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Saving Sediment in the LockyerThe Healthy Country project is trialling methods to reduce sediment loads entering waterways in three focal subcatchments. One of these focal areas is Blackfellow Creek, a tributary of Lockyer Creek.
 Work undertaken by the eWater CRC team lead by Professor Jon Olley from the Australian Rivers Institute at Griffith University has shown that 80% of the sediment exported from the focal area comes from the cropping lands located in the lower floodplain. Efforts to reduce soil surface erosion should thus focus on the cropping areas.
The scientific study and local landholder knowledge have been used by SEQ Catchments and the Local Committee to develop the Blackfellow Creek Action Plan. The Plan targets actions to reduce sediment export from the highest contributing areas. One of the types of actions being implemented by landholders on a number of horticulture properties in the Blackfellow Creek catchment is the use of sediment ponds together with drainage improvements.
The sediment ponds are proving a valuable tool for sediment control and are being incorporated into many property management plans. Effectively, they help to keep soil on the property preventing it being lost downstream or onto neighbouring properties.
Strategically located and properly constructed sediment traps offer a last line of defence for waterways. The traps come in a number of forms ranging from small depressions behind a leaky barrier to large excavations. Whatever the type, the objective is the same, i.e. to intercept overland flows, slowing velocity and thus allowing sediment to drop to the bottom before flows then enter a waterway.
Sediment ponds are being used as an effective part of an overall system for sediment control, including improvement of ground cover, wide flat-bottomed grassed drains which feed into ponds and well vegetated riparian areas. They are proving particularly useful in agriculture for sediment control where permanent groundcover is not feasible.
Over time, sediment ponds do require maintenance if they are working well. Trapped sediment can be respread back on the property. Established ponds can also provide wildlife habitat in modified landscapes.
Download the Sediment Ponds in Agriculture factsheet.
Image (Courtesy of SEQ Catchments): Sediment pond which intercepts flows from over 100 hectares before entering Blackfellow Creek, Lockyer Valley.
Article by Fiona Bengtsson
Healthy Country project coordinator, Lockyer
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