The Flood of All Floods

Ohinemuri Regional History Journal 50, September 2006

(By Graham Watton)

THE OHINEMURI district has been plagued by floods for hundred if not thousands of years since the Ohinemuri River flowed down its present course. There were no stopbanks in those early days, the Ohinemuri River overflowed its channel at the end of the hospital high ground and flowed northwards down through the low lying area until the floodwaters reached the Waihou River from the Puke to the Komata Stream.

I found a report in the Ohinemuri Gazette of June 22, 1898, of a flood which sent water two feet deep (60cm) down Belmont Road and inundated all the low-lying areas of Paeroa including the area west of the railway line known then as the Ohinemuri township. At that time this was the largest flood in living memory, bearing in mind the Thorp family had been residents since 1842.

The Ohinemuri River has as its catchment area the Waihi Basin, the Waitawheta and Waitekauri Rivers Valleys. All three catchments have twice or three times, even more, rainfall than Paeroa during these periodic intense rain storms. All this water spills out of the Karangahake Gorge on to the flat land before it reaches the Waihou River.

Paeroa was born in the 1840 with the arrival of the Thorp family and by 1870s the township was being developed. During the late 1890s and the first decade or so the 1900s floods continued to be a regular occurrence, three and four times a year, causing damage to property and land. The floods got bigger and bigger even though on each occasion the rainfall stayed about the same.

The Government of the day was held responsible for the increased devastation. The politicians in 1895 had bowed to the pressure of the rich mining industry and passed an Act of Parliament creating the Ohinemuri River a sludge channel.

Paeroa with Opatito Road in the foreground across to Taylor’s Avenue.

This Act gave several mining companies at Karangahake, Waitekauri and Waihi an undisputed licence to dump an estimated 100 tons per day of mining tailings—the talcum-like residue after the bullion had been extracted--into the Ohinemuri River and its tributaries.

While these deposits "killed" the fish and plant life in the river when the tailings reach the slow moving waters of the river in the flat areas around Paeroa, sediment fell to the bottom and built up the river beds, making the river channel shallower by the year.

Following major floods in 1904 and 1907 and smaller ones in between the local residents called for an investigation into the causes. A Royal Commission of Inquiry was established to investigate the flooding and to make recommendations on remedies to overcome these disastrous events.

The Commission sat in 1910 and while finding fault with the 1895 Act of Parliament, it did not recommend its repeal. Instead The Commission proposed a flood control scheme for the district to be known as the Waihou and Ohinemuri Rivers Improvement Scheme. The scheme was considered too costly for local land owners to meet and it was reduced in size.

Finally agreement had been reached and stopbank construction started in 1912 and continued until around 1924. The scheme saw stopbanks on both sides of the Ohinemuri through Paeroa to its confluence with Waihou River. The Waihou River was also stopbanked for some distance above and below Paeroa.

But Ohinemuri River continued to silting-up and there major floods in 1917, 1924, 1936, 1954, 1960, 1964 and again in 1976. There were other minor floods annually. The sludge channel Act was repealed in 1955 after the Waihi Gold Mining Company's Victoria battery at Waikino ceased operations in 1953.

Waikino from the air after the Ohinemuri River swept through

The stopbank system just held the rivers, but after the Komata River stopbanks were breached in 1960 and again in 1964, the Hauraki Catchment Board proposed a new scheme, the Waihou Valley Flood Protection and Erosion Control Scheme for the total Waihou River catchment, from its mouth at Thames to the headwaters, in the Mamuku Range overlooking Rotorua.

When first design was adopted by the Board in 1965 the scheme was estimated to cost 6 million pounds ($12 million). For the next decade there was a considerable war of words between the land-owners, the Catchment Board and the Government over the design and the cost--shades of 1910.

Finally in 1971 the first sod of the now $14 million scheme, was turned at Netherton and stopbanking the Waihou River commenced. This was the largest and most complexed flood control scheme ever attempted in New Zealand.

An acceptable funding formula between the land-owners and the Government took another decade to settle, and included bitter debates, threats of legal action and a hotly contested classification scheme which was the base for rates to be levied.

The Catchment Board was the "ham in the sandwich" as it were. By now the cost of the scheme had escalated to around $80 million dollars.

