Table 2: Subcatchments posing the highest risk to ecological and community values

5.1.2 Results

A summary of high risk subcatchments is provided in Table 2. Targeted on-ground works in these subcatchments will have the best chance of improving the health of the Manning estuary by mitigating threats using a holistic approach. The highest risk of impacts from nutrient and sediment inputs, acidic runoff from acid sulfate soil, and pathogen inputs from stock on ecological and community values of the Manning estuary comes from the Lansdowne River catchment.

Risk Assessment High risk subcatchments

Estuary Health Risk Lansdowne River (88, 223), Cedar Party Creek (95) (Figure 22)

Stock pathogen risk on drinking water quality

Stock pathogen risk on Aquaculture

Erosion risk impacting riparian vegetation Dingo Creek (86), Manning River (99, 105), Barrington River (117), Gloucester River (98, 122)

Oxley Island (203), Mamboo Island (204), Jones Island (205), Lansdowne River (88,223) Cattai Creek (93)

Manning River (105,110), Upper Manning River (92, 96), Myall Creek (76), Barnard River (82)

Acidic runoff Lansdowne River (88, 223), Cattai Creek (93)

Table 2: Subcatchments posing the highest risk to ecological and community values

NB: The numbers in brackets (Table 2) relate to numeric identifier codes used for drainage units within each subcatchment there are 88 numbered drainage units in the catchment. There is considerable variation between within individual subcatchments, meaning the results cannot necessarily be applied to an entire subcatchment but should be used as a guide to further field investigations.

Figure 22 shows the Estuary Health Risk Map. Subcatchments in red pose the highest risk of sediment and nutrient loading into the estuary.