2.0 Port Elmsley Catchment: Water Quality Conditions

Surface water quality conditions in the Port Elmsley catchment are monitored by the Rideau Valley Conservation Authority (RVCA) Baseline Water Quality Monitoring Program. The baseline water quality program focuses on streams; data is collected for 22 parameters including nutrients (total phosphorus and total Kjeldahl nitrogen), 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 Water quality monitoring sites on the Tay River in the Port Elmsley Catchment  

2.1 Tay River: Water Quality Rating

There are two monitored water quality sites in Port Elmsely Catchment, both of which are on the main channel of the Tay River. The RVCA's water quality rating at both sites (TAY-11 and TAY-01) was reported as "Good" (Table 1) as determined by the Canadian Council of Ministers of the Environment (CCME) Water Quality Index.  "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.

The scores at these sites are largely influenced by few high nutrient concentrations and bacterial counts. For more information on the CCME WQI, please see the Tay River Subwatershed Report.

2.1.1 Tay River: 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 secondary indicators of nutrient loading. RVCA uses a guideline of 0.500 mg/l to assess TKN^[1] .

Tables 3 and 4 summarize average nutrient concentrations at monitored sites within the Port Elmsley catchment and show the proportion of results that meet the guidelines.

Monitoring Site TAY-11

Site TAY-11 is the most upstream site on the Tay River monitored in this catchment. It is in the Perth Wildlife Reserve downstream of the Tay Lagoons and upstream of the Tay Marsh. The majority of samples (90 percent) at this site from 2006-2017 were below the TP guideline (Figures 3 and 4). The average TP concentration at this site was 0.023 mg/l (Table 3).  Figure 3 shows that monthly average concentrations are highest from April to July, with a general reduction in concentrations from August to November.  The average concentrations exceeded the guideline in October, due to a single elevated sample in October 2007 (Figure 4). Overall a decrease was observed in TP concentrations through the 2006-2017 period².

TKN concentrations show that the bulk of results were elevated; only 36 percent of samples were below the guideline (Figure 6, Table 4). The average concentration over the 2006-2017 period was 0.590 mg/l (Table 4); monthly averages are comparable across the sampling seasons with the lowest concentrations observed in August and September (Figure 5). As with the TP data, average TKN concentrations are very high in October (Figure 5) due to the influence of an elevated sample in October 2007 (Figure 6).  There was no significant trend found in TKN results at this site.

Monitoring Site TAY-01

Site TAY-01 is downstream of TAY-11 and is the last monitored site before the Tay River flows into Lower Rideau Lake.  TP results were fairly low, the average concentrations was 0.021 and 92 percent of samples were below the guideline (Table 3, Figure 4).  Monthly TP concentrations followed a similar pattern to upstream site TAY-11, and were consistently below the guideline (Figure 3). A declining trend in TP concentrations was also observed in the data from this site.

The majority of TKN results exceeded the guideline (Figure 5 and 6), 40 percent of samples were below 0.500 mg/l (TKN Guideline) with an average concentration of 0.534 mg/l (Table 4). Average monthly concentrations were comparable and also followed a similar pattern to TAY-11 (Figure 5), August and September were the only months that had average concentrations below the guideline. No significant trend was observed in the 2006-2017 TKN dataset.

Figure 3 Average monthly total phosphorous concentrations in the Port Elmsly catchment, 2006-2017

Figure 4 Distribution of total phosphorous concentrations in the Port Elmsley catchment, 2006-201

Figure 5 Average monthly total Kjeldahl nitrogen concentrations in the Port Elmsley catchment, 2006-2017

Figure 6  Distribution of total Kjeldahl nitrogen concentrations in the Port Elmsley catchment, 2006-2017

Summary of Tay River Nutrients

The data collected in this catchment provides evidence that nutrient enrichment is not a significant concern in this reach of the Tay River.  TP and TKN concentrations are comparable between the two sites.  The majority of TP samples are below guidelines and declining trend in TP concentrations was noted at both sites.  Average TKN concentrations were just above the guideline and the majority of samples did exceed 0.500 mg/l.  The elevated TKN can likely be attributed to the significant wetland area in this catchment.  Wetlands hold a lot of nitrogen in their soils and can strongly influence the concentrations to overlying waters.  The reduction in TP concentrations should be taken as a positive sign that cumulative changes on the landscape have benefited water quality conditions. 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 continue best management practices such as minimizing storm water runoff, enhanced shoreline buffers, minimizing/discontinuing the use of fertilizers and restricting livestock access in upstream agricultural areas.  These practices can help to prevent nutrient pollution; protecting and enhancing water quality conditions within the Tay River and Lower Rideau Lake.

2.1.2 Tay River: E. 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. E. coli counts greater than this guideline indicate that bacterial contamination may be a problem within a waterbody.

Table 5 summarizes the geometric mean^[3] for the monitored sites within the Port Elmsley catchment 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 are shown in Figures 7 and 8 respectively.

Monitoring Site TAY-11

E. coli counts at site TAY-11 indicate little concern with regard to bacterial contamination. Sixty-nine percent of samples were below the guideline (Figures 7-8) and the count at the geometric mean was 53 CFU/100ml (Table 5). Monthly E. coli counts showed that the geometric mean was highest during the warmer months though all results were below the guideline; warm water temperature and low flow conditions are more favourable for bacterial growth. (Figure 7).  No trend was noted in E. coli counts over the 2006-2017 period.

Monitoring Site TAY-01

Elevated E. coli counts at site downstream site TAY-01 were also minimal. Sixty-eight percent of samples were below the guideline (Figure 8) from 2006-2017. The count at the geometric mean was 53 CFU/100ml (Table 5) and well below the guideline. As with site TAY-11, counts were highest during the summer months. The count at the geometric mean exceeded the guideline in July (Figure 7), this was strongly influenced by a single elevated sample in July 2017 (Figure 8).  There was no significant trend in E. coli data over the 2006-2017 period.

Figure 7 Geometric mean of E. coli results in the Port Elmsley catchment, 2006-2017

Figure 8 Distribution of E. coli counts in the Port Elmsley catchment, 2006-2017.

Summary of Tay River Bacterial Contamination

Bacterial contamination does not appear to be a significant concern in this reach of the Tay River. The majority of samples do not exceed the guideline and counts at the geometric mean are well below the guideline of 100 CFU/100ml. Best management practices such as enhancing shoreline buffers, limiting livestock access and minimizing runoff in both agricultural and developed areas can help to protect this reach of the Tay River into the future.