Prior to vegetation clearing for agriculture, salinity was recorded as approximately 120–350 mg/L, where <500 mg/L is considered fresh. The Wilgarup, Dombakup and Lefroy sub-catchments were initially cleared around 1925 as part of the
Group Settlement Scheme. Extensive clearing in the 1950s and 1960s resulted in a significant increase in stream salinity, with water quality no longer considered fresh. The Warren catchment was declared a clearing control catchment in 1978 following concerns with rising salinity levels. Following this declaration, intensive revegetation was undertaken within the Perup and Tone River sub-catchments, which account for 60% of the salt load entering the Warren River. Salinity levels are leveling off and clearing within the total catchment is now estimated as 35%. The lower Warren River to the river mouth is considered slightly brackish, with a mean annual salinity of 990 mg/L for the period 1993-2002, measured at Barker Road gauging station. Dombakup Brook is recorded as being fresh (< 440 mg/L). ==References==