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Otter Creek

Full Catchment Report

OtterCreek124DS 2014

Middle Rideau Subwatershed Report 2015

OTTER LAKE AND CREEK CATCHMENT

The Rideau Valley Conservation Authority produces individual reports for ten catchments in the Middle Rideau subwatershed. Using data collected and analysed by the RVCA through its watershed monitoring and land cover classification programs, surface water quality conditions are reported for Otter Lake and Otter Creek along with a summary of environmental conditions for the surrounding countryside every six years.

This information is used to better understand the effects of human activity on our water resources, allows us to better track environmental change over time and helps focus watershed management actions where they are needed the most to help sustain the ecosystem services (cultural, aesthetic and recreational values; provisioning of food, fuel and clean water; regulation of erosion/natural hazard protection and water purification; supporting nutrient/water cycling and habitat provision) provided by the catchment’s lands and forests and waters (Millennium Ecosystem Assessment 2005).

The following pages of this report are a compilation of that work and contain information on surface water quality, riparian conditions, land cover, stewardship activity and hazard land and water resources protection.

2. Surface Water Quality Conditions

Surface water quality conditions in the Otter Lake and Creek 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 1 shows the locations of monitoring sites in the catchment. 

Figure 1 Water quality monitoring sites on Otter Lake and Creek
Figure 1 Water quality monitoring sites on Otter Lake and Creek

Otter Lake and Creek Water Quality

Water Quality Rating

The water quality rating for Otter Lake and Otter Creek (OTT-01) is “Fair” (Table 1) as 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. Each parameter is evaluated against established guidelines to determine water quality conditions. Those parameters that frequently exceed guidelines are presented below. Analysis of the data has been broken into two periods; 2003 to 2008 and 2009 to 2014 to examine if conditions have changed between these periods. Table 1 shows the overall rating for the monitored surface water quality sites within the Otter Creek catchment and Table 2 outlines the Water Quality Index (WQI) scores and their corresponding ratings. It should be noted that Otter Lake WQI stayed within the Fair rating range, however the score dropped from 77 to 65, which is the lowest rating in that category before moving to a poor rating. 

Table 1 Water Quality Index ratings for the Otter Creek Catchment
Sampling SiteLocation 2003-2008Rating 
RVL-26Otter Lake (2 deep water sites)77Fair
OTT-01Otter Creek at Highway 2966Fair
Sampling SiteLocation 2009-2014Rating 
RVL-26Otter Lake (2 deep water sites)65Fair
OTT-01Otter Creek at Highway 2974Fair
Table 2 Water Quality Index ratings and corresponding index scores (RVCA terminology, original WQI category names in brackets)
RatingIndex Score
Very Good (Excellent)95-100
Good80-94
Fair65-79
Poor (Marginal)45-64
Very Poor (Poor)0-44

 

2) a. Otter Lake Water Quality

Surface water quality conditions in Otter Lake (RVL-26) have been monitored by RVCA’s Watershed Watch Program since 2003. Data from two deep point sites have been used to calculate the WQI rating for Otter Lake, which was determined to be “Fair” (Table 1). Moderate nutrient concentrations, good oxygen availability, clear water and occasionally elevated pH levels contributed to the 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 seven 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 deep point sites. However, they do provide important information on water quality conditions in the near shore areas. For locations of shoreline sites please see Figure 1.

The 2003 Otter Lake State of the Lake Environment Report (Rideau Valley Conservation Authority, 2005) noted that Otter Lake had a moderate concentration of nutrients, generally suitable fish habitat conditions and good water clarity. The data presented in this report indicates that this continues to be the case and that a proactive cautionary program of best management practices is important to ensure the protection of the lake environment.

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.

At the Deep Points

TP and TKN sampling results are presented in Figures 2 to 5. In the 2003 to 2008 period, 100 percent of samples analyzed for TP were less than the TP guideline and stayed fairly consistent at 97 percent in the 2009 to 2014 period. The average TP concentration slightly increased from 0.009 mg/l to 0.010 mg/l. TKN concentrations were fairly normal with 97 percent of reported results below the TKN guideline in the first period (2003-2008); this decreased to 89 percent of samples in the 2009 to 2014 period. The average TKN concentration declined from 0.411 mg/l to 0.404 mg/l (Table 3).

