Water salinity changes in the Lower Murray River
Prior to the current “drought” water salinities in the lower Murray River upstream of Wellington were usually below 500 mg/L or an electrical conductivity of 800 EC units. During periods of flood, salinities and hence conductivities were much less.
The conductivity of water in Lake Alexandrina was in the order of 1500 EC units.
In the last 2 years water conductivities in Lake Alexandrina have risen to 5000 - 6000 and water levels have declined to 1m below sea level as a result of low river flows and evaporation.
The flow below lock 1 at Blanchtown has been maintained at a minimum level of 1GL/day partly to prevent this saline Lake Water from moving upstream. This has been successful until recently when the combination of low water levels and strong southerly winds pushed the saline water upstream .
The graph below showing the conductivities over time at Wood Point (between Tailem Bend and Murray Bridge) shows dramatically the result of this saline incursion with conductivities rising from 600 to 800 prior to June this year to over 2000 EC at times. Click here for a pdf of the graph below. It comes from this website http://data.rivermurray.sa.gov.au/Plot.aspx?Param=A4261126&Period=Hrly .