2. Surface Water Quality Conditions

Surface water quality conditions in the Black 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.

Black Creek Water Quality

Water Quality Rating

The water quality rating for the Black Creek (COC-02) 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 COC-02 were above the TP guideline for both time periods (Figures 2 and 3), 38 percent of samples were below the guideline in the 2003–2008 period, this declined to 35 percent of samples in the 2009–2014 period. Average TP concentration decreased from 0.037 mg/l (2003–2008) to 0.033 mg/l (2009–2014). 

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

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

 

All of the TKN results exceeded the guideline for both monitoring periods (2003-2008 and 2009-2014). The average concentration from 2003-2008 in Black Creek was 1.244 mg/l (Figure 4), this decreased to .994 mg/l (Figure 5) from 2009-2014. 

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

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

 

In the 2003-2008 reporting period a majority of NH3 results were below the guideline with an average concentration of 0.017 mg/l (Figure 6). The percentage of results below the guideline decreased from 67 percent in 2003-2008 to 10 percent. The average concentration in 2009-2014 increased to 0.032 mg/l (Figure 7). 

Figure 6 Ammonia concentrations in Black Creek, 2003-2008

Figure 7 Ammonia concentrations in Black Creek, 2009-2014

 

Summary

The data shows that nutrient enrichment continues to be a feature of Black Creek. Water quality guidelines for TP, TKN and NH3 are often exceeded at the monitored site on Black Creek. 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 Black 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 COC-02 indicate bacterial counts are frequently above the E. coli guideline. The proportion of samples below the guideline decreased from 63 percent (Figure 8) to 47 percent (Figure 9). E.coli counts increased between the two monitoring periods (2003-2008 and 2009-2014) with a geometric mean of 66 CFU/100ml to 104 CFU/100ml (Table 6). 

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

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

 

Summary

Bacterial contamination continues to be a concern at site COC-02 in Black Creek. E.coli counts have increased between the two monitoring periods (2003-2008 and 2009-2014), with the geometric mean being above the PWQO for the 2009-20014 reporting period. Properly maintaining septic systems, enhancing shoreline buffers and restricting cattle access can help to improve E.coli levels in Black Creek.

Metals

Of the metals routinely monitored in Black 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 the monitored site and 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 for Fe it is 0.300 mg/l. 

Results from COC-02 shows that Al concentrations had some exceedances with 22 percent of samples below the guideline in the 2003-2008 period (Figure 10). This improved to 69 percent of samples in the 2009-2014 period (Figure 11). The average concentration of Al was 0.128 mg/l from 2003-2008 which exceeds the guideline. From 2009-2014 the average concentration improved to 0.060 mg/l which is below the guideline. 

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

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

 

Copper concentrations occasionally exceeded the PWQO, with 89% of samples below the guideline in 2003-2008 (Figure 12). This decreased to 79% of samples being below the guideline in 2009-2014 (Figure 13). The average concentration of Cu marginally decreased during the two reporting periods from 0.003 mg/l to 0.002 mg/l (Table 8). 

Figure 12 Average copper concentration in Black Creek, 2003-2008

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

 

Iron concentrations also surpassed the PWQO guideline. The proportion of samples below the guideline increased from 52 percent to 79 percent (Figures 14 and 15). The average concentration of Fe in 2003-2008 reporting period was 0.309 mg/l which is above the guideline. Between 2009-2014 Fe concentrations decreased below the guideline to an average of 0.130mg/L (Table 9).  

Figure 14 Average Iron concentrations in Black Creek, 2003-2008

Figure 15 Average Iron concentrations in Black Creek, 2009-2014

 

Summary

Overall, a general decline in metal concentrations was observed between the two periods of interest, with the exception of copper which slightly increased. 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.