As part of the Community-based Water Monitoring project, the Elk River Alliance has been monitoring dissolved oxygen (DO) levels at 8 sites in the Elk Valley since 2011 (4 sites on Lizard Creek) and 2012 (4 sites on Alexander Creek). This has included high and low flow monitoring (June/October respectively) at each of the 8 sites and more recently, monthly monitoring on Alexander Creek.
As shown in the chart, the minimum DO levels are 9 mg/L and 8 mg/L for Lizard and Alexander Creeks (respectively); the maximum DO levels are 15 mg/L and 13 mg/L for Lizard and Alexander Creeks (respectively); and, the average DO levels are 11.3 mg/L and 11 mg/L for Lizard and Alexander Creeks (respectively).
For more information on dissolved oxygen and why it is important, keep reading below!
Dissolved oxygen is the amount of oxygen in the water available to aquatic organisms. This is what fish and invertebrates breathe using their gills. The amount of dissolved oxygen present in the water is directly affected by stream temperature, and colder water can hold more DO (why?). Oxygen is dissolved into water in 3 ways: by aeration (i.e. mixing over rapids), diffusion from surrounding air and from aquatic plants.
The concentration of dissolved oxygen is measured in milligrams per litre, in the case of water, this is an equivalent measurement to parts per million (ppm). Therefore, for a concentration of 10mg/L=10 ppm, for every million parts of water, there are 10 parts of oxygen. The BC Ministry of Environment recommended guidelines for DO are instantaneous minimums of 5 mg/L for most life stages and 9 mg/L for buried embryo/alevin (i.e. baby fish); and, 30 day average minimums of 8 mg/L for most life stages and 11 mg/L for buried embryo/alevin.