| Req ID | Category | Intent | Legal Status | Name | Subdomain(s) | Context | Conditions | Confidence |
|---|---|---|---|---|---|---|---|---|
| #Q001 | monitoring | operational | recommended | Colour Measurement Timeframe | other | As some of the compounds determining the colour of water are not very stable, measurements should be made within two hours of collection (Environment Canada 1989). | When analyzing water samples for true or apparent colour | high |
| #Q002 | monitoring | operational | mandatory | Turbidity Handling for True Colour Photometry | other | First, turbidity must be removed by either filtration or centrifugation (APHA 1992), or its contribution quantified | When matching apparatus photometric readings with visual judgments for true colour | high |
| #Q003 | monitoring | operational | guidance | Filtration Requirement for Turbid Waters | other | The common practice of filtration through 0.45 micron filters should be satisfactory for most waters, although repeated filtration may be required for very turbid waters. | When removing turbidity to measure true colour in highly turbid waters | high |
| #Q004 | treatment | treatment | recommended | Chlorine Application Point for THM Prevention | drinking water | In order to prevent the formation of trihalomethanes (THMs), the initial point of chlorine application should follow the coagulation/sedimentation process | When treating drinking water containing dissolved coloured substances | high |
| #Q005 | monitoring | reporting | recommended | 30-Day Mean Sampling Methodology (Apparent Colour, Aquatic Life) | aquatic life | The 30-day mean calculation should be based on a minimum of five weekly samples taken over a period of 30 days. | When calculating the 30-day mean transmission of white light for aquatic life | high |
| #Q006 | monitoring | operational | mandatory | Measurement of Percentage Transmission of White Light | aquatic life | Estimating percentage transmission of white light requires simultaneous measurements of light intensity at the surface and at a selected depth (generally below 1 m to avoid effects from surface agitation). | When evaluating apparent colour via transmission of white light | high |
| #Q007 | monitoring | reporting | recommended | 30-Day Mean Sampling Methodology (True Colour, Aquatic Life) | aquatic life | The 30-day mean calculation should be based on a minimum of five weekly samples taken over a period of 30 days. | When calculating the 30-day mean true colour for aquatic life | high |
| #Q008 | monitoring | operational | recommended | Preferred Analytical Methodology for True Colour | aquatic life | In situ single wavelength analysis at 456 nm with the results calibrated against the Hazen measurement scale is the preferred analytical methodology for true colour. | When analyzing samples for true colour criteria in aquatic life contexts | high |
| #Q009 | monitoring | reporting | recommended | Anthropogenic Impact Testing Procedure (Apparent Colour, Aquatic Life) | aquatic life | Therefore, when testing whether a particular anthropogenic activity has caused an increase in apparent colour above the water quality criterion, several samples (n greater than or equal to 5) should be taken over a 30-day period and a mean calculated (or median if the data are right skewed). | When evaluating anthropogenic impacts on apparent colour | high |
| #Q010 | monitoring | reporting | recommended | Anthropogenic Impact Testing Procedure (True Colour, Aquatic Life) | aquatic life | Therefore, when testing whether a particular anthropogenic activity has caused an increase in true colour above the water quality criterion, five weekly samples should be taken over a 30day period and a mean calculated (or median if the data are right skewed). | When evaluating anthropogenic impacts on true colour | high |
| #Q011 | monitoring | reporting | recommended | 30-Day Mean Sampling Methodology (Apparent Colour, Wildlife) | other | The 30-day mean calculation should be based on a minimum of five weekly samples taken over a period of 30 days. | When calculating the 30-day mean transmission of white light for wildlife protection | high |
| #Q012 | monitoring | reporting | recommended | 30-Day Mean Sampling Methodology (True Colour, Wildlife) | other | The 30-day mean calculation should be based on a minimum of five weekly samples taken over a period of 30 days. | When calculating the 30-day mean true colour for wildlife protection | high |
| #Q013 | monitoring | reporting | recommended | 30-Day Mean Sampling Methodology (Apparent Colour, Recreation) | recreational water | The 30-day mean calculation should be based on a minimum of five weekly samples taken over a period of 30 days. | When calculating the 30-day mean Secchi disk sighting range for recreation | high |
| #Q014 | monitoring | reporting | recommended | 30-Day Mean Sampling Methodology (True Colour, Recreation) | recreational water | The 30-day mean calculation should be based on a minimum of five weekly samples taken over a period of 30 days. | When calculating the 30-day mean true colour for recreation | high |
| #Q015 | monitoring | reporting | recommended | Anthropogenic Impact Testing Procedure (Colour, Recreation) | recreational water | Therefore, when testing whether a particular anthropogenic activity has caused an increase in colour above the water quality criteria, five weekly samples should be taken over a 30-day period and a mean calculated (or median if the data are right skewed). | When evaluating anthropogenic impacts on true and apparent colour in recreational waters | high |
| Req ID | Category | Intent | Legal Status | Name | Subdomain(s) | Limit Type | Limit Value | Context | Conditions | Confidence |
|---|---|---|---|---|---|---|---|---|---|---|
| #P001 | physical | aesthetic | guideline | True Colour | drinking water | AO | 15 mg/L Pt | The aesthetic water quality criterion for true colour is 15 mg/L Pt. | Applies to systems in which background colour is less than 15 mg/L Pt and the water does not require treatment beyond disinfection. | high |
| #P002 | physical | unknown | guideline | Apparent Colour | aquatic life | requirement | <= 80 % | The 30-day mean transmission of white light shall be less than or equal to 80% of background levels as measured historically or at appropriate reference sites. | Applies to freshwater, estuarine and marine aquatic systems. | high |
