Water Resource Recovery Catchments
The 1996 Salinity Action Plan designated portions of key water supply catchments effected by salinity as Water Resource Recovery Catchments (WRRCs).
The catchments are:
- Helena River
- Collie River
- Warren River
- Kent River
- Denmark River
Salinity Situation Statements were completed for all five catchments. Their purpose was to analyse where and why the salinity of the rivers became marginal or brackish and state the current salinity situation of the catchment with respect to land-use changes, groundwater and surface water. They proposed management options to achieve fresh water (≤ 500 mg/L) at their outlets.
The Helena WRRC is sometimes referred to as the Mundaring Catchment. Water from the Helena Reservoir is used to supply water to the Goldfields and the Agricultural region. The salinity of the inflows to the reservoir is mostly in the fresh category, but sometimes the limit is exceeded and water is then diluted by supplemented fresher water from the Integrated Water Supply Scheme. The catchment is currently only 3% cleared but, if all the free/leasehold land in 1978 was cleared, then the salinity would likely rise from 500 mg/L to 1500 mg/L. Clearing controls have prevented the salinity of the river from increasing significantly.
The Department of Water won the Australian Business Award Sustainability category 2013 and the Australian Water Association's 2014 National Research Innovation Award for its work on returning the Denmark River's water 'from brackish to drinkable'. The water now has a salinity of 540 mg/L and is currently used as a back-up water supply for the Denmark Town. The Denmark River water resource recovery plan (2011) outlines the salinity recovery options available for the Denmark WRRC. Science and modelling was used to evaluate the options. Revegetation of cleared farmland to blue gums, buy back of farmland and subsequent revegetation in 1984 and fencing of remnant vegetation were integral to the recovery of this water resource.
The Collie WRRC includes the Wellington Reservoir, which is a potentially valuable water supply for the State. The Harris Reservoir was built in 1989 to replace the Wellington Reservoir as the source for the Great Southern Towns Water Supply scheme as the reservoir had become too salty. The salinity of the reservoir is currently 1000 mg/L and is used for irrigation and recreation. Salinity of water flowing into the Wellington Reservoir has stabilised due to clearing controls enacted in the mid 1970s, as well as planting of pine and blue gum plantations in the Wellington Plantings Estate. The Wellington Plantings Estate is 18 350 ha of land owned and managed by the Department consisting of native vegetation, mixed eucalypt plantings and some plantation plantings. This land was farmland that was bought back and revegetated by the Government to reduce salinity in the reservoir.
The Kent and Warren WRRC salinity levels are currently around 1300 mg/L and 1000 mg/L respectively. Feasible options to reduce the inflow salinity of the Collie, Kent and Warren WRRCs have been developed, but no action is planned at this time.
Helena River (2005)
Photograph by Renee Dixon.
Salinity Situation Statements for the WRRCs: