO) is used as the TP Guideline and states that in lakes, concentrations greater than 0.020 mg/l indicate an excessive amount of TP within the water column.
Total Kjeldahl nitrogen (TKN) is used as a secondary indicator of nutrient loading. RVCA uses a guideline of 0.500 mg/l to assess TKN[1] within surface waters.
Nutrients at the Elbow Lake Deep Point
TP and TKN sampling results collected by the RVCA are presented in Figures 3 to 6. Some variability has occurred in the sampled TP concentrations at this site (Figure 3 and 4); no significant trend[2] was observed in the 2006-2017 data set. Eighty-four percent of samples analyzed for TP were less than the TP guideline and the average concentration was 0.015 mg/l (Table 3). TKN concentration also showed variability, as with TP concentrations no significant change was observed (Figures 5 and 6). Seventy three percent of reported results were below the TKN guideline and the average TKN concentration was 0.453 mg/l (Table 3).
| Total Phosphorous 2006-2017 | |||
|---|---|---|---|
| Site | Average (mg/l) | Below Guideline | No. Samples |
| DP1 | 0.015 | 84% | 45 |
| Total Kjeldahl Nitrogen 2006-2017 | |||
| Site | Average (mg/l) | Below Guideline | No. Samples |
| DP1 | 0.453 | 73% | 45 |
Overall, the data presented indicates that nutrient concentration may be considered moderate with occasional exceedances in the mid-lake, deep water site on Elbow Lake.
Nutrients around Elbow Lake
The average nutrient concentrations at monitored shoreline sites around the lake vary from year to year (Figures 7 and 8). Please note that in the 2006-2017 monitoring period sites A, D, G and H monitored yearly; while sites B, C, E, and F were only sampled in 2009 and 2014.
Average total phosphorous concentrations are below the TP guideline during most year, with the exception of site C, site D in 2011 and 2017, and site H in 2011 and 2012. A single exceedance is also observed at site B in 2011 (Figure 7). Exceedances at sites that are monitored yearly (B, D, and H) are not consistent making it inconclusive if this is indicative of a persistent problem.
A similar pattern of occasional exceedances at some sites, particularly D and G was also observed in the TKN data set, however the majority of sites did report average concentrations below the guideline each year (Figure 8). Elevated results were also observed at all site in 2014, this may be due to an external factor such as weather conditions that influenced the lake at the time of sampling.
Summary of Elbow Lake Nutrients
Elbow Lake nutrient concentrations are generally below the guidelines. It is possible that occasional problems with nutrient enrichment (i.e. algal blooms or excessive plant growth) may be observed in some shallow, sheltered bays.
Efforts such as the diversion of runoff and enhanced shoreline buffers are important to continue to protect and enhance water quality, and reduce future nutrient increases-particularly in developed areas. Nutrient exceedances may be partially attributed to the natural aging of a lake and basin characteristics. All residents can help minimize their impact on the lake by reducing nutrient inputs through practices such as proper maintenance of septic systems, keeping shorelines natural and using phosphate free soaps and detergents. Promotion of sound stewardship and protection around lake is important to maintain and protect water quality conditions into the future.
2.1.2 Elbow Lake Water Clarity
Water clarity is measured using a Secchi disk during each deep point sample. Table 4 summarizes the recorded depths with an average depth of 3.0 m and shows that 77 percent readings have exceeded the minimum PWQO of 2 m; indicating that algae in the water column is not at excessive levels (good water clarity). Less than 2 m will indicate overproduction in a lake or significant inputs to the water column that are limiting light availability. Figure 9 shows that measured depths range from 1.3 m to 4.6 m. No significant trend was observed in Secchi depths over the 2006-2017 data set, meaning that clarity in the water column has not changed through this period.
| Secchi 2006-2017 | |||
|---|---|---|---|
| Site | Average (m) | Above Guideline | No. Samples |
| DP1 | 3.0 | 77% | 43 |
Summary of Elbow Lake Water Clarity
Waters in Elbow Lake are usually clear and sufficient sunlight is able to penetrate the water column to support aquatic life and provide sufficient visibility for safe recreational use (boating, swimming).
2.1.3 Elbow Lake Fish Habitat
Two other factors, dissolved oxygen/temperature and pH were also assessed to provide an overall sense of the health of Elbow Lake from a fish habitat perspective.
2.1.3.1 Elbow Lake Dissolved Oxygen and Temperature
The red bars in Figure 10 show the depths where suitable conditions exist for warm water fish species (temperature less than 25°C and dissolved oxygen greater than 4 mg/l) at the deep point site. The vertical axis represents the total lake depth at each site where the profile is taken. Suitable conditions typically were observed over the monitoring periods to about 6 m of the water column. Periods of very limited conditions were observed in the summer of 2011, 2012 and 2016, due to very warm water temperatures in the upper portion of the water column and depleted oxygen conditions at the deeper depths. Overall, no significant change was noted in conditions through the 2006-2017 period.