Finally the impasse was broken by Prime Minister Rob Muldoon when he visited Paeroa to open the new Paeroa Racing Club stand, in November, 1981. In a special interview in the corner of the new stand he set the subsidy formula. There were no representatives of the Catchment Board or the Government departments present, the Prime Minister's decision took all by surprise and it was in line with what the Catchment Board had been seeking for several years.

There is no doubt that this decision was forced upon the Government following the disastrous flood of the Thames Valley on April 12 and 13, 1981, when an estimated $12 million worth of destruction was created in an area only about a quarter of the total catchment of the scheme.

This was a 100-year flood in the Ohinemuri River and had its beginning on Saturday, April 11, 1981, when rain started over the Coromandel Range between Tapu and the Waitawheta Valley. The downpour got heavier by the hour throughout the night and continued on Sunday.

The Ohinemuri River by Sunday afternoon was running at a 5-year flood level and the Catchment Board staff were checking stopbanks and rising river levels. Warnings had gone out to farmers to move stock from the lower levels.

Household effects in Menzies Place

Paeroa's low-lying areas were beginning to pond with the runoff from the hills surrounding the town and from surface water. The rising river had closed the floodgates on the Main Drain, Opukeko and Stocks (near the maritime park) drains. Therefore there was no internal drainage apart from that given by three small diesel-engined operated flood pumps, which had no way of coping with the huge run-off.

Milkman Brian Dunham went to pick up his supplies from his chiller in Francis Street at about 5 p.m. He found water running down Francis Street about 300mm deep. On checking where this flow was coming from he discovered the partly completed 1500mm flood gate culvert under a new stopbank at the end of Wharf Street had ruptured under pressure from the rising river, which was by now nearing the 8m mark at the Criterion Bridge.

Catchment Board, Paeroa Borough, Ohinemuri County and Hauraki Plains County staff and a team of volunteers were quickly assembled in Wharf Street. Sand was brought in by the truck loads, work commenced on filling sandbags and building a coffer dam around the troubled pipe to stem the flow of water.

The Paeroa Volunteer Fire Brigade was out helping residents, while the ambulance service was on standby.

The 50 to 60 men laboured in atrocious conditions, gale-force driving rain, mud and darkness.

A state of civil emergency was declared at 6 p.m. and this organisation was quick to establish a welfare section in the Open Brethren Church in Wharf Street to provide hot drinks and food for the volunteers.

The area of Paeroa west of the old railway line embankment was filling fast as the floodwaters swept along Francis Street and Marshall Street and through the William Street subway. Water was also finding its way down to the lower end of the town.

Three families were evacuated from the area west of the railway line while several others left their homes to stay overnight with relatives and friends on higher ground.

By about 8 p.m. the Ohinemuri River peaked at 8.4 metres at the Criterion Bridge, where a close watch was being kept with sand bags at the ready to stop the water running through the bridge approach.

The water level started to recede and by 11 p.m. the work force was stood down for the night—the danger had passed. Some volunteers stayed on overnight improving the coffer dam as the weather forecast was far from good.

The rain had eased a little in the Waihi catchment, but by Monday morning it had intensified. Torrential rain fell all Monday, causing additional concerns at Wharf Street. From late Saturday to late Monday more than 550mm fell in the Waihi area.

The Ohinemuri River was on the way up again. When the 6m mark was passed at Karangahake, at about 2 p.m. the Paeroa Civil Defence was again in high alert and its various sections swung into action.

The Paeroa Civil Defence braced itself for a massive flood.

Farmland from Paeroa to Kopu was inundated with flood water.

Main street shopkeepers were warned to sandbag their premises and evacuate. All residents in the mid to low-lying areas of the town were placed on notice that they could be evacuated, and this operation started in the area west of the railway embankment by 4 p.m.

The Ohinemuri River continued to rise at an alarming rate. News came through at 5 p.m. that Waikino had been washed away by a surge of water a metre high. This was now sweeping down the gorge. It flowed 60cm deep through the rail tunnel.

By 5 p.m. the river had reach the previous night's level and was still rising at the Criterion Bridge. Both ends of the bridge were sandbagged to stop water spilling out through these gaps. Floodwaters started to trickle over State Highway 2 by the Dell, next to the hospital hill.

Emergency services and civil defence rescue units worked in failing light to ensure that all residents were moved to higher ground, the Miller Avenue and Central Schools were the main evacuation centres. Many went to relatives and friends, but all had to be accounted for by the Civil Defence.

