2.0 Rudsdale Creek Catchment: Water Quality Conditions

Surface water quality conditions in the Rudsdale Creek catchment are monitored by the Rideau Valley Conservation Authority's (RVCA) Baseline Water Quality Program. 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 Water quality monitoring sites on the Rudsdale Creek in the Rudsdale Creek Catchment

2.1 Rudsdale Creek: Water Quality Rating

There is one monitored water quality site on Rudsdale Creek in the Rudsdale Creek Catchment (RUD-01). The RVCA's water quality rating for it ranges from “Fair to Good” (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. 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.

2.1.1 Rudsdale 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]  concentrations in the Jock River.

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

Monitoring Site RUD-01

Elevated TP results occurred regularly at site RUD-01 throughout the monitoring period; 46% of samples were below the guideline (Figure 4). Average concentrations exceeded the guideline during the summer months, with lower concentrations (below guideline) observed in April and November (Figure 3). The average TP concentration was just above the guideline of 0.030 mg/l at 0.032 mg/l (Table 3). 

The majority of TKN results have also exceeded the guideline (Figure 6); only 10 percent of samples were below the guideline. The average concentration was 0.835 mg/l and exceeded the guideline of 0.500 mg/l (Table 4). Average monthly data showed a similar pattern to TP results, with the highest concentrations observed during the summer months, and lower concentrations in April and November (Figure 5).

There was no significant change^[2] in the sampled concentrations of TP or TKN at this site over the 2006-2017 period (Figures 4 and 6).

Figure 3  Average monthly total phosphorus concentrations in Rudsdale Creek, 2006-2017.

Figure 4  Distribution of total phosphorus concentrations in Rudsdale Creek, 2006-2017.

Figure 5  Average monthly total Kjeldahl nitrogen concentrations in Rudsdale Creek, 2006-2017.

Figure 6  Distribution of total Kjeldahl nitrogen concentrations in Rudsdale Creek, 2006-2017

Summary of Rudsdale Creek Nutrients

Results of  the monitored site on Rudsdale Creek shows that nutrient enrichment is a feature of this creek.  Elevated nutrients may result in nutrient loading downstream and to the Tay River. 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 should be noted that this creek is fed by extensive wetlands; this wetland complex is naturally nutrient rich and is likely a notable contributor to naturally elevated nutrient conditions. Development in this area is also minimal but there is a large portion of agricultural land; 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 within this creek.  

2.1.2 Rudsdale Creek 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 as a guideline. 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 site on Rudsdale 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 7 and 8.

Monitoring Site RUD-01

E. coli counts at site RUD-01 show that there has been no significant trend in bacterial counts (Figure 8). The count at the geometric mean was 56 CFU/100ml (Table 5), and majority of results (68 percent) were below the E. coli guideline.  Figure 7 shows that counts are generally highest in late summer (August); this can likely be attributed to warm weather and reduced flow conditions.

Figure 7  Geometric mean of monthly E. coli counts in Rudsdale Creek, 2006-2017

Figure 8  Distribution of E. coli counts in Rudsdale Creek, 2006-2017

Summary of Rudsdale Creek Bacterial Contamination

Bacterial contamination does not appear to be a significant concern in Rudsdale Creek.  As indicated by Figure 8 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 Rudsdale Creek into the future.

2.1.3 Rudsdale Creek: Metals

Of the metals routinely monitored in Rudsdale 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 6 summarizes Fe concentrations within the creek as well as show the proportion of samples that meet guidelines. Figures 9 and 10 show Fe concentrations with respect to the guidelines for the monitoring period, 2006-2017. 

Monitoring Site RUD-01

The average Fe concentrations in site RUD-01 was 0.503 mg/l and exceeded the guideline (PWQO). Forty-three percent of samples were below the guideline and there was no significant change in Fe concentrations across the monitoring period (Table 6, Figure 10).  Monthly concentrations were elevated through the summer months (Figure 9).

Figure 9  Average monthly iron concentrations in Rudsdale Creek, 2006-2017.

Figure 10  Distribution of iron concentrations in Rudsdale Creek, 2006-2017.

Summary of Rudsdale Creek Metals

In Rudsdale Creek there is evidence of increased metal concentration above respective guidelines, 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.