Overseer use in Rotorua Lakes

Overseer is an online tool to understand nutrient movement across agricultural landscapes, and the effect of farm practices on nutrient losses.

BOPRC sought to understand whether Overseer would be an appropriate regulatory tool for developing nutrient management plans, considering specific landscape features and biophysical conditions of the catchment, such as slope, drainage, and land use.

Through A2E, expert support involved an initial meeting and a review of existing data, literature and resources around the use of Overseer in areas like the Lake Rotorua groundwater catchment.

The report identified that for the catchment:

• Pastoral systems are dominated by dairying and dry stock systems.
• Approximately 99% of dairy land and 98.5% of dry stock land are on well drained soils.
• Most of the land within the catchment lies on land with low slopes.
• Nitrate-nitrogen is the key contaminant of concern.

Overseer performs better for pastoral systems on well-drained soils on flat to rolling land, where overland flow is minimal. It also performs best where nitrate-nitrogen is the primary type of leaching.

Findings from the report were presented on with an opportunity for BOPRC to discuss and give feedback.

The final report outlined the suitability of using Overseer for the Lake Rotorua groundwater catchment. With recommendations around the features that should be considered, BOPRC can now make a more informed decision on where and how Overseer should be used within the catchment.