31 May 2024

Media: Local Democracy Reporter

Topic: Rain event last week

Enquiry

*NOTE: enquiry was also sent to BOP Regional Council and BOP Civil Defence Group

I have some follow up questions I would like answered please. Also pasting the regional council's response to me below so both are together.

I think I am correct in that this event resulted in the second highest stream level on record (since '76) - the 2018 level was 50cm higher. I do not think should be overlooked. Given this, I think there is a significant level of public interest and I would appreciate direct responses to questions.

Following last night’s severe weather, and in anticipation of possible further impacts today, Bay of Plenty Regional Council’s Flood Team has been closely monitoring the situation across the region. This includes overnight monitoring of river levels, flows and rainfall via our Duty Flood Manager.

In response to the rapidly rising river levels in the Ngongotahā Stream this morning, the Flood Room was activated at 9.15am. This means the flood team is set up in our dedicated Flood Room and we have a flood monitoring team out in the field. It’s their job to be the eyes and ears on the ground, checking flood defences (such as such as stopbanks and floodwalls), monitoring river levels, flows and rainfall, and reporting back to the Flood Room.

Any information we gather from both on-the-ground and our Flood Room is then provided to other agencies, such as Emergency Management Bay of Plenty, and local authorities, such as Rotorua Lakes Council, in a timely manner to support their decision-making processes, including community evacuations.

Please note, the Ngongotahā Stream peaked at 5.39m at 10.35am and has been subsiding since.

Questions:

• Is any review or analysis to be undertaken following the weather event and what would this involve?
• How many complaints has either council received relating to the weather event? How many related to a lack of communication or warnings?
• If a duty flood manager closely monitors overnight, why was the flood room not set up until 9.15am? The stream started rapidly rising three hours before.
• When did the regional council first provide information to RLC that would allow for them to make an informed decision on whether there should be any evacs? What was it?
• "Today’s increased water levels in Ngongotahā was not sufficient to declare a state of emergency and we are unaware of any life-threatening situations."

I did not ask if a state of emergency should have been declared. At what level does the stream need to reach before any kind of warning or action is taken, and what is it? Any subsequent levels and corresponding actions/warnings? Are there any actions or warnings triggered by localised rainfall, and what are they?

• From 5am the council got calls of weather-related issues - couldn't this be called an indication that things were possibly more intense than first forecast?
• Regional council advised us that peak levels were reached at around 10:45am and rain forecast was subsiding. The catchment that incorporates Ngongotahā Stream appears to have had a lot more rain than the rest of the district. Self-evacuations in Western Road were encouraged as a precaution, given the known vulnerabilities of the Ngongotahā Stream, and this was communicated as soon as possible after the decision was made. As part of that communication others living near waterways were encouraged to remain alert and contact council for advice if they were considering self-evacuation.

How was this communicated?

It is well understood the catchment can receive far larger amounts of rain than others - as it did in 2018 - and as above there are known vulnerabilities at the stream. I believe the watch even noted localised torrential downpours possible.

The resident's concerns focused on how the situation was already happening hours before there was any comms, as well as the potential for things to have gotten a lot worse - hence his saying a timely response was critical. I have heard from others who were in the area advised to voluntarily self-evacuate who were never contacted, including in person.
With these things in mind, was the response to the event appropriate? Please explain.

• Referring to the unpredictability of weather and the need for people to be alert/prepared to act, "we think the community understands this".

Not everyone in the catchment would have lived there during the 2018 event, and may not know the risks. The stream started rapidly rising between 6am to 6.30am, a time many people would have been asleep. Why base your communication of a potential emergency on something you know can be unpredictable? Is this appropriate or does this need to change?

• Why was there no pre-emptive warning or alert?
• In May 2022 a storm brought the stream level to 4.22m. Rotorua Lakes Council staff visited properties in the Ngongotahā area to advise of a potential need to evacuate, which did not eventuate. This was 0.6m below the estimated spill level for streambank overflow at Western Rd and Brookdale Drive.

Last year it peaked at 5.07m during a January storm, resulting in minor stopbank overtopping that was able to be contained.

