Clarence Valley State of Play: as the first day of Summer draws closer memories of past summers surface

 

Right now the Clarence River flow at Newbold Crossing is registering in the >80% stream flow percentile, the Shannon Creek side dam is at 99% capacity and soil moisture is for the most part within acceptable limits across the Clarence Valley which is classified 100% non-drought.

However, the Australian Summer officially begins on 1 December 2024 and air temperatures and water evaporation rates are bound to rise.

So how is the New South Wales Combined Drought Indicator (CDI) Map likely to look come December?

Where we are going?

NSW Dept. of Primary Industries and Regional Development, Climate Branch, Drought Forecasting, 17 November 2022:

NOTE: The DPIRD drought forecast for NSW presents the ‘Most Likely’ Combined Drought Indicator (CDI) category for the forecast period. The Most Likely CDI category is determined by identifying the 'mode' of the CDI. The mode is the category that appears most frequently across all possible forecast outcomes in the ensemble run. It is the most common prediction for drought conditions in the forecast period based on the model's simulations.

Where have we been along the Clarence Valley drought history continuum, 20 November 2019 to 9 October 2024?

Click on graphs to enlarge

Fine Flower & environs

Heifer Station & environs

Grafton & environs

Maclean & environs

Yamba

*All maps & graphs were created on 17.11.24 using interactive tools created by NSW Dept. of Primary Industries and Regional Development, Climate Branch

Combined Drought Indicators

The NSW Combined Drought Indicator (CDI) includes four indicators for rainfall, soil moisture, plant growth and drought direction which, used together, can indicate the five phases of drought.

Rainfall Index (RI)

The RI is the percentile rank of rainfall aggregated over 12 months. The ranking is made using a 30 year (1980-2010) baseline which captures recent big shifts in climate variability, and factors in climate change. This provides an index between 0 and 100 where values approaching 0 are close to driest, and those approaching 100 close to the wettest, for any given region. Percentile-based indices like the RI have a uniform distribution regardless of their climatic setting, which is an attractive feature in NSW given the presence of rangeland, temperate and sub-tropical climates which have skewed, normal and log-normal rainfall distributions.

Soil Water Index (SWI)

The SI is calculated using the same procedure as the RI, but uses a soil moisture field derived from the DPI AgriModTM soil water balance. Plant available soil water from layer one (0-10cm) and layer two (11-45 cm), the assumed maximum rooting zone, are aggregated and used to calculate the SWI. Similar to the RI, the SWI is an index between 0 and 100. In most districts of NSW a value of 0 means there is no plant available water held in the profile. The SWI is a hydrological index, but its configuration means that it is more useful as an indicator of conditions for dryland than irrigated agriculture.

Plant Growth Index (PGI)

The PGI is calculated using the same general procedure as the RI, using the output from DPI’s crop and pasture models. Crop stress and pasture growth data are taken from DPI AgriModTM, and the percentile rank calculated for each day. If the predominant land use in a given area is cropping, the PGI uses the crop-derived data, otherwise it uses the pasture growth indicator. The PGI is an agronomic drought index which is not only sensitive to moisture but also temperature variation and seasonal events such as frost. It is important to note that the PGI tracks the influence of climate on production potential across broad areas only. This provides a regional indicator of conditions. In the paddock, management decisions like fertiliser application and timing, sowing times and stocking rates drive outcomes on the ground, and in-field conditions can be above or below the regional indicator reported by EDIS.

BACKGROUND

The main water supply (other than the village systems of Wooli and Minnie Water) in the Clarence Valley is sourced from the Nymboida River, flowing through a section of the wider Clarence River catchment area.

At this time of year the Clarence Valley urban water supply is drawing around 14.26ML/per day from the river weir.

The Nymboida River also gravity feeds water to Shannon Creek Dam when required and, if the Nymboida river flow is too low (less than 225 Megalitres a day) or turbid post-flood, the Clarence Valley's principal urban areas receive water sourced from the off-stream storage at Shannon Creek.

Overall, Shannon Creek Dam is used to supply the Clarence Valley’s water about 5% of the time. Right now this dam is at 99% capacity.

