23.11.2012 Views

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

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

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

SHOW MORE
SHOW LESS

You also want an ePaper? Increase the reach of your titles

YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.

River Murray and Lower Lakes catchment risk <strong>assessment</strong> for water quality: Results and management options<br />

Highland irrigation practices also increase saline groundwater flows <strong>to</strong> the river in some horticultural<br />

<strong>area</strong>s (eg Mypolonga, DWLBC 2003a) posing a moderate risk.<br />

Turbidity<br />

Event discharges from the LMRIA were ranked as a moderate turbidity risk as in large rainfall events, the<br />

significant runoff from highland agricultural <strong>area</strong>s contains high levels of suspended material. Regular<br />

discharges were given a low risk ranking, as they are typically less turbid than the ambient river<br />

concentrations (although they may contain high colour and the pump outflow itself may disturb sediment<br />

in the river). Most other risks were classified as low but moderate risks with a potential cumulative<br />

effect are Mannum, Murray Bridge (including Rocky Gully wetland) and Tailem Bend s<strong>to</strong>rmwater<br />

discharges. Three of the five Tailem Bend s<strong>to</strong>rmwater discharge points have gross pollutant traps fitted.<br />

Hydrocarbons<br />

Several moderate hydrocarbon risks were identified including unbunded diesel irrigation pumps and fuel<br />

s<strong>to</strong>res on the edge of the river, urban s<strong>to</strong>rmwater discharges and transport infrastructure. The likelihood<br />

of accidental spillage from fuel s<strong>to</strong>res and bridges is low but the potential consequences resulted in a<br />

moderate risk <strong>to</strong> aquatic ecosystem health.<br />

The hydrocarbon risk from several Tailem Bend petrol stations located close <strong>to</strong> the River Murray was<br />

classified as low. They pose a risk of accidental spillage in<strong>to</strong> the s<strong>to</strong>rmwater system and underground<br />

leakage from fuel s<strong>to</strong>rage tanks. Other low hydrocarbon risks identified were from potential accidental<br />

spillage from recreational rivercraft and ferries.<br />

Heavy metals<br />

The number of risks attributed <strong>to</strong> heavy metals is few, primarily from urban s<strong>to</strong>rmwater discharges,<br />

which contribute significant amounts of heavy metals (eg lead, copper, zinc) during rainfall events.<br />

These metals are likely <strong>to</strong> be mostly in particulate form (therefore not immediately bioavailable or<br />

<strong>to</strong>xic) and may be accumulating around s<strong>to</strong>rmwater outfalls. The effect of this potential accumulation on<br />

benthic (bot<strong>to</strong>m-dwelling) aquatic biota is unknown.<br />

The current landfill at Mannum and the disused landfill pond at Sturt reserve (Murray Bridge) were also<br />

considered <strong>to</strong> pose a moderate heavy metal risk, as were the slipways at Mannum, and Long Island and<br />

Riverglen marinas (wash-off of metal materials, including metal-containing anti-fouling paints).<br />

An arsenic plume under the old railway yards Tailem Bend was assessed as a moderate risk. Moni<strong>to</strong>ring<br />

data indicates the plume is currently not leaching <strong>to</strong> the river.<br />

Pesticides<br />

All pesticide risks were assessed as low with the exception of the slipways at Mannum, and Long Island<br />

and Riverglen marinas. Wash-off from the slipway is likely <strong>to</strong> contain anti-fouling compounds although<br />

there was high degree of uncertainty <strong>to</strong> this <strong>assessment</strong>. The river water quality data indicates that<br />

pesticides levels were mostly below detection limits (SA Water unpublished data) which supports the<br />

current <strong>assessment</strong> of no high and widespread pesticide risks.<br />

160

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!