Has anything changed in regards to stopbanks since 2022 and what?

• Were there any breaches in this months event and where?
• How did the responses to potentially emergency situations change as a result of the 2018 flood?
• How effective were these on Tuesday?
• How effective were flood mitigation measures and how so?
• Flood mitigation works: Phase 1 is the high flow bypasses and may commence as early as December 2022. Phase 2 is the proposed stopbanks, floodway, and raising of Western Road, this Phase has more complex challenges in terms of land access and approvals and we are hoping work on this can commence in the 2023 earthworks season. This is from 2022 update - can I please be advised of any changes? Are these complete?
• I understand the review of the 2018 event was to gain an understanding of the flooding cause, and how similar flood impacts could be avoided in the future.

One section of the review recommended an emergency management plan was urgently developed, in conjunction with the community, that included clearly understood and communicated trigger levels for flood warnings and evacuations.

"With approximate rainfall based, triggers established, it will be possible to provide advanced warning, particularly of larger events where overflows at Brake Road and Brookdale Drive may occur. Rainfall forecasting information could also be used to allow initial alerts to be raised for the possibility of flooding.” “A flood alert and warning system will allow more time for evacuations to take place prior to flood waters arriving, especially on Western Road, Pioneer Road, Brookdale Drive and Oakland Place.”

Can I please be provided with this plan?

If there is one can I please be pointed to where it can be found?

• Why has there been no public update (seemingly) on the Ngongotahā Flood Review Project since February 2023?

Response

From Rotorua Lakes Council Group Manager Infrastructure and Environment Stavros Michael:

It’s standard practice after a partial or full activation of the Emergency Operations Centre to hold a de-brief to capture any learnings and opportunities for improvement. We’ll also debrief with other agencies involved.

We believe the response to the 21 May weather event was appropriate and proportionate to the situation, based on reports and information from staff, residents, police, FENZ, BOPRC, our contractors and weather agencies at the time. We acted as soon as we became aware of a potential emerging situation at Western Road.

There was no other situation we were made aware of that morning where lives were at risk and we received no reports of homes being flooded. Reports coming in were largely related to surface flooding, treefalls and slips which is usual during rain events. The first call received was at 5am about a treefall and further reports started coming in from 8am.

Police told us they received a call from a concerned Paradise Valley resident and visited the area but nobody they spoke to was in distress or danger.

We appreciate people get anxious and concerned in situations like this. People living near waterways are generally very aware of water levels and should be prepared to evacuate if the need arises. People should not wait for a notice to evacuate if they feel unsafe and can call Council to assist if needed or 111 if it’s an emergency.

Weather can always be, or become, worse than forecast, which is why we monitor what’s happening and based on information to hand, assess what, if any, action is required, including communications.

We will continue our efforts to educate the public and work with communities to ensure people are prepared and know what to do.

Re complaints: We got one, from a Paradise Valley Road resident. We’ve since spoken to him and believe we were able to allay his concerns.

Re people who said they weren’t visited: Our welfare team were sent to Western Road to make sure residents were aware of the situation and to encourage them to consider self-evacuating as a precaution. The team was stood down when the situation started to abate, before they were able to get to every property.

From BOP Regional Council:

*NOTE: BOPRC addressed questions related to its role/work

They clarified the following:

• Confirming the river level last week was the second highest stream level since 1976.
• The role and function of the Flood Room for context – below is a summary, but you can find full details on our website: Flood Room (boprc.govt.nz)
  The Flood Room is our dedicated ‘operations hub’, designed to support our flood team, so they can be effective and efficient when it comes to gathering and sending out timely information.
  During a flood, weather events or even periods of heavy rain, the Regional Council flood team supports a range of agencies (such as emergency services and local councils) with real-time environmental information (such as rainfall data and river levels) that can assist with their planning and response with local communities.

All answers [below] can be attributed to Engineering Manager and Flood Management Lead, Mark Townsend.

Is any review or analysis to be undertaken following the weather event and what would this involve?
Yes, Regional Council have already undertaken an event debrief, which included analysis of available data and communications. This will be followed up with a debrief with Emergency Management Bay of Plenty and Rotorua Lakes Council.

