Blue Lake is in Kosciuszko National Park and is one of only 4 cirque lakes on mainland Australia. A cirque lake is one in a valley that is shaped like an amphitheatre and formed by glacial erosion.
Blue Lake has a unique dimictic thermal regime, which means it undergoes 2 seasonal mixing cycles a year. Layers of cold and warm water reach the same temperature in spring and autumn and can mix throughout the lake. This helps regulate the temperature of water flowing from the lake.
The Ramsar site also includes Hedley Tarn, a smaller lake about 400 metres downstream in the outflow creek from Blue Lake.
Blue Lake became a Ramsar site in 1996.
Why these wetlands were listed as a Ramsar site
Countries that sign up to the Ramsar Convention can nominate sites to be listed as Wetlands of International Importance (Ramsar sites). The site must meet at least one of 9 internationally accepted criteria.
The wetlands around Blue Lake and Hedley Tarn were listed under the Ramsar Convention in 1996 because they meet the following criteria.
Criterion 1: Representative or unique wetlands
The site is a rare example of near-natural alpine wetlands, because it has been protected within Kosciuszko National Park for more than 50 years. Blue Lake and Hedley Tarn are surrounded by alpine herb fields, heaths, fens and bogs.
Criterion 2: Threatened species or ecological communities
The Blue Lake Ramsar site supports various threatened species, including:
The site also supports plants and animals important for maintaining the biological diversity of the south east coast drainage division.
The site supports plant species limited to alpine areas, including:
- snow buttercup
- rock or branched caraway
- snowpatch cushion-plant
- Kosciuszko pineapple-grass.
How the site is managed
Management of this Ramsar site is guided by the following:
- the site’s Ramsar information sheet
- its ecological character description
- the plan of management for Kosciuszko National Park.
Threats to the Ramsar site
While Blue Lake and Hedley Tarn are considered to be in a near-natural condition, the main threats to this site’s ecological character include:
- climate change
- cloud seeding (a form of weather modification that increases rainfall)
- recreation and tourism
- bushfires
- erosion and sedimentation.