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

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River Murray and Lower Lakes catchment risk assessment for water quality: Results and management options The water quality of Lakes Alexandrina and Albert has been noted in the past as being poor (EPA 1998a, b) as a result of: • high turbidity in Lake Alexandrina (influenced by wind action readily suspending sediment in the shallow water depth) • moderate nitrogen and phosphorus concentrations • concentrations of heavy metals exceeding national guidelines for the protection of aquatic ecosystems at some sites • salinity exceeding the guidelines for good quality drinking water at some sites • pollutant inputs from rivers (eg Angas, Bremer, Murray). Although detailed load information was not obtained, it was assumed that pollutant loads from the River Murray itself were the biggest influence on water quality in the Lower Lakes. The River Murray was not specifically assessed as a hazard in this chapter; its risks have been assessed separately in previous chapters of this report. Other creeks and rivers were assessed as point source hazards as a detailed catchment risk assessment was outside the scope of this stage of the study. The first recorded incidence in Australia of animal poisoning from a blue-green algal bloom was in Lake Alexandrina, in the late 1800s. Cattle, horses, pigs, sheep and dogs died after drinking water covered by a scum of the blue-green alga Nodularia spumigena. Algal blooms in the lake since then(Codd et al 1994) include a recent Nodularia sp outbreak. Salinity reduces the Coorong’s water quality: reduced tidal flushing and freshwater inputs (Gell & Haynes 2005) lead to prolonged hyper-saline conditions in the southern lagoon (DWLBC 2005) where salinity levels are often elevated above the tolerance of many aquatic species. The southern lagoon is now almost devoid of macrofauna (Dittman et al 2006). The USE Dryland Salinity and Flood Management Program releases are having a freshening effect on salinity of the Coorong near the mouth of Salt Creek (DWLBC 2005). 7.2 Environmental value zones Spatial zones assigned for each environmental value allowed hazards to be identified and assessed for risk in manageable amounts. Aquatic ecosystem zones Risks to aquatic ecosystem health were assessed for the entire Lower Lakes and Coorong area. Raw water supply zones There are no large public raw water supply off-takes in the Lower Lakes and Coorong area so risks to this environmental value were not assessed in this report. Municipal water supplies for this area are sourced from the Myponga, Summit Storage and Tailem Bend water supply systems. Assessment of the private and other small supplies on the Lower Lakes was considered outside the scope of this stage of the study. Recreational zones Nine recreational zones were identified in the GW & CD LAP areas: RWREC001 Goolwa and surrounds (8 km long) RWREC002 Number 19 beacon to Murray mouth (5.36 km long) RWREC003 Mundoo channel (& Holmes Creek) to Coorong channel (8.5 km long) 194
River Murray and Lower Lakes catchment risk assessment for water quality: Results and management options RWREC004 Clayton and surrounds (2.5 km long) RWREC005 Milang and surrounds (3.2 km long) RWREC006 Boggy Lake (5.5 km long) RWREC007 Meningie and surrounds (3.7 km long) RWREC008 Milang and surrounds (6.4 km long) RWREC009 Mark Point to Long Point (11.6 km long). 7.3 Hazard identification process A community consultation workshop was held with representatives from the Goolwa to Wellington and Coorong District LAP groups, Alexandrina and Coorong District councils, community groups (eg Signal Point riverine, Waterwatch), DWLBC, SAMDB NRMB, local marinas, Ngarrindjeri, EPA and private industry. The workshop identified the nature and location of potential water quality hazards and recreation zones, and provided useful information for the subsequent risk evaluation process. 7.4 Risks to water quality in the Goolwa Wellington and Coorong District LAP areas A total of 168 hazards were identified within the GW & CD LAP areas. The hazards with the highest frequencies were stormwater discharge points, toilets/septic tank systems, dairy farms, vessel launching/boat ramps, grazing (of riparian area) and wastewater infrastructure (Figure 7.3). Frequency (occurrence) does not necessarily indicate risk—a hazard may have a high frequency but a low risk. The cumulative impacts of low-risk activities will be considered and assessed as part of mitigation strategy development. Figure 7.2 Example of hazard to water quality in GW & CD LAP areas: Finniss River 195
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E N V I R O N M E N T P R O T E C T
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The River Murray and Lower Lakes ca
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6 Mannum to Wellington LAP area ass
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Table 6.5 Frequency of risk to recr
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Figure 7.2 Example of hazard to wat
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Roz Becker, Riverland Tourism Assoc
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Abbreviations 10 ADWG Australian Dr
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Executive Summary The River Murray
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River Murray and Lower Lakes catchm
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2 Renmark to border LAP area assessment - EPA - Sa.gov.au

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