How many complaints has either council received relating to the weather event? How many related to a lack of communication or warnings?
No complaints have been received.

If a duty flood manager closely monitors overnight, why was the flood room not set up until 9.15am? The stream started rapidly rising three hours before.
We have a process that outlines when to activate. Activation is triggered by several factors, including forecast rainfall amounts and river and / or stream levels.
When activated, the response is for our team to set up in the Flood Room (a physical room inside our Whakatāne offices), where additional support can be provided to the Duty Flood Manager. At the same time, our rivers and drainage operations team are in the field checking infrastructure (i.e. floodgates, stopbanks etc).
The rainfall forecasts and recorded rainfall overnight (between Monday and Tuesday) did not trigger any thresholds in the process. The Ngongotahā Stream rises in response to rainfall on a regular basis, the amounts that were recorded prior to 8am were below the threshold (57mm was recorded at Relph Road over the five-hour period prior to 8am).
Between 8am and 9am, a rapidly moving downpour came through the area (37mm was recorded at Relph Road during this period). These are usually associated with thunderstorms and are very hard to predict.
This contributed to the stream levels rising rapidly and, therefore, we activated to provide support.

When did the regional council first provide information to RLC that would allow for them to make an informed decision on whether there should be any evacs? What was it?
The Duty Flood Manager provided an update to the Emergency Management Bay of Plenty Duty Manager (EMBOP) and the Group Manager at 9am. This information was acted on by EMBOP and Rotorua Lakes Council (RLC), and resulted in their decision to advise residents to self-evacuate.

In May 2022 a storm brought the stream level to 4.22m. Rotorua Lakes Council staff visited properties in the Ngongotahā area to advise of a potential need to evacuate, which did not eventuate. This was 0.6m below the estimated spill level for streambank overflow at Western Rd and Brookdale Drive.
Last year it peaked at 5.07m during a January storm, resulting in minor stopbank overtopping that was able to be contained. Has anything changed in regards to stopbanks since 2022 and what?
It’s important to note a distinction between stopbanks and stream banks:

• Stopbanks only exist on the Ngongotahā Stream, downstream of Ngongotahā Rd. Stopbanks are man-made structures, and are assets managed and maintained by Regional Council.
• Upstream of this area, there are stream banks only.

As such, all references in your question should be to stream bank overtopping (not stopbanks).

There was no stopbank overtopping and no physical works needed to be done because of the 2022 storm mentioned.

Were there any breaches in this month’s event and where?

There were no breaches (this is when a stopbank fails), or any overtopping of the stopbanks. However, the stream banks were over topped on Western Rd.

As previously mentioned, stream banks are not a flood protection asset of Regional Council.

Flood mitigation works: Phase 1 is the high flow bypasses and may commence as early as December 2022. Phase 2 is the proposed stopbanks, floodway, and raising of Western Road, this Phase has more complex challenges in terms of land access and approvals and we are hoping work on this can commence in the 2023 earthworks season. This is from 2022 update - can I please be advised of any changes? Are these complete?

For context, and as you may be aware, the Ngongotahā Flood Mitigation Project is one of six workstreams outlined as part of the 2018 Ngongotahā Flood Review.

The direction to Regional Council was to consider additional flood protection works, which could include the construction of new flood protection, the impact of new assets or maintenance on existing flood protection structures (stopbanks), and the possibility of needing to upgrade those exiting structures.

Since then, we have undertaken a large programme of work, which includes hydrological modelling, data analysis, optioneering and feasibility around what structural works could look like. This was done in consultation with a Community Reference Group, which was established following the 2018 review and recommendations.

As with any project of this size and scale, balancing the needs of the various communities and landowners in this area is paramount. This also includes balancing the risk with affordability to targeted ratepayers in the Kaituna Catchment Control Scheme.

As such, the time to develop a solution that meets the needs of all parties has taken longer than anticipated, and so construction did not begin as planned in 2023/ 2024.

Currently, designs for potential flood protection in the area are nearing completion. Once these designs are ready, we will be able to provide a more accurate cost estimate, and be in a position to have a conversation about the proposed works with the community.