Nutrient Levels

The current integrated status for nutrient levels in Port Phillip Bay is Fair and the trend is Declining. This status is informed by available time-series data. The confidence score for this data is Medium.

The integrated status for nutrient levels is based on the average of indicator scores achieved for total nitrogen, total phosphorus, dissolved inorganic nitrogen and dissolved inorganic phosphorus.

In 2022-2023, assessment data was available for the 4 sub-segments providing an overall score for Category I: All nutrients, of Fair.

The current status of dissolved inorganic nitrogen in Port Phillip Bay is Fair and the trend is Stable. This status is informed by the available time-series data. The confidence score for this data is Medium.

The overall status for 2022-2023 in Port Phillip Bay has been assessed as Fair, and has been declining in recent years maintaining a Fair status since 2019-2020.

Time-series information for dissolved inorganic nitrogen levels is available from 1984 with regular sampling at 3 sites (Hobsons Bay, Corio Bay and Central Bay), with an increase in the number of sites monitored beyond 1990. Additionally, there are discrepancies in the confidence of analysis where annual sampling numbers have not been met.

Currently 6 sites are actively monitored by Environmental Protection Authority Victoria (EPA) these include; Hobsons Bay, Corio Bay, Central Bay, Long Reef and Dromana and Patterson River.

The current status of dissolved inorganic phosphorus in Port Phillip Bay is Fair and the trend is Stable. This status is informed by the available time-series data. The confidence score for this data is Medium.

The overall status for 2022-2023 in Port Phillip Bay has been assessed as Fair, maintaining an overall status of Fair since 2018-19, with a Poor status observed in the Exchange segment.

Regular monitoring occurs at 6 sites beyond 1989-1990. Previously, Geelong Arm and the Exchange have consistently had the lowest status scores ranging between Poor to Fair, with Hobsons Bay showing a Good to Fair status throughout the data available.

The current status of total nitrogen in Port Phillip Bay is Poor the trend is Declining. This status is informed by the available time-series data. The confidence score for this data is Medium.

The current status of total phosphorus in Port Phillip Bay is Good the trend is Stable. This status is informed by the available time-series data. The confidence score for this data is Medium.