Parliamentary Committees

Public Works Committee: Patawalonga South Gates Upgrade

Mr BROWN (Florey) (11:01): I move:

That the second report of the committee for the Fifty-Fifth Parliament, entitled Patawalonga South Gates Upgrade, be noted.

The proposed works are the upgrade of the south gates in the Patawalonga Lake system located in Glenelg North. These gates retain the water level within the lake system and keep the natural banks submerged. They maintain water quality and support marine life whilst allowing recreational use of the water and safe harbour of boats and other vessels. The original south gates structure was built in the 1950s and consisted of five gates and a lock. Since that time, a number of additional works have been completed.

The current eight gates are made from steel that shows signs of corrosion, and the deterioration will continue over time. Due to the south gates' poor condition, most of the operating budget goes to the repair of breakdowns, which limits the funds available for preventative maintenance. The proposed works will replace the five gates in the worst condition as well as install electrical panels, a new drive train and local control to all gates.

It is clear that a healthy, functional lake system is vital to the quality of life of residents. Upgraded gates would benefit not only these residents but also the many tourists and visitors who enjoy the iconic shoreline all year round. Proper functioning of the south gates is therefore needed to support the short and long-term economic interests of the region and the state.

The overarching goals of these public works are the efficient management of stormwater and the maintenance of a safe and healthy lake system. This project will protect the health of this ecosystem well into the future and minimise the threat of flooding to surrounding suburbs. It presents a long-term, cost-effective and operationally efficient solution for the Department for Environment and Water. The estimated capital cost of the south gates upgrade is $6.1 million. Construction is scheduled to commence in December 2022, with the work completed in June 2023.

The Public Works Committee has examined written and oral evidence in relation to the Patawalonga south gates upgrade. The committee is satisfied that the proposal has been subject to the appropriate agency consultation and meets the criteria for examination of projects as set out in the Parliamentary Committees Act 1991. Based upon the evidence considered and pursuant to section 12C of the Parliamentary Committees Act 1991, the Public Works Committee reports to parliament that it recommends the proposed public works.

Mr PATTERSON (Morphett) (11:04): I also take the opportunity in parliament today to speak about this important report from the Public Works Committee regarding the Patawalonga south gates upgrade. These gates are the southern gates in the Patawalonga Lake system, which is in Glenelg North, which is of course in the electorate of Morphett. It involves replacing five of the weir gates.

It is very important not only to those in the Glenelg North community but to Glenelg as well. They probably see it importantly as a key linkage between the Glenelg North peninsula and the busy Glenelg Jetty Road precinct. It provides a walkway between these two great communities, really connecting them together. As I said, it is about a kilometre north of Jetty Road, which of course many people like to visit, especially on the weekend.

Additionally, you have the fantastic Coast Park throughout most of our metropolitan beaches and certainly through the electorate of Morphett, going from Somerton Park, all the way through Glenelg and up to Glenelg North. Many people on their walks or runs or even rides use this walkway made by the weir gates. If that weir gate or the connector were not there, the other option would have to be to go along the Patawalonga Lake system and over the Michael Herbert Bridge, so you can see how important it is. That adds kilometres onto the trip, and I will touch on that a little bit later in my submission.

Fundamentally, what this upgrade will be about is the health of the Patawalonga Lake system and also flood mitigation to help protect many of the surrounding houses. Before the weir was built, certainly in pre-European settlement days, the Patawalonga itself was, of course, an estuary. In fact, it was the first place where the initial fleet that came here—the Buffalo and the Cygnet—located fresh water as they went up the coast. Looking for that, they saw the Patawalonga outlet and realised that there was fresh water here and a potential settlement, which then became Adelaide.

So, from that perspective, at that time it was an estuary surrounded by a lot of sand dunes, which then made its way back through swamps, effectively, to firmer land. In fact, the Old Gum Tree, where we have our Proclamation Day ceremony and where the colony of South Australia was proclaimed, is a fair way inland and the trip was made there following the Patawalonga along into what is now Sturt Creek.

You can see it is a key freshwater system or estuary system and it is in fact really the drain of a lot of our creeks from the Adelaide Hills. We talk about the Adelaide Hills as being a big green island. Of course, that rain has to go somewhere and the way that a lot of those creeks work is that they make their way out to sea via this Patawalonga Lake system.

