I’ve spoken to a lot of people about the recent flooding in the Hawkesbury-Nepean Valley and many are saying ‘Thank God the dam wasn’t full’.

With Level 2 water restrictions in place for Sydney since being enforced late last year due to Warragamba Dam levels being the lowest that they have been in 15 years (prior to this week’s rainfall), as of today, the Water NSW data for Warragamba Dam showed…

Storage (recorded date) Wednesday 12 February

Warragamba Dam

Storage Capacity - 2,027,000 megalitres

Current Volume - 1,445,974 megalitres

Percent Full - 71.3%

Net Change in past week - 28.5%

Back on the 24th July 2019, I attended a meeting held by Hawkesbury-Nepean Valley Flood Mitigation Committee as a member and representative on behalf of Windsor Downs residents.

Alison White, Manager Communications and Engagement, Hawkesbury-Nepean Flood Strategy from Infrastructure NSW presented on numerous issues regarding the Hawkesbury-Nepean Flood Risk Management Strategy including evacuation strategy, plans for raising flood awareness along with the Environmental Impact Study (EIS) for the raising of Warragamba Dam wall to allow the dam to be used for flood mitigation. (the EIS is soon to be released for public comment)

During the meeting I raised several issues:

- The impacts of surrounding development areas on flooding & evacuation
- How do Infrastructure NSW expect to evacuate thousands of extra people during floods when Richmond Road is currently inadequate for moving traffic during peak times
- Would raising the dam wall reduce the current exorbitantly inflated flood cover insurance premiums some of the insurance companies are charging

So what happened since that meeting ahead of this week’s floods:

There was a regional flood study released and an extensive ‘Get Ready’ campaign was rolled out back in September/October 2019 ahead of the Summer storm season, which was designed to raise awareness about flooding in the Hawkesbury-Nepean Valley along with flood-evacuation route sign posting was installed throughout the district.

Also, this video was released via the SES website explaining the bathtub effect.

When the EIS is released later this year there will be an excellent opportunity for residents living in the Hawkesbury-Nepean Valley to have your say.

Once the rainfall within the Warragamba Dam catchment ceases, it will be very interesting to see how accurate the flood modelling predictions were when compared to what actually happened.

There are currently a lot of myths being thrown around regarding impacts and extra development.

People saying that raising the dam wall will open up more land for development below the current 1:100 flood level may not be aware that the plan is not to lower the levels for future development as this will only recreate the same threat.

There has already been some responsible Backzoning done which changed the Penrith LEP to stop approximately 5,000 homes from being built around Penrith Lakes Scheme due to evacuation issues.

Even future land development on some of the properties situated above the 1:100 will be assessed based upon the developments’ impacts on evacuation.

Also, the proposal to raise the dam wall is not so that Water NSW can increase the water storage for Sydney’s growing population.

If the proposed future dam with the extra 14 metre high wall is then allowed to be filled up to provide a greater water supply capacity, then it would defeat the whole purpose of being a flood mitigation dam and it wouldn’t be able to hold back the water during heavy rainfall like Warragamba Dam fortunately did to reduce the scale of the flood devastation for thousands living downstream of the dam this week.

People saying ‘Thank God the dam wasn’t full’ doesn’t diminish any of our thoughts about those people who have been impacted by the recent floods and respectfully it is terrible to see the number of families, properties and businesses that were impacted by these recent floods and my heart goes out to all who have been caught in the midst of this disaster.

The EIS will hopefully be considered responsibly by Government and Local Councils because naturally there are going to be impacts both upstream & downstream to consider.

Until the EIS comes out, at present all one can say is we feel for all of those who have been impacted and thank heavens that Mother Nature went a bit easier on us this time around as in a worst-case scenario (imagining that the dam was full before this week’s rain), over 500,000 megalitres of extra water would have flowed downstream into the Hawkesbury-Nepean Valley, which would’ve been even more catastrophic with flood levels rising faster and reaching heights not seen in over a century.

My thoughts and prayers are with all of those families impacted by the recent floods, the devastation, the evacuation, displacement of family & animals, the increased level of frustration and uncertainty which happens during the floods along with the massive clean-up after the flood waters disperse. It’s a horrible (smelly) job.

I wish you all the very best and sincerely hope that this is the last of the flooding that we will see in our area for quite a while.

Regards

Greg Vincent