This scenario is complicated by the fact that historically the Clarence Valley also supplies water out of the catchment to Coffs Harbour City local government area and this draw on catchment water is constant and always exceeding an optimal sustainability level for average daily drawn down.

Byron Shire Council being less than transparent over a proposal to cut more than 30 shire residents off from a reliable town water supply as a cost cutting measure

 

Echo, 10 July 2024, Residents face being cut from Mullum’s water, excerpt:

More than 30 affected residents say their properties are at the bottom of Wilsons Creek and some areas of Mullumbimby Creek, and they were only told they will likely be cut off from town water after questioning Council staff about the Mullumbimby Water Supply Strategy.

Spokesperson for the Wilsons Water Rights Action Group (WWR) Mel Macpherson said she was shocked to find out from a neighbour about Council’s plans to remove their connection to town water without any direct written or verbal communication.

‘One would think the appropriate action for Byron Shire Council would be to talk to us individually, and let us know that their preferred water strategy means cutting us off – for the 30 residents this has drastic ramifications, we have a right to know.

‘I honestly feel the communication from Byron Council has not been acceptable at all. This decision directly affects our health, businesses, infrastructure and property values. Relying on us to scan social media or listen to the radio to find out we are getting cut off has left me baffled.

‘I only found out because my neighbour who has lived here for 90 years told me, and knew the history of the weir and local infrastructure, and noticed this in the water strategy plans......

Echo, Letters to the Editor, Losing town water access,13 July 2024:

I grew up and live in Mullumbimby, and I know locals have a strong opinion about the Byron Shire Council. I had always given them the benefit of the doubt – as it’s not an easy job. But last week I changed my mind.

Our neighbour, Ray Musgrave, alerted us and other neighbours we’d be losing town water access on our properties. At first, I thought this was simply the Mullum rumour mill, but I called around at Council and found out it was true. Without any doorknocks, phone calls, or letters, we found out dozens of residents at the bottom of Wilsons Creek, including us, would lose town water access if Mullum is connected to Rous water.

While this decision has not been officially made by Council – yet – we all know it is the likely decision. I work in media and communications, sometimes as a consultant for state and federal government, and I’ll admit that tactics are sometimes a little underhanded, but, when it comes to infrastructure and impacting households like this, there would always be doorknocks to every home at a minimum in the communications plan. So, I’m simply shocked at these sneaky tactics by our local council.

Luckily, we have all been neighbours for decades or generations here and were able to quickly agree to work together to try and save our town water. Wish us luck!

Casey Fung, Wilsons Creek

According to the Byron Shire Council website as of 15 July 2024:

Regional water supply

All urban areas in Byron Shire are supplied water from Rocky Creek Dam, which is managed by Rous County Council.

Mullumbimby is supplied from Council's Lavertys Gap Weir.

Rous County Council supplies drinking water to seven reservoirs in the Byron Shire Council from the Nightcap Water Treatment Plant.

Under the Water Supply Agreement, we are responsible for maintaining water quality in the reservoirs and reticulation system......

The Mullumbimby Water Treatment Plant provides treated, filtered, and disinfected drinking water to Mullumbimby.

The drinking water supply is sourced from Wilsons Creek via the Lavertys Gap Weir.

Water flows to the plant by gravity through a heritage-listed race, via a mountain tunnel.

Council documents indicate approximately 13 properties along Wilsons Creek Road are connected to the trunk main from the water treatment plant.

The preferred option of council staff coincides with advice contained in a Hydrosphere Consulting Pty Ltd report (updated May 2024) which clearly stated in 12.4 Option 4 - Full Connection to RCC Regional Supply:

The customers along the Wilsons Creek Road trunk main would not be serviced with this arrangement.

In an alternative scenario within Option 4 Hydro Consulting suggested an Option 4B - emergency connection to regional supply:

As an alternative, the existing RCC emergency supply pipeline could be extended to service the remaining areas of Mullumbimby as an emergency supply only. BSC would then retain Lavertys Gap Weir and WTP as the normal supply regime with future augmentation with another raw water supply source. The customers along the Wilsons Creek Road trunk main would still be serviced by the weir supply and WTP if there was sufficient water in the weir storage. [my yellow highlighting]

However, Byron Shire Council on its public exhibition webpage did not immediately draw attention to the fact that some properties may lose a reliable long-term connection to town water. 