 
Figure 2 Total phosphorous sampling results at deep point sites on Otter Lake, 2003-2008
Figure 2 Total phosphorous sampling results at deep point sites on Otter Lake, 2003-2008 
Figure 3 Total phosphorous sampling results at deep point sites on Otter Lake, 2009-2014
Figure 3 Total phosphorous sampling results at deep point sites on Otter Lake, 2009-2014
 
Figure 4 Total Kjeldahl nitrogen sampling results at deep point sites on Otter Lake, 2003-2008
Figure 4 Total Kjeldahl nitrogen sampling results at deep point sites on Otter Lake, 2003-2008
Figure 5 Total Kjeldahl nitrogen sampling results at deep point sites on Otter Lake, 2009-2014
Figure 5 Total Kjeldahl nitrogen sampling results at deep point sites on Otter Lake, 2009-2014 
 
Table 3 Summary of nutrient results for Otter Lake over two monitoring periods (2003-2008 and 2009-2014)
Total Phosphorous 2003-2008
SiteAverage (mg/l)Below Guideline No. Samples 
RVL-260.009100%34
Total Phosphorous 2009-2014
SiteAverage (mg/l)Below Guideline No. Samples 
RVL-260.0193%34
Total Kjeldahl Nitrogen 2003-2008
SiteAverage (mg/l)Below Guideline No. Samples 
RVL-260.41197%34
Total Kjeldahl Nitrogen 2009-2014
SiteAverage (mg/l)Below Guideline No. Samples 
RVL-260.40489%46

 

Average year to year concentrations have varied for both TP and TKN (Figures 6-9) from 2003-2008 and 2009-2014. An increase in average concentrations from 2008 to 2013 is visible, however all average TP and TKN results are below the guidelines in both monitoring periods (2003-2008 and 2009-2014). Overall, the data presented indicates that nutrient concentrations may be considered moderate in the mid-lake, deep water sites on Otter Lake. 

Figure 6 Average total phosphorous results at deep point sites on Otter Lake, 2003-2008
Figure 6 Average total phosphorous results at deep point sites on Otter Lake, 2003-2008
Figure 7 Average total phosphorous results at deep point sites on Otter Lake, 2009-2014
Figure 7 Average total phosphorous results at deep point sites on Otter Lake, 2009-2014
 
Figure 8 Average total Kjeldahl nitrogen results at deep point sites on Otter Lake, 2003-2008
Figure 8 Average total Kjeldahl nitrogen results at deep point sites on Otter Lake, 2003-2008
Figure 9 Average total kjeldahl nitrogen results at deep point sites on Otter Lake, 2009-2014
Figure 9 Average total kjeldahl nitrogen results at deep point sites on Otter Lake, 2009-2014
 
Around the Lake

The average nutrient concentrations at monitored shoreline sites around the lake vary from year to year (Figures 10-13). Please note that in the 2003-2008 monitoring period, sites were not sampled in 2004 and 2005. Sites B, C and F were sampled in 2003, 2006, 2007 and 2008 while sites A, D, E and G were only sampled in 2003 and 2008. In the second monitoring period (2009-2014) sites B, C and F were sampled every year, while sites A, D, E and G were sampled every fifth year.

Average total phosphorous concentrations are below the TP guideline at all sites in both monitoring periods (Figures 10 and 11), indicating nutrient enrichment does not to appear to be a problem in the monitored near shore areas.

TKN concentrations were also below the guideline at monitored sites; with the exception in 2013 at sites C and F which showed TKN concentrations above the guideline. Nutrient enrichment does not appear to be a problem in the monitored shoreline sites on Otter Lake (Figures 12 and 13). 