On the other side of the river Rotokohu to Tirohia was one huge lake. Residents in the area were evacuated to the Tirohia School.

The Civil Defence Organisation, through dedicated teams of volunteers working for 24 hours on end keeping trace of some 500-600 people evacuated in Paeroa and another 200 between the Rotokohu-Tirohia area.

By 6 p.m. the river reach 9.5 metre a record of any flood, a metre above the huge flood of 1936, which had been considered the flood of all floods.

The water was some 300mm up the steel girders of the Criterion Bridge. Huge logs swept along by the raging torrent slammed in the bridge, with a resounding clang, to disappear under the bridge and surface 200 metres down stream.

The river level steadied for 30 minutes and there were huge sighs of relief by everyone involved—the river had peaked. The Civil Defence now turned its attention to the welfare of the evacuees.

But worst was to come.

Reports came through 6.30 p.m. that flood water was running across the railway line at the end of Flora Street, into the Taylor's Avenue area, spreading north and south and levels were rapidly rising.

There was only one reason for this: There had been a stopbank failure.

A small team of Catchment Board staff lead by Board Engineer Kevin Simson, went on a hazardous stopbank patrol, in driving rain and darkness, from the railway bridge down stream.

On reaching Maori Road they came across a 50-metre gap in the stopbank with flood water pouring through the gap into the Junction Road area. The gap was being enlarged by the second to finally become almost 100 metres wide. There was no way to stem the flow.

Later it was found that an oak tree growing in the toe of the stopbank had been blown over, taking a large area of sodden ground and stopbank with it. This considerably weakened the stopbank already under threat of being topped.

Paeroa Civil Defence stepped up its evacuation procedures, emergency services and rescue teams toiled at fever-pitch pace in darkness and fortunately easing rain, to get all the residents in the mid to low lying areas to safety.

The floodwater flowed through the breach until around 2 a.m. on Tuesday morning at which time the river had fallen sufficiently for the water to flow back again, in other words the tide had turned.

When dawn broke on Tuesday, the sun shone from a clear sky down on a Paeroa more than half under water, from a few millimetres to 2 metres deep. To make matters worse the floodwaters had infiltrated the town's sewage system and became highly contaminated.

Some 1000 residents had been evacuated from 270 houses. Numerous houses, properties and businesses were inundated by the contaminated flood water.

It was a scene of total disaster. Fortunately there was no current of water to cause devastation to property. The only flat area of Paeroa above a huge lake of brown murky water was the central business area, from Hall Street to midway along Normanby Road from the post office. Boats provided the only access around most of the town.

It took a day before the water drained from the main street area, and another three to four days from the majority of residential sections but up to two weeks from the lower areas, like Menzies Place, and Shoalhaven Crescent.

Then came the massive clean-up. From Tuesday morning the Civil Defence, along with New Zealand Fire Service, the Ministry of Works, the New Zealand Army and Air Force, the Social Welfare Department were around the CD headquarters table preparing recovery plans.

Those residents whose properties were not entered by the floodwater were allowed back to their homes as the water drained from their sections. The residents whose homes were invaded by the contaminated floodwater were not allowed home and the delays were from one week up to six months for a couple of families.

The Army came in with two field kitchens to provide meals at the Army Drill Hall and the Tirohia School (for about 24 hours), while the Air Force provided an Iroquois helicopter and crew for almost a week to fly rescue missions in to the hill country where roads were almost non-existent in some valleys.

The Paeroa water supply was smashed at Karangahake. One New Zealand Fire Service appliance pumped water from the Ohinemuri River at the Dell to the town's treatment plant continuously for 100 hours from Tuesday morning to late Thursday to keep Paeroa supplied with treated water until large portable pumps were brought in from around the North Island.

Volunteers by the hundreds came to Paeroa to help home-owners to clean out their homes. On Good Friday and Easter Saturday it was estimated that 500 to 600 volunteers from as far afield as Hamilton and Auckland were helping to hose out homes and buildings.

The Army kept their field kitchen going in the Drill Hall, now the Baptist Church, for over a week to provide meals first for the evacuees and then volunteer workers.

The Paeroa Fire Brigade along with the New Zealand Fire Service crews from Auckland and Hamilton deserve the highest of the praise for their efforts. The Paeroa firemen were on the scene from the first alarm on Sunday spear-heading the evacuation and remained on duty until after Easter playing a prominent roll in the clean up.