In the first instance it presented the case thus, with the fate of Wilsons Creek Road concealed in webpage links:

Mullumbimby’s water supply scenarios

The consultant’s report short-listed four water supply scenarios, summarised below.

Each scenario has associated benefits and costs.

Council’s engineering staff recommend Scenario 3 – permanent connection to the Rous County Council water supply.

For each scenario, some factors remain the same, including:

• continued use of the weir and Water Treatment Plant (WTP) in the short term

• short-term WTP upgrades to ensure consistent, safe water supply

• extension of the Rous County Council emergency bulk water supply connection to all of Mullumbimby.

Indeed within its boasting about the benefits of what it calls "Scenario 3" it is clear that the potential loss of a long-term reliable town water supply for 30 shire residents & ratepayers is a short-term cost cutting measure.

Scenario 3 – Full connection to Rous County Council

Rous County Council is the regional water supply authority for the Byron Shire, with the exception of Mullumbimby.

Rous also supplies:

• Ballina Shire

• Lismore Shire

• Richmond Valley Shire.

Permanent connection to the Rous regional water supply would mean that water is no longer sourced from Lavertys Gap weir and the Mullumbimby water treatment plant (WTP).

As a result, there would be no need to build a new WTP at Mullumbimby.

Permanent, full connection to the regional water supply is the option recommended by the consultants and Byron Shire Council staff based on the environmental, economic and social assessment.

Benefits of full connection

Connecting to the regional supply has significant benefits over local supply scenarios. [my yellow highlighting]

Full connection offers:

• minimal environmental impact

• lower energy consumption

• reduced infrastructure modifications.

There are significant capital cost savings in avoiding the need to replace the WTP and upgrade the weir supply in addition to constructing new infrastructure. However, the ongoing costs of a regional supply are higher than local scenarios. [my yellow highlighting]

Permanent connection to the regional supply means Mullumbimby’s long-term water security is determined by Rous County Council's bulk supply system, as is the case for the rest of Byron Shire.

Byron Shire Council is scheduled to decide on its water supply strategy at its August monthly meeting.

Yet another Clarence Valley development application with wet feet?

 

MASTER PLAN
DA 2023/0711
Click on all images to enlarge

Clarence Valley Independent, 20 December 2023:

A development application DA 2023/0711 for a $6.65 million 95 lot manufactured home estate at South Grafton is currently being assessed by Clarence Valley Council and submissions from the public are invited.

The DA lodged by John Codling is for the demolition of existing buildings at 252 to 298 Rushforth Road and construction of a 95 dwelling manufactured home estate, a community building, a 25m by 10m swimming pool, children’s play area, community gardens, recreation areas and community title subdivision.

The Statement of Environmental Effects SEE, lodged with the DA states the 95 home manufactured housing estate will take up 8.57 hectares of the 11.54-hectare property, with proposed residential sites varying from 282 square metres to 450 square metres.

The Manufactured Home estate will be located on the southern and eastern portions of the property, with the northern and western areas remaining unimpacted by construction.

“The proposed large community clubhouse, centrally located at the entrance to the development, will act as an indoor and outdoor meeting place for residents of the estate and their visitors,” the SEE states.

“The proposed dwelling sites and community facilities will be set in a landscaped environment supported by recreational facilities.”......

Sounds like low income retirees heaven, doesn't it?

Until one realises that an existing wide drainage channel easement dissects the planned manufactured home estate and discharges into what appears to be marshland and creek. Which sets the mind a-wondering.

From there it is easy to discover that the entire manufactured home estate on that lot will be directly in the path of the maximum possible Clarence River flood (based on probable maximum precipitation) according to Clarence Valley Council 2022 flood modelling.

Clarence River very dark blue, 1 in 100 probability in any given year for a flood event is coloured darker blue and, the full range of a maximum probability flood coloured light blue with est. 11.5 ha DA site in dark red.