Figure 10 Average total phosphorous concentrations at shoreline monitoring sites in Otter Lake, 2003-2008
Figure 10 Average total phosphorous concentrations at shoreline monitoring sites in Otter Lake, 2003-2008 
Figure 11 Average total phosphorous concentrations at shoreline monitoring sites in Otter Lake, 2009-2014
Figure 11 Average total phosphorous concentrations at shoreline monitoring sites in Otter Lake, 2009-2014
 
Figure 12 Average total Kjeldahl nitrogen concentrations at shoreline monitoring sites in Otter Lake, 2003-2008
Figure 12 Average total Kjeldahl nitrogen concentrations at shoreline monitoring sites in Otter Lake, 2003-2008
Figure 13 Average total Kjeldahl nitrogen concentrations at shoreline monitoring sites in Otter Lake, 2009-2014
Figure 13 Average total Kjeldahl nitrogen concentrations at shoreline monitoring sites in Otter Lake, 2009-2014
 
Summary

Otter Lake nutrient concentrations are generally below the guidelines, with few exceedances. Average TP and TKN results (Table 3) are comparable to the 2003 Otter Lake State of the Lake Environment Report (Rideau Valley Conservation Authority, 2005) with TP concentrations of about .010 mg/l and TKN concentrations of about .445 mg/l.

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 exceedances. Nutrient exceedances may be partially attributed to the natural aging of a lake and basin characteristics. All residents can help reduce 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.

Water Clarity

Water clarity is measured using a Secchi disk during each deep point sample. Table 4 summarizes the recorded depths and shows that all readings have exceeded the minimum PWQO of 2 metres 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. The average Secchi depth increased from 5.8 metres (2003- 2008) to 6.4 metres (2009-2014). Figures 14 and 15 show that no individual reading has been below the guideline and measured depths range from 3.5 metres (Figure 15) to 12.5 metres (Figure 15). It should be noted that Secchi depths in many waterbodies have been influenced by the colonization of zebra mussels resulting in clearer waters than may have been seen prior to the introduction of this species; zebra mussels have been reported in Otter Lake since 2001.

Table 4 Summary of Secchi depths recorded at the deep point sites on Otter Lake, 2003-2008 and 2009-2014
Secchi Depth 2003-2008
SiteAverage Above Guideline No. Samples
RVL-265.8100%32
Secchi Depth 2009-2014
SiteAverage Above Guideline No. Samples
RVL-266.4100%43
 
Figure 14 Recorded Secchi depths at the deep point sites on Otter Lake, 2003-2008
Figure 14 Recorded Secchi depths at the deep point sites on Otter Lake, 2003-2008
Figure 15 Recorded Secchi depths at the deep point sites on Otter Lake, 2009-2014
Figure 15 Recorded Secchi depths at the deep point sites on Otter Lake, 2009-2014
 
Summary

Waters on Otter Lake are very 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). The 2003 Otter Lake State of the Lake Environment Report (Rideau Valley Conservation Authority, 2005) reported Secchi depths between 2.7 and 5.6 metres. The increase in water clarity can likely be attributed to the establishment of zebra mussels found in Otter Lake. 

Fish Habitat

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

Dissolved Oxygen and Temperature

The red bars in Figures 16-19 show the depths where suitable conditions exist for cool water fish species (temperature less than 25°C and dissolved oxygen greater than 4 mg/l) at the monitored deep point sites (RVL-26DP1 and RVL-26DP3). The vertical axis represents the total lake depth at each site where the profile is taken. Suitable habitat conditions increased over the two time periods from an average of 21.5 metres at RVL-26DP1 (Figure 16) in 2003-2008 period to 24.1 metres (Figure 18) in the 2009-2014 period. Deep point site RVL-26DP3 increased from and 21.9 metres (Figure 17) in 2003-2008 period to 24.9 metres (Figure 19) in the 2009-2014 monitoring period. 

