The different incident types affecting inland waters have been grouped into logical categories as shown in the figure below. The water pollution/contaminated discharges group includes contaminated stormwater, discolouration/foam and scums, other contaminant discharges, oil and diesel spills, other water pollution and spraydrift. While diversion and drainage work, water abstraction and flooding hazard and erosion incidents have been grouped, as they are all related to water quantity and/or flow rates. Incident types where one of the main concerns is bacteriological contamination and associated human health risks have been grouped, which includes sewage, dead stock, dead or dying organisms and farm dairy effluent incidents.
The greatest proportion of the inland water incidents were related to contamination of waterways with 41% in the water pollution group and 24% in the Sewage/FDE/dead stock group. The total number of incidents affecting inland waters in 2005-06 was 252, which is slightly more than the pervious year, where 222 inland water incidents were reported to the Council.