2.0 Eagle Lake Catchment: Water Quality Conditions

Surface water quality conditions in the Eagle 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. 

 

The water quality ratings scored high across this catchment and ranges from "Fair to Very Good" (Table 1).  All ratings were determined by the Canadian Council of Ministers of the Environment (CCME) Water Quality Index.

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. “Very Good" indicates water quality is protected with a virtual absence of threat or impairment; conditions are very close to natural or pristine 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.

2.1 Leggat Lake Water Quality

Surface water quality conditions in Leggat Lake have been monitored by RVCA’s Watershed Watch Program since 2006. Data from the deep point site (DP1) have been used to calculate the WQI rating for Leggat Lake, which averaged “Fair-Good” over the 2006-2017 period (Table 1). Low-moderate nutrient concentrations, generally good oxygen availability and clear water all influenced this rating. 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. Leggat 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. Concentrations below 0.010 mg/l are generally considered to be minimal and unlikely to have problems associated with nutrient loading.

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 Leggat 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 though average annual concentrations were fairly consistent (Figure 3 and 4); no significant trend^[2] was observed in the 2006-2017 data set. Ninety percent of samples analyzed for TP were less than the TP guideline and the average concentration was 0.012 mg/l (Table 3).  TKN concentration also showed variability,  as with TP concentrations no significant change was observed (Figures 5 and 6). Ninety-five percent of reported results were below the TKN guideline and the average TKN concentration was 0.342 mg/l (Table 3).

Overall, the data presented indicates that nutrient concentration may be considered low with few exceedances in the mid-lake, deep water site on Leggat Lake.

Nutrients around Leggat 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, B and E were monitored yearly; while sites C, D, F, G and H were only sampled in 2009 and 2014.

Average total phosphorous concentrations are below the TP guideline at all of sites, with the exception of site B in 2012 and 2014 (Figure 7). All subsequent results are well below the guideline at this site, and concentrations do not appear to be indicative of persistent problem. Average TKN concentrations were below the guideline at all sites (Figure 8).

Summary of Leggat Lake Nutrients

Leggat Lake nutrient concentrations are general below the guidelines, with few exceedances. 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-such as site B.

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 Leggat 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 5.5 m and shows that all 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 no individual reading has been below the guideline and measured depths range from 3.0 m to 9 m. A declining trend was observed in Secchi depths over the 2006-2017 data set, meaning that clairity in the water column has been reduced through this period.

 

Summary of Leggat Lake Water Quality

Waters in Leggat Lake are generally 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 Leggat Lake Fish Habitat

Two other factors, dissolved oxygen/temperature and pH were also assessed to provide an overall sense of the health of Leggat Lake from a fish habitat perspective.

2.1.3.1 Leggat 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 10 m of the water column. Periods of very limited conditions were observed in the summer of 2013 and 2015, 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 Leggat 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).  Surface water’s that are found to be more alkaline (higher pH) are common in many regions of the Tay River subwatershed and can generally be attributed to the geology rather than anthropogenic activities. Biological activities such as increased photosynthesis from algal blooms and plant growth may also influence pH.

 

Summary of Water Quality for Fish Habitat In Leggat Lake

Overall the water chemistry data at the deep point describes suitable habitat conditions for fish species such as bass, walleye and pike. 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 Leggat 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 98 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.

 

Summary of Leggat Lake Bacterial Contamination

The results presented above indicate that bacterial contamination is not a significant concern in Leggat Lake and the water should be safe for recreational use such as swimming and boating.The results presented above provide evidence that bacterial contamination is not a significant concern in Leggat Lake and the water should be safe for recreational use such as swimming and boating.

2.2 Eagle Lake Water Quality

Surface water quality conditions in Eagle Lake have been monitored by RVCA’s Watershed Watch Program since 2002. Data from the deep point site (DP1) have been used to calculate the WQI rating for Eagle Lake, which averaged “Very Good” over the 2006-2017 period (Table 1). Low nutrient concentrations, good oxygen availability and clear water all influenced this rating. 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-K) please see Figure 2.  

2.2.1 Eagle 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. Concentrations below 0.010 mg/l are generally considered to be minimal and unlikely to have problems associated with nutrient loading.

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 Eagle Lake Deep Point

TP and TKN sampling results collected by the RVCA are presented in Figures 13 to 16. Some variability has occurred in the sampled TP concentrations at this site though average annual concentrations were fairly consistent (Figure 13 and 14); no significant trend^[2] was observed in the 2006-2017 data set. Ninety-eight percent of samples analyzed for TP were less than the TP guideline and the average concentration was 0.008 mg/l (Table 7).  TKN concentration also showed variability, as with TP concentrations no significant change was observed (Figures 15 and 16). All reported results were below the TKN guideline and the average TKN concentration was 0.297 mg/l (Table 7).

Overall, the data presented indicates that nutrient concentration may be considered low with few exceedances in the mid-lake, deep water site on Eagle Lake.

