2 Renmark to border LAP area assessment - EPA - Sa.gov.au

River Murray and Lower Lakes catchment risk assessment for water quality: Results and management options
Risks to raw water supplies
Figure 4.4 is the key map for risks to the raw water supply environmental value in the RW LAP area. The
attached CD has individual maps numbered according to the key map.
Frequencies of identified risks to raw water supplies for the various water quality parameters are
summarised in Table 4.3. The highest frequency of risks was for nutrients, followed by organic matter,
pathogens, hydrocarbons, salinity, turbidity, heavy metals and pesticides. Most of these risks were rated
as low (162) level, with only a few (6) moderate risks.
Table 4.3 Frequency of risks to raw water supplies, RW LAP area
PA—pathogens; NU—nutrients; TU—turbidity; OR—organic matter; HM—heavy metals; PE—pesticides;
HY—hydrocarbons; SA—salinity
The raw water supply risks identified in this LAP area are listed in Table 4.4 land discussed in more detail
below for each stressor.
Pathogens
Waste disposal systems (Cadell shacks, Waikerie riverfront septic tanks, Blanchetown township), a vessel
mooring area just upstream of Blanchetown bridge, and accidental spillage from the Blanchetown river
vessel waste disposal were assessed as moderate pathogen risks. The distance from the Blanchetown
hazards to the off-take is reasonably large (>350 m) but effluent from the vessel station and adjoining
public toilets is pumped up above the cliff line to a large soakage trench located 50 m inland from the
cliff edge and pumped out every 6–12 months. There are plans to move it further inland and possibly
establish a wastewater reuse scheme.
Jaeschke lagoon (opposite Waikerie off-take) was assessed as a moderate risk—animals graze all around
the lagoon and upstream of the ferry. Informal camping at Morgan Conservation Park (opposite Morgan
off-take) was assessed as a moderate pathogen risk. Cadell Training Centre lagoon (degraded wetland
affected by grazing) was also classed as a moderate risk (Cadell Training Centre unfiltered off-take).
Low risk sources of pathogens included ferry runoff (Waikerie and Cadell) and accidental spillage from
the River Murray Queen. Double reinforced pipes pump waste inland from this vessel so a low risk was
assigned. Stormwater discharge from the McCutcheon Street catchment in Waikerie was classified as a
low pathogen risk as it is over one kilometre upstream from the off-take.
100
Stressor
Risk PA NU TU OR HM PE HY SA Total
Low 18 20 6 19 4 1 16 9 93
Mod 2 2 0 2 0 0 0 0 6
High 0 0 0 0 0 0 0 0 0
V high 0 0 0 0 0 0 0 0 0
Total 20 22 6 21 4 1 16 9 99