Otway Ranges Environment Network

 

 

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7. DOMESTIC WATER SUPPLY


Logging industry propaganda

  1. Logging has no impact/ negligible impact on water supply. Link

  2. Water restrictions are/where caused by drought not logging. Link

  3. Research by Sinclair Knight Merz(SMZ) shows logging has no impact on current water yield from forest. In fact it may still rise slowly. Link

  4. SKM Research shows logging in water catchments involves Best Management Practices (BMP). Link

  5. The biggest impacts on water catchments are agriculture and urbanisation. Link

  6. Half the Gellibrand catchment is private land for which agriculture and urbanisation are the biggest threats to water not logging. Link

  7. Measures are in place to prevent landslides in the Otways. Link

  8. Wild fire is the greatest risk to catchments not logging. Catchment areas burn so regularly that it is unlikely they will ever reach a state of old forest and high water yield. Link

  9. There is a 200 meter buffer applied around water storage's to protect dams. Link

  10. Water yield will increase by an average of 6% per annum not 10%. Link

Brief Response

1. Logging has no impact/ negligible impact on water supply.

  • It has been scientifically proved that the age of a forest impacts on the amount of water run off. Young vigorously growing trees that grow after clearfell logging in wet forests can reduce the quantity of water run-off into catchments. See Kuczera curve.

  • Independent research released by Sinclair Knight Merz Research in 2001 shows that if clearfell logging in the Otways ended in the West Barwon Catchment or Arkins Creek catchment, water run off would increase by 10% and 28% respectively.

  • A 10% increase in water runoff from the West Barwon dam is equivalent to the water consumption of city of 10,000 people. See link.

2. Water restrictions are/where caused by drought not logging

  • The comment "water restrictions are caused by drought" is irrelevant to the debate about the impact of clearfell logging on water yield. The fact that there where four years of water restrictions in the Geelong region (1997-2001) simply helped focus the community on the issues surrounding water availability for domestic use and the impact logging has on water supply.

3. Research by Sinclair Knight Merz(SMZ) shows logging has no impact on current water yield from forest. In fact it may still rise slowly.

Three scenarios were investigated by SKM into the impacts of logging on water runoff in the Otways. These were:

1. no-logging.
2. currently levels of logging proposed under the RFA.
3. 50% of the catchment burnt by a bushfire.

These three scenarios were applied to West Barwon catchment and Arkins creek areas.

The statement "logging has no impact on current water yield from forest" only refers to scenario No.2 and ignores other possible futures offered by scenario No.1 and No.3.

4. SKM Research shows logging in water catchments involves Best Management Practices (BMP).

BMPs are practices designed to protect or minimise the impact of logging practices on soil and water values. Such practices outlined in the Code of Forest Practices and Otway Forest Management Plan include retaining forested buffer strips along streams, no logging over 30 degrees, location and rehabilitation of log landings sites and the design and location of logging roads.

The SKM research acknowledged that measures outlined in the Code of Forest Practices are generally implemented in the Otways , however:

1. it is not known how effective these measures actually are to protect of soil and water values. SKM referred to the lack of research into the effectiveness of BMPs across Victoria. See SKM page 85.

2. SKM highlighted a lack of prescriptions required to identify or response to landslides risks caused primarily by logging roads in the Otways.
Note: landslides were called "mass movement hazard" by SKM.

5. The biggest impacts on water catchments are agriculture and urbanisation.

  • The catchments for Geelong, Apollo Bay and Lorne do not have any agriculture or urbanisation in their headwaters. The headwaters are predominantly native forest. Hence for these catchments, the issue of agriculture and urbanisation is irrelevant.

  • The issues regarding agriculture and urbanisation are only partly relevant to the Gellibrand catchment. About 56% of the Gellibrand is public land with native vegetation. Overall, 70% of the Gellibrand catchment is still forested. See Gellibrand land use.

6. Half the Gellibrand catchment is private land for which agriculture and urbanisation are the biggest threats to water not logging.

  • The Gellibrand proclaimed catchment area(66,570 ha) is mostly a forested catchment with 70% native forest. About 17% is cleared agricultural land and 13% is plantations (mostly radiata pine). The majority of the high rainfall/recharge areas still have native forest with about 80% of the cleared agricultural land located in the valley of the Gellibrand river which has a lower rainfall. See Gellibrand land use.

  • Urban impacts within the Gellibrand catchment are small and classed as light urban. There are only small towns within the catchment that include Carlisle, Gellibrand, and parts of Lavers Hill and Beach Forrest.

  • Clearfell logging practices add another level of disturbance and risk to water values already under stress from private land users.

  • Stopping logging on the significant public land component of the Gellibrand catchment will improve summer flow reliability when domestic consumption from Warrnambool and the Dairy Industry is at its highest. See Gellibrand river summer flow vulnerability.

7. Measures are in place to prevent landslides in the Otways.

  • There are no prescriptions to prevent logging induced landslides in the Otways. This includes nothing in the Code of Forest Practices for Timber Production or the Otway Forest Management Plan.
    Note: landslides were called "mass movement hazard" by SKM.
    See lack of landslide prescriptions.

  • High rainfall events are a major cause of landslides and water degradation associated with logging practices. An example of this occurred at HP track in November 1995[water\22landslides.htm]. Despite this, there is little research being conducted.[ water\25rainlandslide.htm]

8. Wild fire is the greatest risk to catchments not logging. Catchment areas burn so regularly that it is unlikely they will ever reach a state of old forest and high water yield.

  • It is a myth that wet forests that have evolved in high rainfall areas have high tendency to burn. Research highlightes the fact that wet Otway forest are not a fire prone environment. In fact catchments that have never been disturbed by logging such as Olangolah (Colac's water supply) contain forest that is over 150 years old.
    See Fire Occurrence in Otway Catchments.


  • Forestry Victoria have hypocritically contradicted themselves regarding their claims on fire frequency in propaganda documents released to the public. The contradiction basically implies a wildfire can discriminate between forest available for clearfell logging in catchment areas and forest protect in reserves..

  • This Forestry Victoria fire contradiction adds weigh to the argument that logging practices are making wet forest more fire prone in catchment areas and hence increasing the risk of major reductions in water yields.
    See Clearfell logging is making the wet forests of the Otways drier and more fire prone

9. There is a 200 meter buffer applied around water storage's to protect dams.

  • Clearfell logging occurred within 200 metres of the West Barwon Dam high water mark in 1997. This was a clear breach of the Otways Forest Management Plan and has been acknowledged by Barwon Water.
    See Logging within 200 metres of West Barwon.

10. Water yield will increase by an average of 6% per annum not 10%.

  • This use of averages to determine the increase in water yield if logging was is stopped misrepresents the magnitude of water yield gains that can be achieved. If logging was stopped in the West Barwon catchment, it will take 60 years to achieve a 10% increase in water run off and it will stay at approximately 10% more for decades or centuries after.
    See Kuczera Curve
    See West Barwon catchment
 
   
 
 

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