2.1.3.2 Elbow Lake pH
The majority of samples (Figure 11) were within guidelines established by the Canadian Council of Minister's of the Environment which state that pH should be between 6.5 and 9 to protect aquatic life (Table 5). Biological activities such as increased photosynthesis from algal blooms and plant growth may influence pH in addition to anthropogenic activities.
| pH 2006-2017 | |||
|---|---|---|---|
| Site | Average (mg/l) | Within Guideline | No. Samples |
| DP1 | 7.6 | 95% | 41 |
Summary of Water Quality for Fish Habitat in Elbow Lake
Overall the water chemistry data at the deep point describes suitable habitat conditions for warm water fish species. pH conditions are within the range recommended for the protection of aquatic life. Overall, the data indicates a healthy environment for aquatic species.
2.1.4 Elbow Lake E. Coli
E. coli is sampled at monitored shoreline sites twice each sampling season. E. coli data was not used in the calculations of the WQI rating for the lake due to differences in sampling frequency and site locations. E. coli data has been summarized in Table 6.
Throughout the 2006-2017 period 99 percent of samples collected by RVCA were below the E. coli guideline of 100 colony forming units (CFU) per 100 ml set by the PWQO; across the lake the count at the geometric mean was 4 CFU/100ml (Table 6). This provides support that there is little indication of bacterial contamination around the lake. Figure 12 show the distribution of counts across all shoreline sites. All sites fell well below the guideline of 100 CFU/100ml.
| E. coli 2006-2017 | |||
|---|---|---|---|
| Site | Geometric Mean (CFU/100ml) | Below Guideline | No. Samples |
| DP1 | 4 | 99% | 122 |
Summary of Elbow Lake Bacterial Contamination
The results presented above indicate that bacterial contamination is not a significant concern in Elbow Lake and the water should be safe for recreational use such as swimming and boating.
2.2 Fish Creek Water Quality
There are two stream sites on Fish Creek (FIS-03 and FIS-A) monitored in the Elbow Lake and Fish Creek catchment (Figure 1). Water quality at these sites ranged from "Poor" to “Good” (Table 1). The score at each site is largely influenced by elevated nutrient concentrations, iron and high bacterial counts. For more information on the CCME WQI, please see the Tay River Subwatershed Report 2017.
2.2.1 Fish Creek Nutrients
Total phosphorus (TP) is used as a primary indicator of excessive nutrient loading and may contribute to abundant aquatic vegetation growth and depleted dissolved oxygen levels. The Provincial Water Quality Objective (PWQO) is used as the TP Guideline and states that in streams concentrations greater than 0.030 mg/l indicate an excessive amount of TP.
Total Kjeldahl nitrogen (TKN) is used as a secondary indicator of nutrient loading. RVCA uses a guideline of 0.500 mg/l to assess TKN[1].
Tables 7 and 8 summarize average nutrient concentrations at the monitored sites within the Fish Creek catchment and show the proportion of results that met the guidelines.
| Total Phosphorous 2006-2017 | |||
|---|---|---|---|
| Site | Average (mg/l) | Below Guideline | No. Samples |
| FIS-03 | 0.063 | 59% | 76 |
| FIS-A | 0.037 | 58% | 64 |
| Total Kjeldahl Nitrogen 2006-2017 | |||
|---|---|---|---|
| Site | Average (mg/l) | Below Guideline | No. Samples |
| FIS-03 | 0.808 | 33% | 76 |
| FIS-A | 0.678 | 8% | 64 |
2.2.1.1 Fish Creek Monitoring Site FIS-03
Elevated TP results occurred occasionally at site FIS-03 throughout the monitoring period; 59% of samples were below the guideline (Figure 14) though average concentrations generally exceed the guidelines during the summer months (Figure 13). The average TP concentration was above the guideline of 0.030 mg/l at 0.063 mg/l (Table 7).
The majority of TKN results have exceeded the guideline (Figure 16), 33 percent of samples below the guideline. The average concentration was 0.808 mg/l and exceeded the guideline of 0.500 mg/l (Table 8).
There was no significant change[2] in the sampled concentrations of TP or TKN at this site over the 2006-2017 period (Figure 14 and 16).
2.2.1.2 Fish Creek Monitoring Site FIS-A
Elevated TP results also occurred occasionally at the downstream site FIS-A throughout the monitoring period; 58% of samples were below the guideline (Figure 14) monthly average concentrations were variable across the monitoring period (Figure 13). The average TP concentration was just above the guideline at 0.037 mg/l (Table 7).
Nearly all TKN results have exceeded the guideline (Figure 16), only 8 percent of samples were below the guideline. Concentrations were fairly consistent with the highest concentrations observed in October (Figure 15). Overall the average concentration was 0.678 mg/l and exceeded the guideline of 0.500 mg/l (Table 8).
There was no significant change[2] in the sampled concentrations of TP or TKN at this site over the 2006-2017 period (Figure 14 and 16). It should also be noted that access to site FIS-A is difficult and has resulted in fewer collected samples compared to the upstream site FIS-03.