Figure 16 Depths suitable for warm water fish species at site RVL-26DP1, 2003-2008
Figure 16 Depths suitable for warm water fish species at site RVL-26DP1, 2003-2008
Figure 17 Depths suitable for warm water fish species at site RVL-26DP3, 2003-2008
Figure 17 Depths suitable for warm water fish species at site RVL-26DP3, 2003-2008
 
Figure 18 Depths suitable for warm water fish species at site RVL-26DP1, 2009-2014
Figure 18 Depths suitable for cool water fish species at site RVL-26DP1, 2009-2014
Figure 19 Depths suitable for warm water fish species at site RVL-26 DP3 2009-2014
Figure 19 Depths suitable for cool water fish species at site RVL-26 DP3 2009-2014
pH

pH is a basic water quality parameter used to assess the acidity of water, an important factor for aquatic life. Figures 20 and 21 show pH concentrations in Otter Lake while Figures 22 and 23 summarize average concentrations by year.

Figure 20 pH concentrations at the deep point sites on Otter Lake, 2003-3008
Figure 20 pH concentrations at the deep point sites on Otter Lake, 2003-2008 
Figure 21 pH concentrations at the deep point sites on Otter Lake, 2009-2014
Figure 21 pH concentrations at the deep point sites on Otter Lake, 2009-2014
 
Figure 22 Average pH concentrations at the deep point sites on Otter Lake, 2003-2008
Figure 22 Average pH concentrations at the deep point sites on Otter Lake, 2003-2008
Figure 23 Average pH concentrations at the deep point sites on Otter Lake, 2009-2014
Figure 23 Average pH concentrations at the deep point sites on Otter Lake, 2009-2014
 

The majority of samples for both time periods were within guidelines established by the PWQO which state that pH should be between 6.5 and 8.5 to protect aquatic life and prevent irritation for anyone using the waters for recreational purposes (Table 5). Average results border on the upper limit of the guideline and there was very little change between both monitoring periods indicating that elevated pH is a feature of this lake. Surface water’s that are found to be more alkaline (higher pH) can generally be attributed to the geology rather than anthropogenic activities. Biological activities such as photosynthesis may also affect pH. 

Table 5 Summary of pH results at the deep point sites on Otter Lake, 2003-2008 and 2009-2014 
pH 2003-2008
SiteAverageWithin GuidelineNo. Samples
RVL 268.475%28
pH 2009-2014
SiteAverageWithin GuidelineNo. Samples
RVL-268.376%46
Summary

Overall the water chemistry data at the deep point describes suitable habitat conditions for warm water fish species such as yellow perch, walleye and pike. There is some evidence that the warming of the water column in the late summer/fall may limit the amount of habitat for some sensitive species. pH conditions are typically on the upper end of the range recommended for the protection of aquatic life. Overall, the data indicates a healthy environment for aquatic species.

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. In both monitoring periods (2003-2008 and 2009-2014) all samples were below the E. coli guideline of 100 colony forming units (CFU) per 100 ml set by the PWQO. Across the lake for both monitoring periods the count at the geometric mean[2] was only 2 CFU/100ml (Table 6).

Table 6 Summary of E. coli results for Otter Lake, 2003-2008 and 2009-2014
E. Coli 2003-2008
SiteGeometric Mean (CFU/100ml)Below GuidelineNo. Samples
RVL-262100%20
E. Coli 2009-2014
SiteGeometric Mean (CFU/100ml)Below GuidelineNo. Samples
RVL-262100%21
 
Figure 24 Geometric mean of shoreline sites monitored on Otter Lake, 2003-2008
Figure 24 Geometric mean of shoreline sites monitored on Otter Lake, 2003-2008
Figure 25 geometric mean of shoreline sites monitored on Otter Lake, 2009-2014
Figure 25 Geometric mean of shoreline sites monitored on Otter Lake, 2009-2014
 

Figures 24 and 25 show the distribution of counts across all shoreline sites. All sites fall well below the guideline of 100 CFU/100ml. This is consistent with E. coli results from the 2003 Otter Lake State of the Lake Environment Report (Rideau Valley Conservation Authority, 2005) that indicated an average of 2.5 CFU/100ml. 

