Waikato Regional Council is warning that chemicals on board a truck that crashed on the Kaimai Ranges this morning might have entered a nearby stream.
It's understood the truck rolled on State Highway 29, between Rapurapu Kauri Track and Kaimai Mamaku Lookout, shortly after 6am today.
The truck was carrying large containers filled with sodium hydroxide, with approximately 3000 litres spilling from the truck, resulting in the closure of the Kaimai Ranges.
Emergency services are in attendance and a detour is in place.
The council's incident response team is attending the scene to assess the environmental impact of the incident.
In the meantime, staff have contacted the nearest five water take consent holders on the expected path of this spill to advise them. However, there may be others taking water on the Mahina-A-Rangi Stream down to the Waiomou Stream.
Until more is known about the extent of the spill, water users are urged to exercise caution.
Waka Kotahi NZ Transport Agency advises State Highway 29 is closed in both directions after the containers fell from a truck about 500m south of the summit.
The road is expected to remain closed for much of the day to enable clean-up.
Motorists are encouraged to delay their travel where possible. Detours are State Highway 36 and State Highway 5 via Rotorua or State Highway 27, State Highway 26 and State Highway 2 through the Karangahake Gorge and on to Tauranga. These detours will add considerable time to journeys and are not suitable for High Productivity Motor Vehicles (HPMV).
Visit the interactive Journey Planner website (journeys.govt.nz) for up-to-date information on the road closures, detour routes and traffic in the area.