Wildlife

Water Quality

Ambient Water Quality Criteria for Colour in British Columbia: Technical Appendix

5. Wildlife

5.1 Effects

Several studies have found that species abundance and/or reproductive success of wildlife may be positively or negatively correlated with water colour. For example, negative relationships between breeding success of common loons and Pacific loons in Ontario, Quebec, Minnesota and Alaska and water colour have been demonstrated (Alvo et al. 1988; Heglund et al. 1994). Loons are sight feeders that generally feed on the nest lake. Thus, it is advantageous for loons to nest near relatively clearwater systems. Heglund et al. (1994) found that on average, Pacific loons occurred on lakes and ponds with colour values about two-thirds the values of lakes and ponds without loons (loons present ~50 - 75 mg/L Pt, loons absent ~80 - 120 mg/L Pt). Other species, however, have distributions that are positively correlated with water colour. The distribution of Blanding's Turtles (Emydoidea blandingii), Painted Turtles (Chrysemys picta), and Great Blue Herons (Ardea herodias) closely parallels the distribution of highly coloured acidic waters and peaty soils in Nova Scotia (Power et al. 1994). In all but one instance, Blanding's turtles were only found in lakes and streams with true colour >60 mg/L Pt. The association between turtle and heron abundance and water colour is likely related to the higher secondary productivity typical of highly coloured systems.

5.2 Literature Criteria

No water quality criteria for the protection of wildlife were found in the literature for either true or apparent colour.

5.3 Proposed Criteria

5.3.1 Apparent Colour

The 30-day mean transmission of white light shall be greater than or equal to 80% of background levels as measured historically or at appropriate reference sites. This criterion applies to freshwater, estuarine and marine aquatic systems. The 30-day mean calculation should be based on a minimum of five weekly samples taken over a period of 30 days. The appropriate methodology for determining transmission of white light is noted in section 4.3.1.

5.3.2 True Colour

The 30-day mean true colour of filtered water samples shall not exceed background levels by more than 5 mg/L Pt in clearwater systems (background levels less than or equal to 20 mg/L Pt) or 20% in coloured systems (background levels >20 mg/L Pt). This criterion applies to freshwater, estuarine and marine aquatic systems. The 30-day mean calculation should be based on a minimum of five weekly samples taken over a period of 30 days. The appropriate methodology for determining transmission of white light is noted in section 4.3.2.

5.4 Rationale

The limited wildlife effects information indicates that changes in water colour could lead to some species avoiding particular habitats. The available information is, however, insufficient to define numerical criteria for the protection of wildlife that would be different from the aquatic life criteria. The aquatic life criteria should be protective of wildlife because the changes in colour associated with declines in loon abundance and reproductive success (~50% increase in colour) are greater than those specified in the criteria. For monitoring programs, it is also cost efficient to use the same analytical protocols for different water uses.


	Water Quality Ambient Water Quality Criteria for Colour in British Columbia: Technical Appendix 5. Wildlife 5.1 Effects Several studies have found that species abundance and/or reproductive success of wildlife may be positively or negatively correlated with water colour. For example, negative relationships between breeding success of common loons and Pacific loons in Ontario, Quebec, Minnesota and Alaska and water colour have been demonstrated (Alvo et al. 1988; Heglund et al. 1994). Loons are sight feeders that generally feed on the nest lake. Thus, it is advantageous for loons to nest near relatively clearwater systems. Heglund et al. (1994) found that on average, Pacific loons occurred on lakes and ponds with colour values about two-thirds the values of lakes and ponds without loons (loons present ~50 - 75 mg/L Pt, loons absent ~80 - 120 mg/L Pt). Other species, however, have distributions that are positively correlated with water colour. The distribution of Blanding's Turtles (Emydoidea blandingii), Painted Turtles (Chrysemys picta), and Great Blue Herons (Ardea herodias) closely parallels the distribution of highly coloured acidic waters and peaty soils in Nova Scotia (Power et al. 1994). In all but one instance, Blanding's turtles were only found in lakes and streams with true colour >60 mg/L Pt. The association between turtle and heron abundance and water colour is likely related to the higher secondary productivity typical of highly coloured systems. *5.2 Literature Criteria* No water quality criteria for the protection of wildlife were found in the literature for either true or apparent colour. *5.3 Proposed Criteria* 5.3.1 Apparent Colour The 30-day mean transmission of white light shall be greater than or equal to 80% of background levels as measured historically or at appropriate reference sites. This criterion applies to freshwater, estuarine and marine aquatic systems. The 30-day mean calculation should be based on a minimum of five weekly samples taken over a period of 30 days. The appropriate methodology for determining transmission of white light is noted in section 4.3.1. 5.3.2 True Colour The 30-day mean true colour of filtered water samples shall not exceed background levels by more than 5 mg/L Pt in clearwater systems (background levels less than or equal to 20 mg/L Pt) or 20% in coloured systems (background levels >20 mg/L Pt). This criterion applies to freshwater, estuarine and marine aquatic systems. The 30-day mean calculation should be based on a minimum of five weekly samples taken over a period of 30 days. The appropriate methodology for determining transmission of white light is noted in section 4.3.2. *5.4 Rationale* The limited wildlife effects information indicates that changes in water colour could lead to some species avoiding particular habitats. The available information is, however, insufficient to define numerical criteria for the protection of wildlife that would be different from the aquatic life criteria. The aquatic life criteria should be protective of wildlife because the changes in colour associated with declines in loon abundance and reproductive success (~50% increase in colour) are greater than those specified in the criteria. For monitoring programs, it is also cost efficient to use the same analytical protocols for different water uses.