There are two important tributaries. Brownhill Creek starts in Mitcham. Many will see it as it goes through Unley and down along past Sir Donald Bradman Drive and along the airport. Many will see that creek, or what is really now a big cement drain, make its way along Sir Donald Bradman Drive and along Tapleys Hill Road, before meeting the Patawalonga Lake system near the Glenelg baseball fields.

Joining the Patawalonga system at the same point as another important creek system is the Sturt Creek. It starts its journey in the Hills and then makes its way through my electorate, going through Morphettville, Glengowrie and then Glenelg North. Sturt Creek itself is now lined with concrete, so it effectively allows for a rapid movement of water, which is good to keep water flooding at other points in the Sturt Creek but means that it makes its way into Glenelg quite quickly, which sees a large body of water make its way into the Patawalonga Lake system, meaning there is the very real risk that flooding can occur.

As I said, it was initially an estuary. The storms in 1948, which saw those famous pictures of the Glenelg jetty being destroyed and also significant coastal damage, were the impetus for the weir gate to be set up to help protect this lake system and the coastline, which resulted in the weir gate system being opened in the 1960s. Since then, it has been doing its job, really keeping the Patawalonga Lake levels up, otherwise it would be much more dependent on natural rainfall.

Before these weir gates, one of the other aspects of being able to raise these lake levels is that it also covers the natural riverbanks, which were a source of what was quite an offensive smell, according to reports at the time, so it is another important reason for making sure that these lock gates are maintained to help mitigate those issues. The net result of these elevated wall levels is a terrific amenity for the local community, with wide paths right around the Patawalonga, and it also allows kayaking to occur. In fact, local dolphins make their way up there as well, so there are certainly some spectacular sites in the Patawalonga, so it is very important to the community.

The lake system operates as a tidal system. As the high tide of the ocean occurs, the weir gates are lifted, which allows water to come into the lakes, and then the gates can be closed. On a low tide, through the Barcoo Outlet, it allows for a lower tide and the water to then flow back out again. That keeps it functioning on a day-to-day system. You can see that these weir gates are used not just as a one-off; they are actually used on a regular basis, so their maintenance is important. Unfortunately, a lot of the maintenance at the moment is just repairing rather than preventative. The upgrades for these gates is much welcomed.

I will quickly talk about flooding to show the impacts of flooding. In 2003, there was significant flooding around the Patawalonga because of maintenance issues with the weir gates. It ran into the millions of dollars; some reports have it upwards towards $20 million of damage. The necessity that these weir gates operate effectively you can see and the impact it can have on the surrounding Glenelg North householders.

More recently, in September 2016, a potential big flooding event there coincided with a king tide, which is quite often the case when there are storms and tide lift. As I have explained before, to get water out of the system we need to make sure the water levels in the lake are higher than those at sea. A king tide reverses that. In fact, the water coming down the Sturt Creek was coming at a rapid pace at the same time as a king tide. Luckily, it ebbed at the right time, within an hour or two, otherwise flooding would have occurred. So you can see how important it is that these gates are functional at all times.

If I can touch on the work to be done, it really is important that it be done, and it is welcomed. I was able to present to the committee to make sure that the community is consulted about this. The walkway is important. I emphasised the need to have a temporary walkway for the pedestrianisation to connect the two communities while this is occurring. I believe that to be the case. Importantly, also, those at the lock at the Patawalonga, which allows commercial operators to go in and out, need to be able to continue, so consultation needs to be done with those business operators while cranes are being used to put in place the gates to make sure they can still operate their business, which is really important.

This upgrade is much welcomed. It is $7 million, and that funding is coming from the $4 billion COVID stimulus package provided by the Marshall Liberal government. This project is an important project set up and put underway by the former Marshall Liberal government. It is going to be much welcomed by the community. I am happy that it has been recommended to continue by the committee.

Mr BROWN (Florey) (11:14): I just briefly want to make a correction. It was remiss of me not to point out that member for Morphett had attended the committee hearing on behalf of his local constituents and expressed his support for the project. I want to thank him for coming, and I want to thank the members of the committee for their deliberations.

Motion carried.