A slip has taken out a chunk of Tai Rāwhiti's State Highway 35 north of Tolaga Bay, exposing underground wiring.
Heavy rain has hammered the region this week, with officials placing a state of emergency until Sunday.
Tai Rāwhiti Civil Defence said more than 40 roads were closed, and 35 families were sheltering in evacuation centres as of Friday night.
More than 150 people had evacuated their homes, and about 14 families were cut off by floodwaters in the Tolaga Bay region.
Gisborne residents are being asked not to flush toilets or do washing, as the city's wastewater system reaches capacity.
Tai Rāwhiti Civil Defence controller David Wilson said the pipes were overwhelmed by heavy rain coinciding with high tide.
MetService had forecast some easing in heavy rain sweeping Tai Rāwhiti, but a red rain warning was still in place.
Contractors are at work on the SH35 slip, caused by heavy rain overnight, about 1km past the Waiau Road turn-off.
The highway remains closed between Tolaga Bay and Tokomaru Bay.
Earlier, Civil Defence spokesperson Greg Shelton said roading crews were heading to the area to investigate reports the road had been affected by floods.
"North of Tologa Bay at the moment there is surface flooding and although it might not have been officially closed, I have heard back from contractors that today we have got issues," he said.
State Highway 2 north of Gisborne remained closed with Waka Kotahi reporting convoys would operate on Saturday afternoon along the route.
State Highway 50 between Ongaonga and Tikokino in Central Hawke's Bay was also closed due to flooding.
Orange heavy rain warnings were also in place for Hawke's Bay, Taihape and Manawatū, as well as in the Nelson and Marlborough regions.
MetService predicted a drop in rainfall, and intensity in Tai Rāwhiti - but Civil Defence said these remained significant amounts, and people should not become complacent.
Seventy to 100mm was expected to fall south of Tolaga Bay, and 150mm to 200mm north of Tolaga Bay.
Coastal and low lying areas could now expect 40mm to 80mm.
Peak rain intensities had also dropped to 15mm to 20mm per hour, down from 20-25mm.
Emergency management was keeping a close watch on the region's Hikuwai River.
Shelton said he was comfortable with the 9.1m height level recorded at the river monitoring station at Willowflat on Saturday morning.
"With more rain that could get up to 10, that's still within our comfort zone, Gabrielle was 14.6, around about 10-and-a-half we're getting concerned, so we've got a bit of leeway there yet," he said.
Civil Defence said rain was falling steadily in and around Tolaga Bay with some flooding.
Tai Rāwhiti Civil Defence said 11 evacuation centres were open, while another five were on standby.
Gisborne Mayor Rehette Stoltz urged residents to get in contact if they needed help.
"Our region is already so saturated, so we are expecting more landslides, we have a lot of surface flooding already on our roading network," she said.
"We are asking our community to be our ears and eyes on the ground to let us know if there is any place that they need assistance and we will come and help them."
She said the area was prepared to weather the storm and some communities had pre-emptively evacuated ahead of this weekend.
Fire and Emergency crews head to Tai Rāwhiti
Fire and Emergency sent two crews in late on Friday to help with flooding in Tai Rāwhiti.
It said one crew left from Hawke's Bay at 5pm and another landed from Auckland at Gisborne at 8.30pm.
They could help in multiple ways, Assistant National Commander Steve Turek said in a statement last night.
A separate flood rescue crew in Auckland had not been sent.
Any water rescue, if required, was being carried out by Surf Life Saving crews, Turek said.
This was standard practice in Tai Rāwhiti and FENZ had "the utmost confidence in the arrangement" to meet local needs.
"We are working within a declared state of emergency and therefore under the control of Tai Rāwhiti Civil Defence," he said.
"The flooding currently being experienced, while significant, is not beyond the capability of local multi-agency resources."
FENZ began training six flood rescue teams after Cyclone Gabrielle but most of them were not fully equipped yet or operational until mid-July.
However, the Auckland team has been stood up for longer, since shortly after the January Auckland Anniversary Day floods.
Mood gloomy in rural community as cyclone clean-up already delayed
A Tai Rāwhiti farmer said the mood was gloomy in the rural community.
Federated Farmers meat and wool chair Toby Williams said farms were already fragile so any rain would have a big impact.
He said many farmers gave up on cyclone clean-up work a few weeks ago because it was too wet and dangerous.
"Things aren't great if we're honest, it's very wet," he said.
Williams said weather events this year and over the last two years had taken a toll on farmers and others in rural communities.
"Morale started to really wane in farmers and with our rural residents and town residents, it's just really tough to be constantly dealing with weather warnings," he said.
Williams said with another week of wet weather ahead, people should get off the farm for a break if they could, and talk to someone if they were feeling anxious about the weather.