Summary of Fish Creek Nutrients
Results of the two monitored sites on Fish Creek shows that periods of nutrient enrichment is a feature of this creek. Both parameters (total phosphorus, total Kjeldahl nitrogen) have concentrations that exceed their respective guidelines. Elevated nutrients may result in nutrient loading downstream and to the Bobs Lake. High nutrient concentrations can help stimulate the growth of algae blooms and other aquatic vegetation in a water body and deplete oxygen levels as the vegetation dies off. It should be noted that this creek is fed by the extensive wetlands, this wetland complex is naturally nutrient rich and is likely the largest contributor to naturally elevated nutrient conditions. Development in this area is also minimal but best management practices such as minimizing storm water runoff, enhanced shoreline buffers, minimizing/discontinuing the use of fertilizers and restricting livestock access in both surrounding agricultural and developed areas can help to reduce additional nutrient enrichment both within this creek.
2.3 Fish Creek Escherichia coli
Escherichia coli (E. coli) is used as an indicator of bacterial pollution from human or animal waste; in elevated concentrations it can pose a risk to human health. The PWQO of 100 colony forming units/100 millilitres (CFU/100 ml) is used as a guideline. E. coli counts greater than this guideline indicate that bacterial contamination may be a problem within a waterbody.
Table 9 summarizes the geometric mean [3] for the monitored sites on Fish Creek and shows the proportion of samples that meet the E. coli guideline of 100 CFU/100 ml. The results of the geometric mean with respect to the guideline for the 2006-2017 period are shown in Figures 17 and 18.
| E. coli 2012-2017 | |||
|---|---|---|---|
| Site | Geometric Mean (CFU/100ml) | Below Guideline | No. Samples |
| FIS-03 | 60 | 59% | 76 |
| FIS-A | 65 | 66% | 64 |
2.3.1. Fish Creek Monitoring Site FIS-03
E. coli counts at site FIS-03 show that there has been no significant trend in bacterial counts (Figure 18). The count at the geometric mean was 60 (Table 9) and the majority of results (59 percent) were below the E. coli guideline. Figure 17 shows that periods of elevated counts are most common is September; this can likely be attributed to warm weather and low flow conditions.
2.3.2. Fish Creek Monitoring Site FIS-A
At site FIS-A, there was no significant trend noted with respect to E. coli counts (Figure 18). The count at the geometric mean was 65 (Table 9), and the majority of results (66 percent) were below the E. coli guideline. As with upstream site FIS-03, periods of elevated counts are most common in September (Figure 17).
Summary of Fish Creek Bacterial Contamination
Bacterial contamination does not appear to be a significant concern in Fish Creek, results are very comparable between upstream and downstream sites. As indicated by Figure 18, occasional exceedances above the guideline of 100 CFU/100ml have been observed. Best management practices such as enhancing shoreline buffers, limiting livestock access and minimizing runoff in both rural and developed areas can help to protect Fish Creek into the future.
2.4 Fish Creek Metals
Of the metals routinely monitored in Fish Creek, iron (Fe) occasionally reported concentrations above its respective Provincial Water Quality Objective of 0.300 mg/l. In elevated concentrations, this metal can have toxic effects on sensitive aquatic species.
Table 10 summarizes Fe concentrations within the creek as well as show the proportion of samples that meet guidelines. Figures 19 and 20 show Fe concentrations with respect to the guidelines for the monitoring period, 2006-2017.
| Iron 2006-2017 | |||
|---|---|---|---|
| Site | Average (mg/l) | Below Guideline | No. Samples |
| FIS-03 | 0.556 | 48% | 28 |
| FIS-A | 0.549 | 64% | 22 |
2.4.1 Fish Creek Monitoring Site FIS-03
The average Fe concentrations in site FIS-03 was 0.556 mg/l and exceeded the guideline (PWQO). Forty-eight percent of samples were below the guideline and there was no significant change in Fe concentrations across the monitoring period (Table 10, Figure 20). Monthly concentrations were highly variable across the monitoring period, and strongly influenced by single elevated samples (Figure 19).
2.4.2 Fish Creek Monitoring Site FIS-A
Iron concentrations at FIS-A were comparable to site FIS-03. The average Fe concentrations in site FIS-03 was 0.549 mg/l and 64 percent of samples were below the guideline. Overall there was no significant trend in Fe concentrations Figure 20). Monthly concentrations were also variable across the monitoring period (Figure 19).
Summary of Fish Creek Metals
In the Fish Creek there is little evidence of increased metal concentration above respective guidelines, though elevated concentrations do occur it is quite likely that they are naturally occurring from groundwater inputs. Even so continued efforts should be made to protect against possible pollution sources and implement best management practices to reduce any inputs such as storm water runoff from hardened surfaces to improve overall stream health and lessen downstream impacts.
2 The evaulations of temporal trends or significant change over time in the data set was preformed using the Mann Kendall trend test and Sens slope estimator, a confidence levels of p<0.05 was used to determine if trends were significant.
3 A type of mean or average, which indicates the central tendency or typical value of a set of numbers by using the product of their values (as opposed to the arithmetic mean which uses their sum). It is often used to summarize a variable that varies over several orders of magnitude, such as E. coli counts.