Sources of toxicants to wetlands:

• Pesticide and heavy metal toxicants enter wetlands from diffuse catchment via local overland surface flow, in floodwaters or directly from urban, mining and agricultural land use or point sources.
• Oil toxicants generally enter wetlands from cars, roads, parking lots, washdown facilities, other urban sources or boat engines.
• Toxicant spills are rare but can dump large amounts of toxic material at a time into a wetland.
• Toxicants can enter wetlands via direct application of insecticides (e.g. mosquito control) or herbicides (e.g. aquatic weed control).