IMAGE: https://maps.clarence.nsw.gov.au/intramaps910/

In addition the "Stormwater Management Plan & Preliminary Flood Assessment" (17 October 2023) at Page 10 supports this view and adds another dimension:

2. The subject site is subject to Clarence River flooding during an ‘extreme event’. This is limited to the northeastern portion of the site (Figure 4).....

5. The entire site is subject to flooding during a Probable Maximum Flood (PMF) event (Figure 8). Depth and velocity information is not available.

6. Site inundation due to 1:100 storm event runoff from the Rushforth Reservoir (Figure 9) is similar but of a lesser extent than what is mapped as fluvial inundation (Figure 5). Nine lots are affected by shallow (<0.2m) inundation (Figure 11).

7. A Rushforth Reservoir dam break would inundated a large component of the northeastern site precinct (Figure 10). The inundation depth in the northeastern part of the site where the lots are is generally below 0.5 metres (Figure 12), but it increases to 0.8 metres along the eastern site boundary (past the lots).

The developer cannot fail to be aware that the site will experience everything from episodic, low-level nuisance flooding from the creek to a probable maximum full inundation from the river 13.6-13.7m in height potentially sending on a conservative calculation 0.6-3.8m or somewhere between 2-12 feet of rushing water though the manufactured home estate.

Bottom line is that the next time climate change throws a record breaking Clarence River flood at valley communities, South Grafton will possibly have another 190+ people to evacuate to higher ground - as is advised at Page 18 of the developer's document "Stormwater Management Plan & Preliminary Flood Assessment". 

Not sounding quite as attractive now, does it?

SEE FULL DETAILS AT: https://cvc-web.t1cloud.com/T1PRDefault/WebApps/eProperty/P1/eTrack/eTrackApplicationDetails.aspx?r=CVC.P1.WEBGUEST&f=%24P1.ETR.APPDET.VIW&ApplicationId=DA2023%2f0711

27 days out from the beginning of the 2023 Australian Summer and drought intensifies in Northern Rivers region

 

By 30 October 2023 NSW Dept. of Primary Industries' Combined Drought Indicator mapping showed that drought was intensifying along the North Coast of the state, from Port Macquarie-Hastings up to the NSW-Qld border. 

NSW DPI Combined Drought Indicator mapping, 30 October 2023
Click on image to enlarge

 An est. 42.8% of the region is experiencing intense drought; with another est. 41.6% in drought; and 15.5% considered drought affected.

As of the end of October, the North Coast region was the most affected by the growing drought conditions. State-wide almost half the land area is yet to experience drought. With only est. 3.2% of the total land area listed as in intense drought; est. 13.8% in drought; est. 33.8% drought affected; and the remaining 49.2% unaffected by drought conditions. 

Recent drought history from January 2017 to October 2023 of three Clarence Valley parishes which include major population centres.

Click on images to enlarge

Clarence Valley Council, News, 31 October 2023:

Clarence Valley community urged to reduce water use

A combination of low rainfall and high consumption has put Clarence Valley on the brink of water restrictions.

Due to low flow conditions in the Nymboida River, Clarence Valley's water supply is currently being sourced from Shannon Creek Dam.

Clarence Valley Council has Permanent Water Conservation Measures in place. However, dry conditions are predicted to continue and current projections indicate water restrictions are likely in the near future.

Several neighbouring councils have already implemented water restrictions including Bellingen Shire and parts of Tweed Shire, while Rous County Council, which services Ballina, Byron, Lismore and Richmond Valley, anticipates Level One water restrictions will be activated before Christmas.

"It is now an important time for the community to make a concerted effort to adhere to the permanent water conservation measures in order to delay the introduction of water restrictions," CVC Manager Water/Sewer Operations Andrew Potter said.

"Water consumption across the Clarence Valley has steadily risen in recent weeks, including several days above capacity."

The Rushforth Road Water Treatment Plant (RRWTP) has maximum capacity to provide 22 megalitres per day. Average daily consumption (22.39ML/day) exceeded 22ML for the first time in the week ending Sunday 22 October, when consumption peaked at 28.01ML.

