Snapshot of Sediment in Local Creeks

August08

Snapshot of Sediment in Local Creeks

Last Tuesday, after the high flow event in Holbrook, HLN got out to check on some of the local creeks and streams. Using a turbidity tube, we took a snapshot of sediment present in the creeks, which can tell a lot about the health of the creek and the catchment.

Turbidity is the cloudiness/haziness of the water which is caused by small particles of sediment. The simple measurement is a great way to see how much sediment is present, and which creeks may have erosion issues further upstream.

Turbidity measure of small (unnamed) stream along Jingellic Road. This was the clearest stream measure, with little sediment moving down the stream and a turbidity measure of 45 NTU

Turbidity measure of small (unnamed) stream along Jingellic Road. This was the clearest stream measure, with little sediment present and a turbidity measure of 45 NTU.

 

Creeks and streams with a high turbidity measure indicates it is carrying sediment that has eroded further up the catchment. Excess sediment degrades waterways and has a major impact on the aquatic environment by blocking light and changing plant growth conditions, which in turn has an effect on aquatic life. Water quality is also affected by pollutants such as nutrients, heavy metals and microbes. These are nutrients from your paddocks running into nearby waterways where they can cause algal blooms.

The erosion site, where the sediment is coming from, can cause another set of issues on farm including loss of productive land and reduced access.

Below is a great example of a creek in Holbrook carrying a high sediment load. It had a high turbidity measure, with quite large sediment particles. Sediment can come from the erosion in the catchment upstream, from the stream channel itself and be sediment that has eroded before but is re-mobilised after being stored in the system itself.  To see what is causing this you need to look further up the catchment, where it is assumed that there is an active gully or stream erosion that has scoured in the recent rain, contributing high levels of sediment to the stream.

 

 

This creek is carrying a high sediment load. The water is very sloudy and has a turbidity measure of approx. 420 NTU.

Wantagong 6

This creek is carrying a high sediment load. The water is very cloudy and has a turbidity measure of approx. 420 NTU.

 

So, what can you do?

Now is a great time to get out and have a look at the waterways on your property. Watch where the water is moving and what level of sediment it contains.

The best way to slow down the water and improve the soil ability to absorb the water is to increase groundcover. By managing groundcover effectively, you improve your risk of erosion and losing soil to waterways.

If you do notice erosion nicks, address them early before they become a bigger issue. Small erosion sites may be remediated by removing livestock, fencing off, improving vegetation or building low-cost erosion structures. If the erosion site is already large and established then call the NSW Soil Conservation Service for expert, technical advice.

 

 

 

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