2. Surface Water Quality Conditions

Surface water quality conditions in the Rosedale Creek catchment are monitored by the Rideau Valley Conservation Authority’s (RVCA) Baseline Water Quality Monitoring 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 1 shows the location of the monitoring sites in the catchment.

Rosedale Creek Water Quality

Water Quality Rating

The water quality rating for Rosedale Creek sites (ROS-01 and ROS-02) are both “Fair” (Table 1) as determined by the Canadian Council of Ministers of the Environment (CCME) Water Quality Index and are largely influenced by frequent high nutrient concentrations, occasional metal exceedances and high bacterial counts. 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. The water quality score at both sites has improved and ROS-01 has seen its rating change from “Poor” to “Fair”. Table 1 shows the overall rating for the monitored surface water quality sites within the Rosedale Creek catchment and Table 2 outlines the Water Quality Index (WQI) scores and their corresponding ratings.

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 NH3 concentrations in Rosedale Creek.

Tables 3, 4 and 5 summarize average nutrient concentrations at monitored sites within the Rosedale Creek catchment and show the proportion of results that meet the guidelines.

ROS-01

The majority of samples at site ROS-01 were above the TP guideline from 2003-2008; however the amount of exceedances decreased in the 2009-2014 monitoring period (Figures 2 and 3). The number of samples below the guideline increased from 36 percent in 2003-2008 to 62 percent from 2009-2014. The average TP concentrations decreased from 0.076 mg/l (2003–2008) to 0.030 mg/l (2009–2014).

TKN concentrations show that the bulk of results exceeded the guideline (Figures 4 and 5); there were few samples (19 percent) below the guideline in the 2003-2008 period and this slightly increased to 27 percent in the 2009-2014 period. The average concentration was generally elevated but decreased from 0.662 mg/l to 0.578 mg/l (Table 4).

In the 2003-2008 reporting period half of NH3 results were below the guideline with an average concentration of 0.021 mg/l (Figure 6). The percentage of results remained the same for both monitoring periods, with 50 percent of samples below the guideline. The average concentration in 2009-2014 decreased to 0.017 mg/l (Figure 7).

ROS-02

Elevated TP results were an occasional occurrence at site ROS-02; 71 percent of samples were below the guideline in the 2003-2008 period (Figure 2); this increased to 76 percent of samples in the 2009-2014 period (Figure 3). The average TP concentration also decreased slightly from 0.030 mg/l (2003- 2008) to 0.025 mg/l (2009-2014).

The bulk of TKN results have exceeded the guideline (Figure 4 and 5), with 29 percent of samples below the guideline in the 2003-2008 period, decreasing to 22 percent of samples below the guideline from 2009-2014. The average concentration was elevated and increased from 0.572 mg/l to 0.620 mg/l (Table 4).

The results for NH3 indicate that exceedances were an occasional occurrence. The proportion of results that were below the guideline were 75 percent in 2003-2008 (Figure 6); this increased to 83 percent in the 2009-2014 reporting periods (Figure 7). The average NH3 concentration increased slightly from 0.010 mg/l to 0.012 mg/l (Table 5). 

Figure 2 Total phosphorous concentrations in Rosedale Creek, 2003-2008

Figure 3 Total phosphorous concentrations in Rosedale Creek, 2009-2014

 

Figure 4 Total Kjeldahl nitrogen concentrations in Rosedale Creek, 2003-2008

Figure 5 Total Kjeldahl nitrogen concentrations in Rosedale Creek, 2009-2014

Figure 6 Ammonia concentrations is Rosedale Creek, 2003-2008

Figure 7 Ammonia Concentrations in Rosedale Creek, 2009-2014

 

Summary

Nutrient enrichment is a feature of Rosedale Creek. Overall average nutrient concentrations have decreased over the two reporting periods. Total Kjeldahl nitrogen remains above the PWQO for sites ROS-01 and ROS-02, whereas total phosphorous and ammonia have average concentrations below their guidelines in the second reporting period. Elevated nutrients may result in nutrient loading downstream. 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. Best management practices such as an enhanced shoreline buffer, preventing the use of fertilizers and restricting cattle access can help to reduce nutrient enrichment in Rosedale 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 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 6 summarizes the geometric mean^[2] for the monitored sites on Rosedale 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 two periods, 2003-2008 and 2009- 2014, are shown in Figures 8 and 9 respectively.

ROS-01

E. coli counts at site ROS-01 indicate a slight improvement with regard to bacterial contamination. The proportion of samples below the guideline increased from 26 percent (Figure 8) to 30 percent (Figure 9). The count at the geometric mean decreased from 180 CFU/100ml in 2003-2008 to 156 CFU/100ml from 2009-2014 (Table 6). Although the count at the geometric mean decreased, the results exceeded the guideline for both reporting periods. 