There have been another ten days of more than 22ML being pumped out of RRWTP since 21 September, when temperatures reached 37 degrees for the first time heading into the warmer months.

"Generally warmer weather correlates with higher water consumption," Mr Potter said.

"We understand people are keen to keep their lawns and gardens alive. However, we urge people to consider ways they can reduce their usage….

Tweed Shire expects to start rolling out water restrictions within next few weeks and rest of the Northern Rivers region likely to be following its lead sooner rather than later

NSWDPI Combined Drought Indicator (CDI) mapping, 23 September 2023. CDI = Combined Drought Indicator. RI = Rainfall Index. SWI = Soil Water Index. PGI = Pasture Growth Index. DDI = Drought Direction Index

Click on map to enlarge

There are 19 large dams on NSW regional regulated rivers and hundreds of smaller dams, reservoirs & weirs associated with a mix of environmental use, off-farm agricultural and urban water storage on other rivers.

Across the seven local government areas in the Northern Rivers region water storage locations include:

Toonumbar Dam

Rocky Creek Dam

Clarrie Hall Dam

Emmigrant Creek Dam

Korrumbyn Creek Dam

Shannon Creek Dam

Bray Park weir

Tyalgum weir

Mullumbimby Power Station weir

Jambour weir

Kyogle weir

Nymboida weir

Rushforth Road 100ML Reservoir.

Tweed Shire Council is strongly alerting its residents and ratepayers as to the current situation and what may lie ahead.

The Echo, 27 September 2023:

Following the devastating floods of 2022 we are back to dry weather. The Bureau of Meteorology (BOM) has declared an El Nino weather pattern and it has predicted that there will be less-than-average rainfall in the Northern Rivers this year. Tweed Council is reminding residents and visitors that it is important to save water as we head into dry weather.

‘Without significant rain, the Tweed will head into water restrictions, with restrictions for Tyalgum looking likely in the next few weeks,’ said Tweed Shire Council’s (TSC) water and wastewater business and assets manager Michael Wraight.

‘We source our water from the Tweed River at Bray Park and Uki, plus the Oxley River at Tyalgum. The river flows are down and the weir pools at Bray Park and Tyalgum are drying up.

‘While Clarrie Hall Dam is currently sitting at 98 per cent capacity, it will now drop about 1 to 1.5 per cent, per week, as we start releasing water to supply the Bray Park Weir – the source of water for most of the Shire.

‘We will trigger level 1 water restrictions when the Clarrie Hall Dam level drops to 85 per cent.

‘Restrictions at Tyalgum will be introduced sooner. The flow of the Oxley River at Tyalgum is down to a trickle and the weir pool there is dropping fast.’

Loss of soil moisture and drought conditions continue to grow across New South Wales in September 2023

 

NSW DPI COMBINED DROUGHT INDICATOR MAPPING

Click on image to enlarge

Data current to 10/9/2023 (AEST)

CDI = Combined Drought Indicator. RI = Rainfall Index. SWI = Soil Water Index. PGI = Pasture Growth Index. DDI = Drought Direction Index

NOTE: The CDI and its individual rainfall, soil moisture and crop/pasture growth metrics are leading biophysical indices of seasonal conditions and drought status. Other factors affecting production and economic responses usually lag the CDI.

From Hastings/Port Macquarie up to the NSW-Qld border 78.7% of the North Coast is Drought Affected and 9.2% In Drought. Only 12.1% is currently considered unaffected by drought.

Water NSW: regional water storage levels as of 14 September 2023

Updates can be found at https://www.waternsw.com.au/nsw-dams/nsw-storage-levels/regional-nsw-dam-levels

According to the NSW Department of Primary Industries, end August 2023:

Drought conditions are continuing to expand and intensify on the North Coast, Northern Tablelands, Hunter and the South East Local Land Services (LLS) Regions of NSW. These conditions are consistent with the onset of a major drought in these regions, and the drought indicators show that the area of this event is growing across the Northern Tablelands and North-West. Producers are continuing to monitor on-ground conditions and climate forecasts closely, while implementing actions in line with their individual drought strategies.

