A NSW government grant of $450,000 has been awarded for the sinking of a test bore at Yarrie Lake to assess the feasibility of using a bore as a top up source of water for the lake. Below, a letter from the Yarrie Lake Flora and Fauna Trust to Yarrie Lake Bore Committee, care of Narrabri Chamber of Commerce, outlining the trust’s views on the proposal:

We advise the trust met on September 22 and discussed the issue of the test bore.

The trust resolved that there are a number of critical questions that remain unanswered and that these questions need to be properly addressed and answered before a test bore is commenced.

In particular the trust must consider issues of an environmental nature, particularly in circumstances where there is significant and active objection from surrounding landowners to the project proceeding.

The trust feels that the proposal needs to be put on a professional footing, and that ultimately this can only be done with a feasibility study being completed by a suitable qualified organisation.

You will be aware that the trust first raised in writing with you the need for a feasibility study on November 12, 2017, and again on June 28, 2018 and on October 29, 2018.

The strong objection to the project by surrounding landowners (evidenced by Anne Cain’s recent letter to the editor) as expressed to the trust make it clear that the trust must be assured that the project can be feasible if a suitable bore supply is found.

The matters the trust would propose need to be addressed in a feasibility study include, but are not limited to, the following:

1. Salt accumulation in Yarrie Lake

It is likely that there will be an increase in the salinity level in Yarrie Lake as a result of bore water being pumped into the lake and then evaporated off – leaving the salt behind.

A 2017 hydrogeological report commissioned by the trust suggested the salt level in the nine bores in the immediate area of Yarrie Lake had salinity levels ranging from ‘fresh’ (0-500ppm) to 500-1000ppm.

The trust needs to know the effect on the Yarrie Lake salinity of pumping 150 megs of bore (salty) water into the lake.

For instance – after five years (750 megs) what will be the increase in salinity assuming bore salinity modelled at 500ppm and 1000ppm?

2. Placing bore water into a waterway

The natural fall of the land is such that Yarrie Lake fills by overland flows from the south, and once full, discharges to the north.

The view of the trust is that Yarrie Lake is part of a waterway.

The lake is fed, in part, by an unnamed ephemeral stream which crosses Hibbens Lane one km west of the Nuable Road/Hibbens Lane intersection.

This unnamed ephemeral stream runs south to north across two lots before discharging into Yarrie Lake.

A further unnamed ephemeral stream crosses Smith’s Lane at a point some 190m east of the Nuable Road/Smith’s Lane intersection, before discharging into Yarrie Lake after flowing across another lot).

A further unnamed ephemeral stream crosses Smith’s Lane at a point some 2km east of Nuable Road/Smith’s Lane intersection before flowing across a further Lot and discharging into Yarrie Lake. Even more significantly, the overflow from Yarrie Lake discharges into Illaroo Creek 2.2km north of Yarrie Lake.

In flood events the overflow from Yarrie Lake also flow to the north-west in an unnamed ephemeral waterway which flows over Lot 22/757120.

There are at least three specific waterways which run water into Yarrie Lake and at least two which accommodate overflow – one of which flows directly into Illaroo Creek.

The trust needs to know whether bore water is permitted to be discharged into the waterway.

3. Evaporation Losses

It is the trust’s understanding that evaporation losses from Yarrie Lake range from a low of 30l/sec in winter to > 200 litres/sec in summer. The Tahlee Report commissioned by the fundraising committee is helpful in relation to understanding evaporation loss and the benefit in terms of additional days the lake would be available for use. The feasibility study should review the Tahlee Report and address generally the issue of evaporation loss.

4. Prospects of a suitable supply being available at the location

A report provided by experienced hydrogeologists in October 2017 suggests there are very limited prospects of a suitable groundwater supply being found.

The report should be reviewed as part of the feasibility study and information provided to the trust as to the predicted availability of a suitable supply.

It is noted by the trust that it has been suggested that a recently drilled bore on a nearby property was free flowing.

The trust contacted the owner who indicated the bore in question free flowed for a short time (hours) but was extremely salty to the extent that it had to be capped and abandoned.

5. Pumping Logistics and Costs

If a suitable bore supply was to be located the issue of how it would be brought to the surface is a critical issue.

There are suggestions that a suitable bore would be free flowing, however this contention is not supported by the hydrogeological report or by the anecdotal evidence – noting that there are no known (to the trust) free flowing bores in the area.

The feasibility study needs to address this issue and provide factual information, modelling for a number of depths – perhaps 400m and 1000m.

6. Ongoing costs including Water Licence purchase and annual water purchase

The trust understands that should a suitable supply be obtained, there will be costs associated with purchasing a water licence and with the annual cost of the water.

These costs are not known to the trust and should be included in the feasibility study.

7. Overuse of the resource

Whilst not necessarily a matter for a feasibility study, it should be noted that the trust itself has very limited income sources.

The trust has steadfastly indicated that it does not wish to turn the Yarrie Lake Reserve into a commercial venture as it will lose its unique character.

The trust has sought to ensure that the bush camping aspect of Yarrie Lake is maintained – noting that the capacity of the lake, in terms of boat numbers and/or camping spots is very limited.

In 2016 when the lake was full for consecutive years, the number of boating permits issued by the trust quickly went over 150, and at those numbers the lake was bursting at the seams on long weekends and school holidays.

In the event that numbers again get much beyond the 2016 level, the trust may have no alternative then to look at options to limit or restrict user numbers.

8. Bore placement

The trust has been told differing things as to where a test bore can be drilled.

It has been suggested by your group that the test bore is required to be 200m from the lake, as well as 200m from any building or private property including the septic tank discharge. The trust has tried to locate a test bore site which meets the 200m rule and it appears there is some difficulty finding a site.

This issue needs to be addressed and the trust provided with accurate information regarding rules around placement.

9. Summary

The trust is in a difficult position, with your group keen to go straight to a test bore, but with much concern being raised in the community.

The trust’s view is that the balanced approach would be to have a feasibility study done as the first step and should the study not raise any environmental or statutory issues, then the test bore would be step two. In the event that your committee agrees that a feasibility study is to be the next step, the trust would ask that it sign off on any brief proposed to be given to the proposed consultant.

If necessary, the trust is happy to provide a draft brief for your consideration.

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