2. Surface Water Quality Conditions

Surface water quality conditions in the Rideau 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 site in the catchment.

Rideau Creek Water Quality

Water Quality Rating

The water quality rating for Rideau Creek (RCK-01) is “Fair” (Table 1) as determined by the Canadian Council of Ministers of the Environment (CCME) Water Quality Index and is largely influenced by high nutrient concentrations, metals 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. Table 1 shows the overall rating for the monitored surface water quality sites within the Black 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 Barbers Creek.

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

The majority of samples at site RCK-01 were below the TP guideline for both time periods (Figures 2 and 3), 88 percent of samples were below the guideline in the 2003–2008 period, and this increased to 92 percent of samples in the 2009–2014 period. Average TP concentration decreased from 0.024 mg/l (2003–2008) to 0.021 mg/l (2009–2014) (Table 3).

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

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

 

The bulk of TKN results exceeded the guideline (Figures 4 and 5); there were few samples (29 percent) below the guideline in the 2003-2008 period and this declined to having 16 percent of samples below the guideline in the 2009-2014 period. Both monitoring periods average concentrations were above the guideline and increased from 0.622 mg/l to 0.604 mg/l (Table 4). 

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

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

 

A majority of NH3 results were below the guideline in both monitoring periods. The percentage of results below the guideline in 2003-2008 was 73 percent, this increased to 83 percent in the 2009-2014 period (Figure 4 and 5). The average concentration marginally increased from 0.008 mg/l to 0.011 mg/l (Table 5).

Figure 6 Ammonia concentrations in Rideau Creek, 2003-2008

Figure 7 Ammonia concentrations in Rideau Creek, 2009-2014

 

Summary

Nutrient enrichment is an occasional occurrence on Rideau Creek. Both TP and NH3 have few exceedances over both reporting periods. The TKN results however did exceed the guideline a majority of the time. The frequent elevated TKN concentrations may be influenced by organic matter held by wetland areas found upstream in the Middle Rideau Subwatershed, resulting in naturally high concentrations of organic nitrogen. 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. 

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 site on Rideau 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.

E.coli results at site RCK-01 indicate that bacterial counts are occasionally above the E.coli Guideline. The proportion of samples below the guideline slightly increased from 63 (Figure 8) percent to 65 percent (Figure 9). E.coli counts were below the guideline for both monitoring periods, however the geometric mean slightly increased from 52 CFU/100ml to 54 CFU/100ml (Table 6). 

Figure 8 E.coli concentrations in Rideau Creek, 2003-2008

Figure 9 E.coli concentrations in Rideau Creek, 2009-2014

 

Summary

This data shows that E.coli results occasionally exceed the guidelines at site RCK-01 in Rideau Creek. The geometric mean is below the PWQO for both monitoring periods. There has been a slight increase in E.coli counts between 2003-2008 and 2009-2014. Properly maintaining septic systems, enhancing shoreline buffers and restricting cattle access can help to improve and maintain E.coli counts in Rideau Creek.

Metals

Of the metals routinely monitored in Rideau 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 7 and 8 summarize metal concentrations at the monitored site and show the proportion of samples that meet guidelines. Figures 10 to 13 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.

Aluminum concentrations at site RCK-01 has occasionally exceedance the PWQO with 37 percent of samples below the guideline in the 2003-2008 period (Figure 10) to 72 percent of samples below the guideline in the 2009-2014 period (Figure 11). The average concentration of Al was above the guideline in the first reporting period with an average of 0.097 mg/l, this decreased to below the guideline with a concentration of 0.049 mg/l in the second reporting period (Table 7). 

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

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

 

Results from RCK-02 shows that Fe concentrations had some exceedances with 70 percent of samples below the guideline in the 2003-2008 period (Figure 12). This improved to 96 percent of samples in the 2009-2014 period (Figure 13). The average concentration of Fe was 0.240 mg/l from 2003-2008 and 0.092 mg/l from 2009-2014 (Table 8). Both average concentrations were below the guideline. 

Figure 12 Average iron concentration in Rideau Creek, 2003-2008

Figure 13 Average iron concentrations in Rideau Creek, 2009-2014

 

Summary

A decline in metal concentrations was observed between the two periods of interest. Average concentrations are all below the PWQO. 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.