Soil quality impacts of geothermal water irrigation on horticulture land in the Bay of Plenty region Bay of Plenty Regional Council

Environmental Publication 2025/07
Prepared by: Tanya O’Neill (Soil Synergy) and Reece Hill (Landsystems)

Report objectives 

• Conduct a desktop study to explore the potential impacts of mineral-rich geothermal water on soil 
  health, focusing on the effects of boron (B), sodium (Na), potassium (K), and chloride (Cl), with 
  secondary consideration of zinc (Zn) and arsenic (As).
• Investigate soil contaminant thresholds pertinent to the contaminants above and to common 
  horticultural practices in the Bay of Plenty where application of mineral rich TGS groundwater 
  occurs.
• Compile all available soil quality and trace element monitoring data collected by BOPRC from sites 
  irrigated with mineral-rich TGS groundwater.
• Prepare a report on the current state and trends of soil quality and trace element monitoring at 
  horticultural sites in the Bay of Plenty, irrigated with mineral-rich TGS groundwater.
• Provide a comprehensive assessment of the physical, chemical, and biological properties of soils 
  at horticultural sites irrigated with high-mineral TGS groundwater.
• Provide recommendations on soil quality and trace