Seasonal Climate Outlook

Seasonal climate forecasts indicate increased likelihood of warmer than average daytime and overnight temperatures for most of NSW for the September to November period.

Rainfall has an increased likelihood of being below average to well below average for most of NSW for the next three months.

The ENSO Outlook status remains at El Niño ALERT. When El Niño ALERT criteria have been met in the past, an El Niño event has developed around 70% of the time.

The Indian Ocean Dipole (IOD) is currently positive

So this Australian Winter was expected to be drier and warmer than the median mark, but now it seems twice as likely a rainfall suppressing El Niño event will also start this year

During the multi-year Millennium Drought from 1997 to 2010, south east Australia experienced its lowest 13-year rainfall record since 1865 over the years 2006 to 2010.

Temperatures were also much hotter than in previous droughts and temperature extremes peaked during the heatwave and bushfires in early 2009. This culminated in the loss of 374 lives in Victoria and many more over the larger southeast in the heatwave leading up to Black Saturday. There were 173 lives lost in the fires.

The years 2015 to 2016 saw El Niño combined with a positive Indian Ocean Dipole in the second half of 2015 further suppressing rainfall, so that rainfall was the equal fourth-lowest on record for Australia during September, Tasmania had its driest Spring on record and mean temperatures were also highest on record for October to December 2015. This El Niño also contributed to an early start to the 2015-16 southern fire season.

By 2017 Australia was again in the grips of a multi-year drought. Very dry conditions in the cool season were followed by only a limited recovery in the October–December period in 2017 and 2018. This meant record-low rainfalls over various multi-year periods.

By June 2018 more than 99% of NSW was declared as affected by drought. The most extreme rainfall deficiencies over multi-year periods occurring in the northern half of New South Wales.

In June-July 2019 New South Wales began a trial by mega bushfires, as did other east coast states, that lasted through to January 2020.

Widespread drought was not an issue for the remainder of 2020 through to the present day, given La Niña visited three times in three years bringing high rainfall events and record floods in the eastern states.

However, the Australian Dept. of Agriculture, Forestry and Fisheries (ABARE) is now drawing attention to this:

All but one international climate model surveyed by the Australian Bureau of Meteorology suggest sea-surface temperatures in the tropical Pacific will exceed El Niño thresholds in June. [ABARES Weekly Australian Climate, Water and Agricultural Update, 25 May 2023] 

[ABARES, 25 May 2023] Click on image to enlarge

Suggesting in its climate update that there is now twice the risk of an El Niño event this year, with a likelihood of it making itself felt sometime between August and October.

The overall outlook for this Australian Winter continues to be below median rainfall and warmer median temperatures. 

The main urban centres in the Clarence Valley have a chance of unusually warm temperatures over the winter months of between est. 55-60% (Maclean-Yamba-Iluka) and 59-65% (Grafton). While elsewhere in the Northern Rivers region unusually warm temperatures are expected in Lismore with est. 58-59% chance, Tweed Heads est. 59-62% chance, with Byron Bay & Ballina at est. 60-61% chance. [BOM, Climate outlooks—weeks, months and seasons, June-September 2023]

How this developing scenario affects agricultural growing seasons over the next twelve months is anyone's guess.

In New South Wales only the parishes of Newbold and Braylesford in the Clarence Valley are showing Combined Drought Indicator (CDI) at “Drought Affected”. 

Nevertheless, root-zone soil moisture has been falling across north-east NSW so that by end of April 2023 it was very much below average in from the coast. 

Remembering that drought 'safety net' Shannon Creek Dam, which supplies urban town water to both Coffs Harbour City and Clarence Valley resident populations (total 134,538 persons, June 2022) is currently at 92.6% capacity or 27,677 megalitres, perhaps we may see increased water restrictions by the next Christmas-New Year period. Given the tourist-driven seasonal population rise increases water consumption and that 80% dam capacity is the increased restrictions trigger.

It doesn't take a genius to suspect that should a drought develop, the 2024 and 2025 bush fire seasons might also be highly problematic for rural and regional areas across Australia.