pH

One of the parameters that ERA measures during our community-based water monitoring on Lizard and Alexander Creek, as well as during our monthly monitoring on Alexander is pH. The pH of a substance measures the concentration of hydrogen atoms and describes how alkaline or acidic the substance is. This is measured using a scale from 0-14, with 0 being highly acidic, 14 being highly alkaline and 7 being neutral. Since the pH scale is logarithmic, each number is 10x more alkaline than the previous number (i.e. 8 is 10x more alkaline than 7).

Below is a chart summary of ERA's pH water quality data on Lizard and Alexander Creeks (4 sites on each stream... numbers 1-4 identify site).

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As shown in the chart above, the measured pH ranged from 8.3-8.9 for Lizard Creek and 8.4-8.7 for Alexander Creek. Both creeks have an average pH of ~8.6. To learn more about pH, continue reading below...  

One might expect that a healthy aquatic ecosystem would require a pH close to neutral (7.0); however, this is not necessarily the case. The pH of a stream has a lot to do with the surrounding geology. In the Elk Valley, there is so much limestone (which is alkaline) that most of the streams have a pH significantly higher than 7.0. This explains why both Lizard and Alexander Creek have a pH around 8.6. Also, since this is "normal" for the area, aquatic life is well adapted to this pH range.

The BC Ministry of Environment has deemed that a pH range from 6.5-9 is harmless to fish (see Technical Report). A pH of 9.0-9.5 however, is "likely to be harmful to salmonids... if present for a considerable length of time".

The true value of citizen science data is establishing long-term trends. Once trends are established, any significant deviation from the trend (i.e. in the case of a pH above 9.0 at one of the sites) would raise a red flag and trigger further investigation.  

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Elk River Alliance
a community-based water group that aims to connect people to the Elk River ensuring it is drinkable, fishable and swimmable for future generations.