Tuesday, 26 May 2020

WHITIANGA WEATHER

What’s the story with our water restrictions?

According the latest NIWA “Hotspot Watch,” most of the Waikato (including the top half of the Coromandel Peninsula), Auckland and Northland are experiencing drought conditions, with “severe drought” in pockets of the Far North and Great Barrier Island.

Why is it then that most of the drought-stricken areas are subject to lesser water restrictions than the top half of the Coromandel?

Whitianga, Hahei and Coromandel Town remain on a total watering ban, which is similar to the Level 4 water restrictions in place in Dargaville and Baylys Beach in Northland. Lower water restriction levels are in place in all other towns and cities in Northland - Level 3 restrictions (no hoses or sprinklers) in Kaitaia, Level 2 restrictions (no sprinklers) in Kerikeri, and residents and visitors to Whangarei are asked to use water sensibly.

No water restrictions are in place in Auckland. In the Waikato, Hamilton and areas on the outskirts of the city are subject to Level 2 water restrictions (sprinklers to be used on alternate days, but hand-held hoses can be used at any time), and Level 3 restrictions (no sprinklers, but hand-held hoses can be used at any time) are in force in Te Awamutu and surrounding areas. The rest of the Waikato isn’t subject to any water restrictions.

A total watering ban came into force in Whitianga, Tairua and Hahei on 30 December last year and in Matarangi on 1 January. Water restrictions eased slightly in Whitianga, Tairua and Matarangi on 6 January, but a total watering ban was reinstated in Whitianga on 10 January. On 14 January, a total watering ban came into force in Coromandel Town as well.

At the moment, Whitianga, Coromandel Town and Hahei remain subject to a total watering ban, while hoses, sprinklers and garden irrigation systems can only be used in Matarangi on alternate days, and Tairua residents and visitors are asked to conserve water.

Because of the lack of rain, the owners of most properties in Mercury Bay not forming part of one of Thames-Coromandel District Council’s water supply schemes (eg properties in Cooks Beach and Opito Bay) have no choice other than to purchase water to fill the tanks on their properties from bulk water supplier, Whitianga Water Cartage (WWC). The total watering ban in Whitianga and Coromandel Town is forcing WWC to fill their tankers in Thames, the only town on the Coromandel not currently subject to any water restrictions. The extra distance WCC has to cover to obtain water comes at a significant extra cost, which they have to pass on to their customers.

Most of the TCDC water schemes in the wider Mercury Bay area get their water from local rivers and streams - Whitianga from the Whangamaroro River, Matarangi from the Opitonui River, Coromandel Town from the Karaka Stream and Waiau Stream, and Tairua from the Pepe Stream and tributary. Hahei get their water from a groundwater bore.

According to Bruce Hinson, TCDC’s Operations Group Manager, water restrictions on the Peninsula are determined by supply and demand, and are not just a response to high numbers of visitors to the Coromandel. “Restrictions are also about meeting the specific requirements of [our] resource consents from Waikato Regional Council [under which] we draw water from,” he says.

“On the supply side, we are limited by [our] resource consent conditions as to the amount of water we can take, while protecting the health of the water source.

“With any water resource consent, we can’t apply for a variation to increase the take. We would need to apply for a new resource consent, with this process potentially taking considerable time and money. [With regard to Whitianga, our] current consent for the Whitianga [water] supply is sufficient to meet demand, with the consent valid until 2025. As part of the activity management planning council undertakes every three years, the supply and demand for each township is assessed and if future demand exceeds supply prior to a resource consent expiring, council will commence an application for a new consent prior to the expiry date.

“There is also no issue with the Whitianga water treatment plant’s capacity to process drinking water. The plant is new and can treat water to a high standard. It also has a modular design which means treatment capacity can be increased in the future.

“The issue we are currently experiencing with water restrictions is an increase in demand for water due to our peak visitor population, exacerbated by the hot, dry weather, which has seen our river and stream levels decrease. This in turn means the water volumes we can take from some sources is less, so we don’t breach our resource consent conditions, which often have a condition that limits the volume allowed to be taken during times of low stream flow. As the dry weather continues and large numbers of people remained on the Coromandel over Anniversary Weekend and [is expected for] the upcoming Waitangi Weekend, the need for water restrictions continues.

“Water restrictions are based on assessments of the current levels of the water sources, the level of demand along with the short-term and long-term weather forecasts and projected numbers of visitors coming to the Peninsula. For example, the weekend before last we had approximately 17,000 people in Whitianga for the [Whitianga Summer Concert]. This week, we anticipate a large number of visitors for the Leadfoot Festival, Waitangi Day falls on Thursday and it’s anticipated many people will take Friday off for a long weekend on the Coromandel. The short and long-term weather forecasts are predicting very little rain.”

Longer term demand for water due to population growth is continually being assessed through TCDC’s asset management plans and Water Demand Strategy. “From these… pieces of work any proposal for a new a water reservoir would then be formulated,” says Mr Hinson. “A dam would be highly unlikely as these are extremely hard to get consent for.”

According to Lewis Farris, a Metservice Communications Meteorologist, the current dry conditions on the Peninsula is caused by persistent high-pressure systems favouring Northland and extending a ridge over the upper North Island. “We have seen this before during the summer period,” he says.

“Looking ahead… there are signs that we should start to see some low pressure [systems] developing over the Tasman Sea as February wears on, replacing the high pressure that has been a strong feature of the last two months. This is the first hint that we should see a better chance of decent showers, or some rain at times, into the Coromandel for the middle and latter parts of February.”

Total rainfall of 5.8mm was recorded in Whitianga during last month, making it the third driest January in town on record. The driest January was in 1950, when 2.6mm of rain was recorded. In December last year, 53.2mm of rain was recorded. In December 1949, just before the driest January to date, 77.2mm of rain was recorded.

Total rainfall in Whitianga during 2019 was 1,327.4mm, just over half of the town’s normal annual rainfall.

If we understand Mr Hinson correctly, although not the only reason, the influx of visitors to the Coromandel over summer seems to be the main reason why the top half of the Peninsula is subject to more severe water restrictions than the other drought-stricken areas of New Zealand. Will we see the restrictions ease after Waitangi Weekend? Only time will tell.

Pictured: A stretch of the Whangamaroro River last Sunday afternoon.A stretch of the Whangamaroro River last Sunday afternoon.Thames-Coromandel District Council is taking water for their Whitianga Water Scheme not far from the spot where this photo was taken

 

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