Summary

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

2) b. Otter Creek Water Quality

There is one stream site on Otter Creek monitored in the Otter Lake and Creek catchment (OTT-01, Figure 1). Analysis of the data has been broken into two periods, 2003-2008 and 2009-2014, to examine if conditions have changed within this timeframe. Water quality at this site is reported as “Fair” (Table 1). The score at this site is largely influenced by elevated nutrient concentrations, metals and high bacterial counts. For more information on the CCME WQI, please see the Middle Rideau Subwatershed Report 2015.

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) and ammonia (NH3) are used as secondary indicators of nutrient loadings. RVCA uses a guideline of 0.500 mg/l to assess TKN[1] and the PWQO of 0.020 mg/l to assess ammonia concentrations at the monitored site.

Tables 7, 8 and 9 summarize average nutrient concentrations at monitored sites within the Otter Lake and Creek catchment and show the proportion of results that meet the guidelines.

Table 7 Summary of total phosphorous results for Otter Creek, 2003-2008 and 2009-2014. Highlighted values indicate average concentrations that exceed the guideline 
Total Phosphorous 2003-2008
SiteAverage (mg/l)Below GuidelineNo. Samples
OTT-010.04129%42
Total Phosphorous 2009-2014
SiteAverage (mg/l)Below GuidelineNo. Samples
OTT-010.03059%37
Table 8 Summary of total Kjeldahl nitrogen results for Otter Creek, 2003-2008 and 2009-2014. Highlighted values indicate average concentrations that exceed the guideline 
Total Kjeldahl nitrogen 2003-2008
SiteAverage (mg/l)Below GuidelineNo. Samples
OTT-010.71217%42
Total Kjeldahl nitrogen 2009-2014
SiteAverage (mg/l)Below GuidelineNo. Samples
OTT-010.67216%37
Table 9 Summary of Ammonia results for Otter Creek, 2003-2008 and 2009-2014. Highlighted values indicate average concentrations that exceed the guideline 
Ammonia 2003-2008
SiteAverageBelow GuidelineNo. Samples
OTT-010.05858%12
Ammonia 2009-2014
SiteAverageBelow GuidelineNo. Samples
OTT-010.01658%12

 

Elevated TP results were a regular occurrence in the 2003-2008 monitoring period at site OTT-01. The 2009-2014 monitoring period saw an improvement with less exceedances. Site OTT-01 had 29 percent of samples that were below the guideline in the 2003-2008 period (Figure 26); this increased to 59 percent of samples in the 2009-2014 period (Figure 27). The average TP concentration also decreased from 0.041 mg/l to 0.030 mg/l (Table 7).

 

Figure 26 Total phosphorous concentrations in Otter Creek, 2003-2008
Figure 26 Total phosphorous concentrations in Otter Creek, 2003-2008
Figure 27 Total phosphorous concentrations in Otter Creek, 2009-2014
Figure 27 Total phosphorous concentrations in Otter Creek, 2009-2014
 

TKN results show that the bulk of results exceeded the guideline (Figures 28 and 29); there were few samples (17 percent) below the guideline in the 2003-2008 period and this declined to only 16 percent in the 2009-2014 period. The average concentration was generally elevated and decreased from 0.712 mg/l to 0.672 mg/l (Table 8).

Figure 28 Total Kjeldahl nitrogen concentrations in Otter Creek, 2003-2008
Figure 28 Total Kjeldahl nitrogen concentrations in Otter Creek, 2003-2008
Figure 29 Total Kjeldahl nitrogen concentrations in Otter Creek, 2009-2014
Figure 29 Total Kjeldahl nitrogen concentrations in Otter Creek, 2009-2014
 

The trend of elevated nutrients is also observed in NH3 data, as results at this site were generally above the guideline of 0.020 mg/l (Figures 30 and 31); the proportion of samples below the guideline remained the same with 58 percent. However, as observed with TP and TKN, this was accompanied by a decrease in the average concentration from 0.058 mg/l (2003-2008) to 0.016 mg/l (2009-2014).

