Organic pollution in farm dams
Remove organic material from the water as soon as possible, as it usually saturates and sinks within 48 hours. Skimming the surface of the water is the most effective method.
A system to rapidly remove floating organic matter has been developed by farmers in Western Australia and was updated by Agriculture Victoria in 2020, it skims floating material from the water surface using a handheld boom. The boom has floats attached on both sides of the top edge at regular intervals (every metre or so).
- Thread a cable, nylon rope or wire along the top and bottom edge of 30 m long × 45 cm wide length of linkmesh or chicken wire/rabbit netting (See Figure 1) Loop the rope occasionally on the mesh or fix it with cable ties etc to help prevent mesh from sliding along the rope when under load. Allow 5–10 m of rope/cord to extend beyond the mesh to allow for handling.
- Attach floats every metre or so along the mesh about 10 cm from the top edge. Floats can be empty drums or milk containers, with electrical cable ties or wire used to attach floats to the mesh.
- Slowly drag the boom across the surface by hand or by attaching to a quad bike. Anchoring one end of the boom will assist if there are few people to assist with the operation.
- Scoop small amounts of the water surface at a time, moving the boom slowly to the edge. When the mesh if full of debris, it will be very heavy to manoeuvre. Working towards a gently sloping bank will make operation easier. Empty debris over the side or into the spillway away from inflows.
- Repeat the process until the dam is clear of debris.