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Table 4: Key impacts associated with water pollution from diffuse-source runoff
Sediment is released from eroding, disturbed soils associated with grazing and cropping. It causes turbidity, decreases light in the water column and reduces the extent and condition of the aquatic plant assemblage in both freshwater and marine systems (Serov et al, 2019). Freshwater tributaries with significant diffuse-source run-off inputs from agriculture include the Little Manning (high phosphorous); the Barnard River (high turbidity, phosphorous, nitrogen); the Bowman and Gloucester rivers (high nitrogen). Based on results in the Estuary Health Risk Model, nutrient and sediment risks in the estuary are highest in Cedar Party Creek and the Lansdowne River. Key impacts of agricultural diffuse-source run-off on catchment and estuary values are shown in Table 4 below.42
PRIORITY PROBLEM KEY IMPACTS TO ADDRESS
Sediment levels exceeding ANZECC Guidelines • smothering of aquatic ecosystems • increased water infrastructure maintenance costs
Nutrient levels levels exceeding ANZECC Guidelines
Pathogen levels levels exceeding ANZECC Guidelines • nuisance weed growth and harmful algalblooms • increased water treament cots • reduced fishery production (commercial and recreational) • reduced fishery production (acquaculture, commercial and recreational fishing • human health impacts from aquatic recreation
Table 4: Key impacts associated with water pollution from diffuse-source runoff.
Stakeholders include: Hunter Local Land Services’ DPIE Department of Agriculture, MidCoast Council, MidCoast Dairy Advancement Group, NSW Farmers Association, Young Farmers Network, Economic Development Council, Mid Coast 2 Tops Landcare. Related issues: loss and degradation of coastal wetlands and riparian vegetation; floodplain drainage and ASS.
42: NSW Government, 2009