 

Nutrients around Eagle Lake

The average nutrient concentrations at monitored shoreline sites around the lake vary from year to year (Figures 17 and 18). Please note that in the 2006-2017 monitoring period sites A, B, F and G were monitored yearly; while sites C, D, E, G, H , I and K were only sampled in 2007, 2012 and 2017.

Average total phosphorous concentrations are below the TP guideline at all of sites (Figure 17), and concentrations do not appear to be indicative of a persistent problem. Average TKN concentrations were below the guideline at all sites, with the exception of elevated instances at site F in 2006 and site B in 2008. In both cases neither site has had sustained periods of elevated concentrations (Figure 18).

Summary of Eagle Lake Nutrients

Eagle Lake nutrient concentrations are general below the guidelines, with few exceedances. 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.

2.2.2 Eagle Lake Water Clarity

Water clarity is measured using a Secchi disk during each deep point sample. Table 8 summarizes the recorded depths with an average depth of 5.0 m and shows that all 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 19 shows that no individual reading has been below the guideline and measured depths range from 3.5 m to 9.5 m. No trend was observed in Secchi depths over the 2006-2017 data set.

Summary of Eagle Lake Water Clarity

Waters in Eagle Lake are generally 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).

2.2.3 Eagle Lake Fish Habitat

Two other factors, dissolved oxygen/temperature and pH were also assessed to provide an overall sense of the health of Eagle Lake from a fish habitat perspective.

2.2.3.1 Eagle Lake Dissolved Oxygen and Temperature

Warm-water Fish Community

The red bars in Figure 20 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 throughout the water column in the spring and early summer, declining to about 15 m by late summer.  Overall, no significant change was noted in conditions through the 2006-2017 period.

Cold-water Fish Community

Optimal habitat for adult Lake Trout has a dissolved oxygen concentration of 6 mg/l, although concentrations as low as 4 mg/l, can be tolerated.  However, juvenile Lake Trout have a higher minimum dissolved oxygen requirement of 7 mg/l. Data taken at the deep point site on Eagle Lake from May to late July/early August indicate adequate habitat for both adult and juvenile Lake Trout. For the interval from August 14 to September 30, of the 34 dissolved oxygen/temperature profiles available from 2002 to 2015 at Eagle Lake, 11 are from this time span.

As shown in Figure 21, for each year with data available, the light blue zone represents the portion of the usable lake depth as lake trout habitat, the light red zone as optimal habitat with up to 7 mg/litre of dissolved oxygen. Usable habitat for lake trout is defined as less than 15.5°C and 4 mg/l or more of dissolved oxygen. Optimal habitat is defined as less than 10°C and 7 mg/l or more of dissolved oxygen.

This data suggests that Lake Trout habitat is inadequate to borderline in some years, e.g., 2002, 2006, and 2009 to 2011. In other years, e.g., 2003, 2007, 2012, 2014 and 2015, habitat conditions in the late summer are acceptable for Lake Trout. Based on such dissolved oxygen/temperature profiles, it seems that every 4 to 5 years there is sufficient dissolved oxygen, i.e., a minimum of 7 mg/l, in portions of the water column to support juvenile Lake Trout.

These findings suggest that it is the late summer dissolved oxygen/temperature profiles that may be a limiting factor affecting the adequacy of the lake environment for Lake Trout, particularly juvenile fish. Nonetheless, there is potential for survival of a proportion of juvenile fish in certain years, so that some degree of recruitment for the adult pool of Lake Trout at Eagle Lake seems probable.

2.2.3.2 Eagle Lake pH

The majority of samples (Figure 22) 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 9).  Surface water’s that are found to be more alkaline (higher pH) are common in many regions of the Tay River subwatershed and can generally be attributed to the geology rather than anthropogenic activities. Biological activities such as increased photosynthesis from algal blooms and plant growth may also influence pH.

 

Summary of Water Quality for Fish Habitat in Eagle Lake

Overall the water chemistry data at the deep point describes suitable habitat conditions for fish species such as bass, walleye and pike. pH conditions are within the range recommended for the protection of aquatic life. Overall, the data indicates a healthy environment for aquatic species.

2.2.4 Eagle 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 10.

Throughout the 2006-2017 period, 100 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 3 CFU/100ml (Table 10). This provides support that there is little indication of bacterial contamination around the lake. Figure 23 show the distribution of counts across all shoreline sites. All sites fall well below the guideline of 100 CFU/100ml.

 

Summary of Bacterial Contamination

The results presented above indicate that bacterial contamination is not a significant concern in Eagle Lake and the water should be safe for recreational use such as swimming and boating.

