Rotorua’s wastewater system was “unable to cope at several points” during last night’s heavy rain resulting in overflow into Lake Rotorua.
The city bore the brunt of Tuesday’s intense rainfall with authorities warning of fresh slips and potholes this morning.
“Due to the heavy rain and the very high water levels of the lakes and groundwater table, stormwater caused excessively high inflows to the Rotorua wastewater system which was unable to cope at several points last night,” Rotorua Lakes Council said in a statement today.
“Issues included wastewater overflowing into a stormwater drain leading to Sulphur Bay for several hours in the early evening and fully treated effluent overflowed from the holding ponds at the Rotorua WWTP [wastewater treatment plant] to the Puarenga Stream for a period in the late evening.”
“Council and its contractors worked throughout the night to minimise the impact of this and reported to BOPRC, mana whenua and other stakeholders about what was happening.”
Other network overflows occurred at Depot St, Lake Rd and Victoria St, and a wastewater pump station at Tikitere became blocked with rags, combined with high flows, caused an overflow to land.
The blockage has since been fixed.
Weather warnings were due to be lifted for the region early Wednesday but more rain was forecast for today.
Metservice duty meteorologist Mmaphapelo Makgabutlane said Rotorua had received 114mm of rain in 24 hours up to 6am today.
“In a typical May, Rotorua would get around 142mm,” Makgabutlane said.
Galatea recorded 92mm of rain in the same time period.
The heaviest rainfall in Rotorua occurred between 4pm and 5pm yesterday when 44mm fell in the one hour. The hour before that 20mm fell.
“Some places got a huge dumping of rain,” Makgabutlane said.
Metservice’s station at Tauranga Airport had measured about 71mm of rain while across the Coromandel 50mm to 60mm of rainfall was recorded with 78mm of rain recorded at Metservice’s Goldcross station.
Waka Kotahi NZ Transport Agency advises that due to high river levels, State Highway 2 Pekatahi Bridge has been closed.
“The river is approximately 600mm below the bridge deck.
“With more water collecting from the hills, the decision has been made to close the bridge for safety reasons until the water subsides.
“The detour for northbound traffic is through Tāneatua Rd, Arawa Rd, Hinemoa St and State Highway 30 towards Awakeri. Southbound traffic will use the same route, in reverse.”
Meanwhile, SH36, between Jackson and Central Rd is closed as was Hamurana Rd, between Mourea and Unsworth Rd, where crews were clearing large rocks and logs.
SH2 is closed at Maniatutu, between the Tauranga Eastern Link and Pikowai Beach, due to flooding at the Kaikokopu Stream Bridge. A short detour is in place via Paengaroa.
SH30 between Tiketere and Rotoma was affected by multiple slips with temporary traffic management in place.
Due to flooding at Kaikokopu Stream Bridge, SH2 is closed between Wilson Rd and Maniatutu Rd. A detour is in place.
Rotorua Lakes Council said crews were inspecting areas in Ngakuru, Rerewhakaaitu, Reporoa and around Spencer Rd this morning and contractors were repairing potholes in urban areas.
Bay of Plenty Civil Defence says new potholes are likely to have formed overnight after the wet weather and motorists should watch their speed.
It asked people to plan their journey and expect delays given the several road closures, including state highways.
It said the heavy rain warning had passed but people needed to be aware there could be surface flooding in areas, especially those low-lying.
Bay of Plenty Regional Council said all major rivers were expected to reach warning level one, with some also reaching warning level two. Landowners in affected areas were being notified to move stock from low-lying areas.
The regional council said many of the district’s streams had risen significantly as had the lakes, some by at least 100mm.
Bay of Plenty Regional Council duty flood manager Peter Blackwood said the Whakatāne River had passed the second warning level and was expected to peak this afternoon.
The river was spilling on to land, but still well within the stopbank area.
Several local roads were flooded in the area (Awahou Rd, Reid Rd, Taneatua Rd and Rewatu Rd) and they had been temporarily closed but full access would be available on Friday morning.
People were urged to keep an eye on the Whakatāne District Council’s Facebook page for updates.
The Kaituna River also reached its second warning level, peaking overnight, and both the Waioeka and Otara Rivers were now receding, Blackwood said.
“Significant stormwater flooding also occurred in Tauranga and through the Western Bay of Plenty and at its peak, Katikati Tauranga and the Rangitaiki catchment all experienced up to 50mm of rainfall in a one-hour period.”
“Our staff on the ground are busy fielding calls from landowners and manning flood pumps.”
He said while the weather system had passed, river and drainage water levels were still high and some may keep rising. Monitoring would continue.
He said several of Eastern Bay rivers reached the first warning level overnight on already very saturated land.
Matahina Dam continued to spill to lower levels in Lake Matahina and relieve pressure off the lower part of the Rangitāiki River.
There was a lot of rain in the upper catchment, he said, making the lake high which is why the controlled spilling continued.
While the heavy weather warning had lifted, there was more rain forecast for the next 24 hours and he said the regional council would continue to monitor the situation from its Flood Room.