Clean Streams Consultants was contacted by a property owner with concerns regarding their private pond, with reports of discoloured and foul-smelling water. Clean Streams were asked to investigate the current state of the pond and examine what could be causing the issues with the system.
An ecological assessment was undertaken on the pond and adjoining wetland to establish any environmental parameters which may be adversely effecting the ponds water quality and creating the conditions the owner was concerned about. The assessment established that there was a significant amount of sediment being deposited within the pond. This increase of sediment was leading to succession of the pond . Rank grass was growing over the pond which further contributed to the sedimentation. The wetland was largely composed of Raupo (Typha angustifolia) with a mixture of native and non-native rushes and sedges occurring on the periphery. Organic oils were encountered in high occurrence on the water surface and a strong sulphurous smell was present when probing the sediment depth, indicating a high level of anoxic decomposition. It was suggested that the additional sediment was entering the system from the neighbour’s grazed pasture. The lack of root binding on the pasture and the gradient was the most probable cause of this sedimentation.
To address the issues, it was recommended to remove the additional sediment that had deposited within the pond. The pond provided an ideal habitat for both longfin eel (Anguilla dieffenbachii) and shortfin eel (Anguilla australis) and it would be preferable not to lose this valuable habitat to succession. To address the rank grass and non-native plants, a weed management program would be devised. Restoration planting along the edge of the pond would be undertaken, which would aid in capturing sediment and reducing deposition. Before any sediment removal is undertaken a fish recovery program will be undertaken.