Figure 30 Ammonia concentrations in Otter Creek, 2003-2008
Figure 30 Ammonia concentrations in Otter Creek, 2003-2008
Figure 31 Ammonia concentrations in Otter Creek, 2009-2014
Figure 31 Ammonia concentrations in Otter Creek, 2009-2014
 
Summary

The data shows that nutrient enrichment is a feature of Otter Creek. High nutrient concentrations can help stimulate the growth of algae blooms and other aquatic vegetation in a waterbody and deplete oxygen levels as the vegetation dies off. It is important to reduce human impacts wherever possible. Strategies to reduce nutrient inputs may include diversion of runoff to the creek and enhanced shoreline buffers.

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 10 summarizes the geometric mean[2] for the monitored site on Otter Creek and shows the proportion of samples that meet the E. coli guideline of 100 CFU/100 ml. The geometric mean with respect to the guideline for the two periods (2003-2008 and 2009-2014) is shown in Figures 32 and 33 respectively.

Table 10 Summary of E. coli results for Otter Creek, 2003-2008 and 2009-2014. Highlighted values indicated average concentrations have exceeded the guideline
E. coli 2003-2008
SiteGeometric Mean (CFU/100ml)Below GuidelineNo. Samples
OTT-0131321%42
E. coli 2009-2014
SiteGeometric Mean (CFU/100ml)Below GuidelineNo. Samples
OTT-0111546%37

 

E. coli results at site OTT-01 indicate bacterial counts are frequently above the E. coli guideline. The proportion of samples below the guideline improved from 21 percent (Figure 32) to 46 percent (Figure 33). Reduced counts are also observed at the geometric mean which declined from 313 CFU/100ml to 115 CFU/100ml (Table 10).

Figure 30 E. coli results on Otter Creek, 2003-2008
Figure 32 Geometric mean of E. coli results on Otter Creek, 2003-2008
Figure 31 E. coli results on Otter Creek, 2009-2014
Figure 33 Geometric mean of E. coli results on Otter Creek, 2009-2014
 
 
Summary

Results indicate that bacterial contamination is a concern in Otter Creek. There has been an improvement from the 2003-2008 monitoring period to the 2009-2014 monitoring period, however a majority of samples still exceed the PWQO. The count at the geometric mean is above the PWQO for both monitoring periods. Properly maintaining septic systems, enhancing shoreline buffers and restricting cattle access can help to improve E.coli levels in Otter Creek.

Metals

Of the metals routinely monitored in Otter Creek, aluminum (Al) and iron (Fe) occasionally reported concentrations above their respective PWQOs. In elevated concentrations, these metals can have toxic effects on sensitive aquatic species. Tables 11 and 12 summarize metal concentrations at the monitored site and show the proportion of samples that meet guidelines. Figures 34 to 36 show metal concentrations with respect to the guidelines for the two periods of interest, 2003–2008 and 2009–2014. For Al, the PWQO is 0.075 mg/l and for Fe it is 0.300 mg/l.

Results from OTT-01 shows that Al concentrations had some exceedances with 67 percent of samples below the guideline in the 2003-2008 period (Figure 34). This improved to 92 percent of samples in the 2009-2014 period (Figure 35). The average concentration of Al was 0.132 mg/l from 2003-2008 which exceeds the guideline. From 2009-2014 the average concentration improved to 0.025 mg/l which is below the guideline. 

Table 11 Summary of Aluminum results for Otter Creek, 2003-2008 and 2009-2014
Aluminum 2003-2008
SiteAverage (mg/l)Below Guideline No. Samples
OTT-010.13267%27
Aluminum 2009-2014
SiteAverage (mg/l)Below Guideline No. Samples
OTT-010.02592%25
Table 12 Summary of Iron results for Otter Creek, 2003-2008 and 2009-2014
Iron 2003-2008
SiteAverage (mg/l)Below GuidelineNo. Samples
OTT-010.24174%27
Iron 2009-2014
SiteAverage (mg/l)Below GuidelineNo. Samples
OTT-010.06892%25
 
Figure 32 Average aluminum concentrations in Otter Creek, 2003-2008
Figure 34 Average aluminum concentrations in Otter Creek, 2003-2008
Figure 35 Average iron concentrations in Otter Creek, 2009-2014
Figure 35 Average aluminum concentrations in Otter Creek, 2009-2014
 

Iron concentrations also exceeded the guideline. The proportion of samples below the guideline increased from 74 percent to 92 percent (Figures 36 and 37). Although there were observed exceedances, the average concentration did not exceed the guideline in both monitoring periods; 0.241 mg/l in 2003-2008 and .068 mg/l in 2009-2014. 

