F&G calls for heightened regulation of winter cropping activities in Otago

Fish & Game has called on the Otago Regional Council (ORC) to ramp up its monitoring and compliance to address sedimentation in streams resulting from winter cropping activities.

Otago Fish & Game has funded several University studies in an effort to build a picture of the impact of land use intensification on waterways in South Otago. A recent scientific paper from the University of Otago on the health of South Otago streams indicates that winter cropping practices such as strip grazing of stock, with insufficient riparian buffers or on land which is too steep, is a major contributor to in-stream sediment.

Significant rain events during winter months result in overland sediment laden run off entering waterways. Because most of the sediment run-off from crop paddocks occurs during these events, impacts are difficult to monitor and regulate and are often missed by routine water quality monitoring.

Otago Fish & Game Officer Morgan Trotter says “Sediment is a major stressor of stream life, it smothers invertebrate habitat and fish eggs and the data shows sediment levels in many South Otago streams are too high resulting in degraded aquatic ecosystems and fisheries”.

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Winter cropping on steep paddocks is a particularly high risk activity. Winter cropping without a sediment control measure in place is considered a prohibited activity, however what constitutes an acceptable control measure is not well defined.

According to Trotter “the priority should be to stop overland sediment runoff to waterways occurring in the first place. Until this is achieved we will not see meaningful improvement in water quality and stream health. The ORC should give firm advice on what is required to stop sediment run-off and back this up with strong regulatory action where required.

Trotter added that, in some steep hill country sediment loss cannot be captured without exceptional mitigation efforts and therefore “this type of land is unsuitable for winter cropping”.

Image credit - Fish &  Game