Wetland conservation can occur in the revitalisation of a muddy farm dam or by protecting an existing wet area by fencing it off or through time controlled grazing. Or both. Wetlands can have very high biodiversity and therefore great potential to be important habitat. A well vegetated wetland can keep water quality high by both reducing sediment loads into waterways through slowing down runoff speed assisting flocculation (the drop out of heavier particles from the water column) and through removing excess nutrient as part of the growth and development of the plant. This is why constructed wetlands are now an important part of the waste management systems for nurseries, as well as tertiary water quality treatment in sewerage treatment works.