Figure 34 Average iron concentrations in Otter Creek, 2003-2008
Figure 36 Average iron concentrations in Otter Creek, 2003-2008
Figure 35 Average iron concentrations in Otter Creek, 2009-2014
Figure 37 Average iron concentrations in Otter Creek, 2009-2014
 
Summary

Overall, a general decline in metal concentrations was observed between the two periods of interest. Efforts should continue to be made to identify pollution sources and implement best management practices to reduce any inputs such as runoff, metal alloys, fungicides and pesticides to improve overall stream health and lessen downstream impacts.


[1] No Ontario guideline for TKN is presently available; however, waters not influenced by excessive organic inputs typically range from 0.100 to 0.500 mg/l, Environment Canada (1979) Water Quality Sourcebook, A Guide to Water Quality Parameters, Inland Waters Directorate, Water Quality Branch, Ottawa, Canada

[2] 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.

Prepared by the Otter Lake Landowners’ Association and its partners, the Otter Lake Sustainable Lake Plan (2015) outlines eight goals, 19 objectives and 79 action items identified by the lake community to maintain and improve the health of the Otter Lake watershed. 

The following section includes some of those identified action items taken from that document (as identified by an asterisk), which have implications for the sustainable use and management of the water resources of Otter Lake and RVCA’s monitoring, reporting, planning/regulations and stewardship programs. Refer to the Otter Lake Sustainable Lake Plan for a complete list of all actions listed in that document.

7. Opportunities/Actions

Water Quality

  • Continue to monitor E. coli, Nitrogen and Phosphorous levels in Otter Lake in conjunction with the RVCA and seek no net increase in their levels over time. Aim for the OLLA target of: less than 5 CFU/100ml for E.coli; less than 10 micrograms for Phosphorous and between 200 to 500 µg/L for Nitrogen and report surface water quality results back to the Otter Lake community*
  • Consider expansion of surface water quality testing to include periodic sampling of the in/outflow creeks of Otter Lake*
  • Review RVCA Watershed Watch monitoring of surface water quality on Otter Lake
  • Continue to promote the voluntary septic system re-inspection program that the Township of Rideau Lakes introduced in 2007*
  • Work with the Township of Rideau Lakes to establish a mandatory sewage system inspection program on Otter Lake with an associated educational program and seek funding to provide financial assistance to landowners for repair or upgrades to their systems*
  • Continue to offer septic repair/replacement project funding provided by the Rideau Valley Rural Clean Water Program to landowners
  • Educate the Otter Lake community about septic system care by providing information about sewage system maintenance (i.e., when to pump out septic systems and holding talks)
  • Continue efforts to reduce pollutant loadings to Otter Lake through education about the application of shoreline, stormwater and agricultural best management practices; also consider using low impact development (LID) methods to improve the quality and reduce the amount of stormwater runoff reaching the lake ecosystem. This may be particularly beneficial in areas with extensive impervious surfaces (i.e., asphalt, concrete, buildings, and severely compacted soils) or on sensitive waterfront properties (with steep slopes/banks, shallow/impermeable soils)
  • Continue efforts to identify pollution sources along Otter Creek that may be contributing to the poor benthic invertebrate rating and reduce the frequently high nutrient concentrations and bacterial counts and occasional metal exceedances through ongoing monitoring and implementation of best management practices such as diverting runoff, enhancing shoreline buffers, limiting the use of fertilizers and pesticide applications and restricting livestock access 
  • Continue to promote the protection of the water resources of Otter Lake and Creek and its tributaries through implementation of municipal and agency land use planning and development policies and practices

