Surface water quality

There is no long-term, consistently applied water quality monitoring program in the Gloucester subregion. Therefore there is limited capacity to fully understand what baseline water quality should be for the subregion. The data provided in the text has limited capacity to be used with confidence to indicate the baseline water quality for the river systems mentioned.

Surface water quality measurements in the northern part of Gloucester subregion have been mainly conducted in the Avon River and its tributaries. The salinity (electrical conductivity; EC) and acidity (pH) of the Avon River, Avondale Creek and Dog Trap Creek were intermittently measured between 1993 and 2009 (SRK, 2010). Measured ECs vary from 100 to 500 µS/cm and pH is near neutral to slightly alkaline. The EC is also well related with rainfall, with a reduction in EC following rainfall and an increase in EC when flow reduces and baseflow increases.

Another surface water sampling program was undertaken in April 2011 at three monitoring locations on the Avon River (Parsons Brinckerhoff, 2012). Salinity at the time of sampling was fresh with EC varying from 161 to 324 µS/cm and showing a slight increase in a downstream direction. The pH for the three sampling locations is near neutral, with a pH value varying from 6.6 to 7.4. It is noted that there were regular flows in April 2011 which would have kept the conductivity readings down.

Surface water samplings for the southern part of Gloucester subregion were intermittently undertaken by Gloucester Coal Ltd on Karuah River and Mammy Johnsons Rivers in 2002 to 2009 (Gilbert and Associates, 2010). Measured salinity is less than 600 µS/cm for the Mammy Johnsons River, and is less than 400 µS/cm for the Karuah River; pH for both rivers shows large variation, varying from 6.3 to 8.5.

The pH and EC readings for gauge 209003 on the Karuah River at Booral were also kept by NSW Office of Water. Between 2007 and 2013, pH ranged from 6.3 to 7.6 and EC ranged from 96 to 346 µS/cm.

Last updated:
5 January 2018