| #P003 | physical | unknown | guideline | True Colour | aquatic life | requirement | <= 5 mg/L Pt | The 30-day mean true colour of filtered water samples shall not exceed background levels by more than 5 mg/L Pt or (> 5 true colour units) in clearwater systems. | Applies to clearwater systems (background levels <= 20 mg/L Pt) in freshwater, estuarine and marine aquatic systems. | high |
| #P004 | physical | unknown | guideline | True Colour | aquatic life | requirement | <= 20 % | The 30-day mean true colour of filtered water samples shall not exceed background levels by more than 20% in coloured systems. | Applies to coloured systems (background levels > 20 mg/L Pt) in freshwater, estuarine and marine aquatic systems. | high |
| #P005 | physical | unknown | guideline | Apparent Colour | other | requirement | >= 80 % | 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. | Applies to wildlife in freshwater, estuarine and marine aquatic systems. | high |
| #P006 | physical | unknown | guideline | True Colour | other | requirement | <= 5 mg/L Pt | 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. | Applies to wildlife in clearwater systems (background levels <= 20 mg/L Pt). | high |
| #P007 | physical | unknown | guideline | True Colour | other | requirement | <= 20 % | The 30-day mean true colour of filtered water samples shall not exceed background levels by more than 20% in coloured systems. | Applies to wildlife in coloured systems (background levels > 20 mg/L Pt). | high |
| #P008 | physical | aesthetic | guideline | Apparent Colour | recreational water | requirement | >= 1.5 m | The 30-day mean Secchi disk sighting range should be greater than or equal to 1.5 m. | Applies to recreation and aesthetics in freshwater, estuarine and marine aquatic systems. | high |
| #P009 | physical | aesthetic | guideline | True Colour | recreational water | requirement | <= 15 mg/L Pt | The 30-day mean true colour of water should be less than or equal to 15 mg/L Pt (i.e., blue to green water). | Applies to recreation and aesthetics in freshwater, estuarine and marine aquatic systems. | high |
| #P010 | physical | unknown | guideline | Apparent Colour (Secchi disk sighting range for diving) | recreational water | requirement | >= 4 m | More stringent site-specific ambient criteria will be required for recreational waters used for diving. | Applies to recreational waters used for diving. | high |
| Req ID | Category | Name | Context | Confidence |
|---|---|---|---|---|
| #D001 | apparent colour | Colour measured in water containing suspended matter | high | |
| #D002 | Hue | whether the water colour is described as blue, green or yellow, for example, and is determined by the dominant wavelength in the visible spectrum | high | |
| #D003 | euphotic zone | the zone with sufficient light to support photosynthesis, generally one percent of ambient light | medium | |
| #D004 | spectral purity | the ratio of the line C-S to the line L-S | high | |
| #D005 | extinction coefficient | a constant that predicts the attenuation or dissipation of light at a certain wavelength. | high | |
| #D006 | Brightness | depends on the amount of energy detected by the human eye, which is most sensitive to green light of wavelength 555 nm. | high | |
| #D007 | Saturation | depends on the spread of energy around the dominant wavelength. | high | |
| #D008 | True colour | is due to natural minerals such as ferric hydroxide and dissolved organic substances such as humic or fulvic acids. | high | |
| #D009 | Secchi disk transparency | the mean depth of the point where a weighted white disk, 20 cm in diameter, disappears when viewed from the shaded side of a vessel during mid-day, and the point where it reappears upon raising it after being lowered beyond visibility. | high | |
| #D010 | Munsell value | a measure of apparent brightness and ranges from 0 (black) to 10 (white). | high | |
| #D011 | Munsell chroma | related to colour saturation (or spectral purity) and extends from 0 for neutral grays to values of 20 or more for the most saturated colours. | high | |
| #D012 | dominant wavelength | the colourimetric definition of colour in the water body. | high | |
| #D013 | Beer-Lambert's Law | the light intensity or irradiance at a particular depth ( I z ) is a function of the intensity at the surface ( I o ) to the exponent of the negative extinction coefficient at the depth distance z | high | |
| #D014 | derivative spectroscopy | records variations in the rate of change of absorbance ( A ) with wavelength. | high | |
| #D015 | Munsell hue (H) | Munsell hues are divided into 100 hue units and are designated as, for example, 10 BG indicating that the sample corresponds to the 10th unit of the blue-green hue range. | high | |
| #D016 | Fore-Ule colour scale | involves comparisons to alkaline solutions of cupric sulfate, potassium chromate and cobaltous sulfate. | high | |
| #D017 | tristimulus values | a system of parameters referred to as tristimulus values that can be calculated from up- and down-welling spectral irradiance data | high | |
| #D018 | Hazen units | the platinum concentration in mg/L is equivalent to the colour value in Hazen units | high | |
| #D019 | THMs | trihalomethanes | high | |
| #D020 | PAR | photosynthetically active radiation | high | |
| #D021 | white scattering centers | suspended particulates | medium | |
| #D022 | NTU | nephelometric turbidity units | high | |
| #D023 | TCU | true colour units | high | |
| #D024 | Munsell system of colour | A robust means of determining in situ apparent colour | high | |
| #D025 | tristimulus colour system | based on a system of parameters referred to as tristimulus values that can be calculated from up- and down-welling spectral irradiance data | high | |
| #D026 | achromatic point S | For a white spectrum, X = Y = Z = 0.333. This defines the achromatic point S. | high | |
| #D027 | chromaticity envelope | The loci of all possible (Z,Y) pairs define an envelope which encompasses all possible chromaticity values. | high | |
| #D028 | TCMTB | anti-sapstains | high |