Development

  • Collectively work with approval authorities (Township of Rideau Lakes, Conservation Authority, the Health Unit and Mississippi-Rideau Septic System Office) and the Otter Lake Landowners’ Association to consistently implement current land use planning and development policies for water quality and shoreline protection adjacent to Otter Lake and Creek and other catchment streams (e.g., a minimum 30 metre development setback from water)
  • Explore ways and means to more effectively enforce and implement conditions of land-use planning and development approval to achieve net environmental gains (particularly with respect to rehabilitating or protecting naturally vegetated shorelines and water quality)
  • Encourage Committees of Adjustment to take advantage of technical and environmental information and recommendations forthcoming from planning and environmental professionals
  • Municipalities and agencies are encouraged to strengthen natural heritage and water resources official plan policies and zoning provisions (water setbacks, frontage and naturalized shorelines and wetland protection) where deemed appropriate
  • Municipal and agency planners together with development proponents are to use the 2014 Site Evaluation Guidelines to inform decision-making about the application of development setbacks on lots with shallow soils/bedrock, steep slopes and sparse vegetation cover along with the use of the appropriate, development related, best management practices
  • Utilize RVCA subwatershed and catchment reports to help develop/revise official plan policies to protect surface water resources and the natural environment (including woodlands, wetlands and shoreline cover)
  • Consider establishing RVCA regulations limits to protect additional wetlands

Shorelines

  • Provide property owners with an assessment of the condition of their shoreline and recommendations for improvement using the results of the 2015 Otter Lake Shoreline Assessment*
  • Partner with the RVCA to promote its Shoreline Naturalization Program to re-naturalize altered shoreline*
  • RVCA and its partners (Rideau Lakes Township and the Otter Lake Landowners’ Association) are to continue educating landowners about the value and importance of headwater drainage features, natural shorelines and waterfront property best management practices with respect to shoreline use and development, septic system installation and maintenance and shoreline vegetation retention and enhancement
  • Protect the riparian buffer along the shoreline of Otter Lake and Otter Creek and other catchment streams (headwaters) during the development approvals process through adherence to and enforcement of municipal land-use policies and zoning standards
  • Target shoreline restoration at sites identified in this report (shown as “Other riparian land cover” in Figure 38 and “Potential Riparian/Shoreline Restoration” in Figure 77) and explore other restoration and enhancement opportunities along Otter Creek and its tribuatries

Water Levels

  • Establish a standard water level monitoring location on Otter Lake along with a “benchmark” water level and the authority responsible for measurements and continue with water level monitoring and reporting to the community*
  • Continue to leave to the forces of nature the natural flow of water into and out of Otter Lake, except in the case of expected high spring water levels, in which case the help of the RVCA and the Otter Creek Beaver Management Group may be needed to lower the beaver dams to increase the outflow of water through Otter Creek*
  • Communicate to the lake community any water level actions taken by the Beaver Management Group*
  • Continue to monitor if there is a need for greater water out flow capacity from Otter Lake than is currently provided by the existing culvert under the Otter Lake Road*

Aquatic Plants

  • Establish a volunteer-based aquatic invasive species (AIS) monitoring program and participate in the AIS Monitoring System to assist with early detection and management
  • Provide information about aquatic invasive species and the pathways for introduction along with AIS signage at the boat launch area off Highway 15*

Aquatic Habitat/Fisheries/wildlife

  • Request the Ministry of Natural Resources and Forestry to conduct a fish population assessment for Otter Lake*
  • Evaluate the littoral zone of Otter Lake identifying opportunities for shoreline enhancements to help protect and enhance the resident fish population and its aquatic habitat
  • Educate Otter Lake shoreline owners and visitors about fish habitat requirements, spawning schedules and near-shore and in-water activities that can disturb or destroy fish habitat and spawning sites, as well as the importance of re/naturalized shorelines*
  • Educate Otter Lake shoreline residents about best management practices to deal with species such as Canada Geese (e.g. replace grassy areas with native ground cover and shrubs)*

Lake Planning

  • Implement on a priority basis the identified actions listed in the Otter Lake Sustainable Lake Plan

 

watershed checkup

The RVCA is part of the provincial Watershed Checkup Program.