There is one band of volunteers who deserve the highest of praise. They are the Paeroa firemen's wives and partners who manned the fire station for a week providing all meals and the needs for the 70 firemen on duty during the crisis.

Whole household lots of furniture, clothing, personal and even the most precious heirlooms saturated by the contaminated floods waters were consigned to the rubbish dump. More rubbish went into the dump in one week than would normally do so in a year. Anything contaminated with the floodwater was sent to the dump by the health inspectors and the insurance assessors. As each truck load was dumped it was covered with soil by one of two bulldozers. Security was tight to prevent looters.

Houses had their wall linings stripped to about 600mm above the water level. Then, with the use of high pressure fire hoses, the framing and floors were washed down, swept out and left to dry before being repaired.

Business people also received the same treatment, even steel tools were dumped. The entire Ministry of Works garage in Grey Street had to dump all its tools and parts—the workshop had almost 2 metres of water through it.

Fortunately the weather remained fine for the week to ten days after the flood. This help enormously to restore moral and confidence in the community, a community which had pulled together as never before to form one solid entity.

The farm land and communities of Komata, Hikutaia, Puriri, Matatoki, Kirikiri and Totara, between the Waihou River and the Coromandel Range, had already be devastated by flash flooding during the rain storm, and then were submerged by waters from the swollen Waihou River.

Thames suffered serious damage from water and silt swept down by its internal streams. Fortunately the Kauaeranga River did not top its stopbanks, it came within 150mm of doing so. Tararu, Te Puru and Tapu were also hard hit as their streams turned into raging torrents causing widespread flooding and erosion.

Immediately the extent of damage was known, by midday on Tuesday, a Thames Valley Flood Relief Appeal was launched. Donations of clothing, furniture, household items poured into the various depots established by the Civil Defence welfare section.

A special committee was established to look after the increasing amount of money being donated by a generous New Zealand public. The Government gave $20,000 to start the fund and then a $1 for $1 subsidy up to $250,000 of the money donated.

The fund quickly swelled, local banks launched their own appeals through their national offices, two Hamilton Radio stations, one headed by the Mayor of Hamilton, with a nation-wide listening audience collected $23,000; Lions and Rotary Clubs provided $80,000 between them, many firms made good-sized donations. When the fund was finally closed a total of $535,000 had been received. There was $285,000 from public contributions and $250,000 from Government.

This does not included the many truck loads of household contents, clothing and hay received and distributed.

The committee established its criteria for dealing with the claims, some were met immediately others took a little longer as insurance assessors worked their way through well over 1000 claims.

There were 310 applications to the appeal fund from the flood strickened area, which stretched from Paeroa to Tapu. Of this number 299 applications were approved and they received in the main from $100 to $3000 each. Twenty-six per cent of the applicants did not have any insurance and of those remaining many were well under insured.

Eighty of the claimants came from the Thames-Coromandel District Council, 15 from the Ohinemuri County Council and the remaining 204 from the Paeroa Borough.

It was estimated that the cost of the damage in Paeroa alone was in excess of $2 million. On top of this emergency repairs carried by the Hauraki Catchment Board to stopbanks and riverbank erosion was $450,000.

The farming community losses were estimated at $530,000 to cover the loss of machinery and equipment, stock ($100,000), hay (45,000 bales), many kilometres of fences, hectares pasture damage and hill erosion.

Highways and county roads took a real battering. For instance SH2 through the Karangahake Gorge was closed for a week, including Easter. SH25A, (Kopu-Hikuai) was also closed for a similar period.

And the most important feature of this whole calamity there was not a human life was lost. This is one of the two to standout features of an event which still lingers clear in the memories of those who were there. The other feature was the generosity of the nation. I believe it was one of the most supported disaster appeals ever launched in this country and the record is still with us.

But we do not wish this record to ever be broken, either here or elsewhere in this country.

By the late-1980s the Ohinemuri River stopbanks around Paeroa were completed as to were those on the Waihou River both above and below the confluence.

These stopbanks are designed to meet the demands of a 100-year flood and there is still a metre of freeboard to contain a 150-year-old flood.

Strangely enough the present flood control scheme is constructed to almost the same design measurements in stopbank height and width between banks as the scheme recommended by the Royal Commission in 1910.

Will we get a 150-year flood? The way the global weather pattern is at present any thing is possible.