ROS-02

Elevated E.coli counts at site ROS-02 were a common occurrence. The proportion of samples below the guideline did increase from 36 percent (Figure 8) from 2003-2008 to 43 percent (Figure 9) from 2009-2014. The geometric mean also did decrease between the two monitoring periods from 186 CFU/100ml to 146 CFU/100ml (Table 6). Although E.coli counts did decrease, the geometric mean was above the guideline for both reporting periods. 

Figure 8 Geometric mean of E.coli results in Rosedale Creek, 2003-2008

Figure 9 Geometric mean of E.coli results in Rosedale Creek, 2009-2014

 

Summary

Bacterial contamination is a concern on Rosedale Creek. Both sites ROS-01 and ROS-02 have exceeded the guideline for both monitoring periods. The count at the geometric mean has decreased from the 2003-2008 to the 2009-2014 reporting period. Properly maintaining septic systems, enhancing shoreline buffers and restricting cattle access can help to improve E.coli levels in Hutton Creek.

Metals

Of the metals routinely monitored in Rosedale Creek, aluminum (Al), copper (Cu) and iron (Fe) occasionally reported concentrations above their respective PWQOs. In elevated concentrations, these metals can have toxic effects on sensitive aquatic species.

Tables 7, 8 and 9 summarize metal concentrations at sites ROS-01 and ROS-02 as well as show the proportion of samples that meet guidelines. Figures 10 to 15 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, Cu it is 0.005 mg/l and Fe it is 0.300 mg/l.

ROS-01

The Al concentrations in site ROS-01 exceeded the guideline. There were no results below the guideline (Figure 10) from 2003-2008, however this did improve to 56 percent (Figure 11) of results reporting below the guideline from 2009-2014. The average concentration decreased from 1.212 mg/l to 0.204 mg/l (Table 7). Although Al has declined, the average concertation is still above the guideline.

Copper concentrations occasionally exceeded the PWQO, with 78 percent of samples below the guideline in 2003-2008 (Figure 12). The Cu concentrations increased to 84 percent of samples being below the guideline in 2009-2014 (Figure 13). The average concentration of copper marginally decreased during the two reporting periods from 0.003 mg/l to 0.002 mg/l (Table 8). 

Results from ROS-01 indicated that Fe concentrations exceeded the guideline. The proportion of samples below the guideline increased from 4 percent to 80 percent (Figures 14 and 15). During the 2003-2008 reporting period Fe concentrations were well above the guideline with an average concentration of 1.480 mg/l. The average Fe concertation fell below the guideline in the 2009-2014 reporting period, with an average concertation of 0.245 mg/l (Table 9).

ROS-02

Results from ROS-02 show that Al concentrations had multiple exceedances with 6 percent of samples below the guideline in the 2003-2008 period (Figure 10). This improved to 56 percent of samples in the 2009-2014 period (Figure 11). The average concentration of Al was 0.231 mg/l from 2003-2008 and 0.099 mg/l from 2009-2014 (Table 7). Both monitoring periods had average concentrations which exceeded the guideline.

Copper concentrations have occasionally exceeded the guidelines. In the 2003-2008 period 94 percent of samples were below the guideline (Figure 14) and decreased to 84 percent of samples in the 2009–2014 period (Figure 15). The average concentrations (Table 8) decreased from 0.003 mg/l (2003–2008) to 0.001 mg/l (2009–2014). 

Iron concentrations also exceeded the guideline. The proportion of samples below the guideline increased from 29 percent to 84 percent (Figures 12 and 13). The average concentration of 0.366 mg/l during the 2003-2008 reporting period exceeded the guideline. The average concentration decreased to below the guideline in the 2009-2014 reporting period with an average of 0.140 mg/l (Table 9). 

Figure 10 Average aluminum concentrations in Rosedale Creek, 2003-2008

Figure 11 Average aluminum concentrations in Rosedale Creek, 2009-2014

 

Figure 12 Average copper concentrations in Rosedale Creek, 2003-2008

Figure 13 Average copper concentrations in Rosedale Creek, 2009-2014

 

Figure 14 Average iron concentrations in Rosedale Creek, 2003-2008

Figure 15 Average iron concentrations in Rosedale Creek, 2009-2014

 

Summary

Aluminum, copper and iron concentrations all declined from the 2003-2008 monitoring period to the 2009-2014 period. Although these metals have declined, both ROS-01 and ROS-02 have average Al concentrations that are above the guideline. 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.