2.3 Eagle Creek Water Quality

There is one stream site on Eagle Creek monitored in the Eagle Lake-Eagle Creek catchment (EAG-01, Figure 2).  Analysis of the data has considered over the 2006-2017 period. Water quality at this site is reported as “Fair-Good” (Table 1) as determined by the Canadian Council of Ministers of the Environment Water Quality Index (CCME WQI). The score at this due to the majority of monitored parameters having results below established guidelines. For more information on the CCME WQI, please see the Tay River Subwatershed Report.  Only those parameters with exceedances that influenced the rating will be discussed in the following.

2.3.1 Eagle 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] at the monitored site.

Tables 11 and 12 summarize average nutrient concentrations at the monitored site on Eagle Creek and show the proportion of results that meet the guidelines.

 

The majority of TP results (72 percent) were below the guideline with an average concentration of 0.027 mg/l (Table 11).  Concentrations tend to increase over the summer (Figure 24). Elevated counts were observed during the 2008 and 2016 sampling periods, this may be due to significant periods of wet weather during these sampling years (Figure 25).  Please note that no samples were collected over the winter months. Overall, there was no significant trend in the monitoring data throughout the 2006-2017 period (Figure 25).    

 

TKN results show that the bulk of results exceeded the guideline (Figure 26); 46 percent of samples were below the guideline and the average concentration was slightly elevated at 0.575 mg/l (Table 12). As with TP results, TKN concentrations appear to increase throughout the summer months (Figure 26).  Periods of elevated concentrations were observed in 2008, 2011 and 2016 (Figure 27).  Overall there was no significant trend in the monitoring data throughout the 2006-2017 period.

Summary of Eagle Creek Nutrients

The data shows that periods of elevated nutrients occur occasionally in Eagle Creek, particularly in regards in TKN. Elevated nitrogen is likely due to the influence of surrounding wetland areas, wetlands are naturally rich in nitrogen and appear to be contributing to the concentrations in this creek.  Though this is likely to be a natural condition it is important to reduce human impacts wherever possible. Strategies to reduce nutrient inputs may include diversion of runoff to the creek from surrounding developed areas (i.e. roadways) and enhanced shoreline buffers.

2.3.2 Eagle Creek E. 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 milliliters (CFU/100 ml) is used to assess E. coli. Counts greater than this guideline indicate that bacterial contamination may be a problem within a waterbody.

Table 13 summarizes the geometric mean for the monitored site on Eagle Creek and shows the proportion of samples that meet the E. coli guideline of 100 CFU/100 ml. The monthly geometric mean with respect to the guideline for the 2006-2017 period is shown in Figure 28 and distribution of sampled counts is shown in Figure 29.

 

E. coli results at site EAG-01 indicate bacterial counts are typically below (79 percent) the E. coli guideline, similarly the count at geometric mean is 42 CFU/100ml (Table 13) and well below the guideline.  E. coli counts are slightly higher during the summer months as warmer temperatures are needed for bacteria to survive (Figure 28). Results have varied for each sampled year, but no trend was observed across the 2006-2017 period (Figure 29).

Summary of  Eagle Creek Bacterial Contamination

Results indicate that bacterial contamination is not a concern in Eagle Creek. The count at the geometric mean is below the guideline and a limited number of counts exceeding the guideline have been observed. The elevated samples that do occur are most likely due to wildlife and can be considered natural variability in the aquatic ecosystem.  However good stewardships practices should be maintained throughout the drainage area to protect both Eagle Creek and Bobs Lake downstream; this includes properly maintaining septic systems, enhancing shoreline buffers and restricting livestock access-all actions that can help to protect water quality conditions in Eagle Creek.

2.3.3 Eagle Creek Metals

Of the metals routinely monitored in Eagle Creek, aluminum (Al)  and iron (Fe) reported concentrations above their respective PWQOs. In elevated concentrations, these metals can have toxic effects on sensitive aquatic species.  The PWQO for Al is 0.075 mg/l and Fe is 0.300 mg/l.

Tables 14 and 15 summarize metal concentrations at the monitored site, as well as show the proportion of samples that meet guidelines. Figures 30 and 32 show the monthly average concentrations with respect to the guidelines; Figures 31 and 33 show the distribution of sample results.

 

Results show that Al concentrations often meet the objective with 79 percent of samples below the guideline, no significant trend was observed in the sampled concentrations (Figure 31). The average concentration of Al was below the guideline at 0.044 mg/l (Table 14).

The majority of Fe results were below the guideline; 68 percent of samples were below the guideline in the 2006-2017 period (Figure 33), as with Al results no trend was observed. The average concentration was below the guideline in the  reporting period with a concentration of 0.249 mg/l (Table 15).

Summary of Eagle Creek Metals

Concentrations of both iron and aluminum have not shown any significant change within Eagle Creek, though exceedances have occurred the majority of samples as well as average concentration are below respective guidelines.  Efforts should continue to be made to identify if any significant pollution sources do exist and implement best management practices reduce any inputs such as storm water runoff, metal alloys, fungicides and pesticides to improve overall stream health and lessen downstream impacts.

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