Page 734 - Week 03 - Tuesday, 28 March 2023

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The 2022 report does tell a positive story for our waterways. The La Nina conditions persisted for a third consecutive year, with increased run-off and high energy flows in our waterways. The high flows had a flushing effect on our rivers, improving dissolved oxygen levels and diluting salts and minerals. This produced overall positive results for water quality.

This year we had the highest number ever of “excellent” and “good” ratings recorded in the nine years that the CHIP report has been produced in its current format. It breaks the previous record set in 2021.

Specifically, on Lake Tuggeranong, in which I know a number of members have an interest, results for sites in the Lake Tuggeranong catchment showed a general trend of improvement on the previous year. We know there are some complex issues with Lake Tuggeranong, and it is heartening to see this improvement in the health of the lake, which is such an important hub for the community.

Lake Tuggeranong itself improved from “poor” in the previous year to “fair” in 2022, a welcome outcome for waterway health and for the many local residents who enjoy the surrounds of Lake Tuggeranong. Isabella Pond, the main settlement pond for waters entering Lake Tuggeranong, and the Lake Tuggeranong wetlands both remained stable, in a fair condition. In the broader catchment, over half of the sites in the southern ACT catchment showed increased dissolved oxygen levels, which is an indication of improved health.

There is a lot more detail in the report, but I am pleased to see that there are positive signs there. We do still have a lot of work to do in the Tuggeranong catchment.

MR DAVIS: Minister, could you provide an update specifically on work that the government has done and investments that the government has made to improve water quality in Lake Tuggeranong and the surrounding catchment?

MR RATTENBURY: As members may recall, we have done quite a lot of work through the ACT Healthy Waterways program to improve the quality of water entering our lakes and waterways and flowing downstream into the Murrumbidgee River system. Under stage 1 of the Healthy Waterways program, the government built seven water quality infrastructure assets in the Lake Tuggeranong catchment, as part of the $93.5 million co-investment with the Australian government. These assets included rain gardens, a wetland and waterway restoration project. These are contributing to a significant reduction in nitrogen, phosphorus and suspended sediments entering Lake Tuggeranong via urban stormwater.

As per the CHIP report, phosphorus concentrations have decreased across the Lake Tuggeranong catchment, even though we did, unfortunately, continue to see algal blooms in both Lake Tuggeranong and at Point Hut. Nitrates were still detected at high levels in the Lake Tuggeranong catchment. These are an ongoing issue because of the highly urbanised catchment.

The government is now working on implementing stage 2 of the Healthy Waterways program, which will see the construction of up to 10 new water quality assets in the Lake Tuggeranong catchment. These include a set of bioretention swales to replace

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