Turbidity is a measure of cloudiness of water (it indicates how much light can pass through). When turbidity is low, the water is clear; when turbidity is high, the water is opaque. Through ERA's community-based water monitoring program, turbidity is measured during monthly monitoring at Alexander Creek as well as at high and low flow monitoring on both Alexander and Lizard Creeks.
In the chart above, turbidity is measured in JTUs (Jackson Turbidity Units) and NTUs (Nephelometer Turbidity Units), which both measure how light travels through a water column and are approximately equivalent measurements. As shown above, turbidity measurements range from 0-25 on Lizard Creek (average 5.2) and 0-30 on Alexander Creek (average 5.3). As expected, turbidity increases greatly during high flow and water is usually very clear at low flow. It is interesting to note the turbidity spike at site 1 on Lizard Creek during 2014 flow, as this may correlate with upstream trail work happening below Mt Fernie Provincial Park.
To learn more about turbidity and why it's important, keep reading!
Turbidity is an important measure of water quality. It is typical for turbidity to be high during peak flows due to the increased amount of precipitation and runoff. However, turbidity is also increased due to land disturbance (such as logging) especially when it occurs close to the stream and/or on slopes. Turbidity can negatively affect aquatic ecosystem health, especially when it occurs over a prolonged period of time. If turbidity is high, When there is a lot of sediment in the water (i.e. high turbidity), it settles out on the bottom of the stream and fills in 'interstitial spaces', which are the spaces between rocks on the bottom of the stream. These spaces are home to most aquatic invertebrates so when they are filled in, the invertebrates (who are food for fish) die. Sediment can also settle out of the water column and smother fish eggs.
The best ways to reduce turbidity in the water are to leave a substantial vegetation buffer between logging/development and to avoid eroding stream banks (i.e. fencing livestock, keeping motorized vehicles out of the stream, etc).