Fish in Lake Eildon and surrounding rivers that contain high levels of mercury
Mercury occurs naturally and in very low levels in rocks and soils. It may also occur in some soils and waterways from historical gold mining activities where it was used to recover gold from the mined, crushed rock.
The Upper Goulburn River (above Lake Eildon), Big River and Howqua River catchments have been associated with historical gold mining. Mercury has been found in river bed sediments and in some fish at these locations as a result.
As these rivers flow into the southern parts of Lake Eildon, it is likely that the bottom sediments and fish species contain mercury.
Testing of fish has shown that levels of mercury in long-lived fish species may be high. The most information is available for brown trout and redfin.
The following advice applies to recreational fishing in Lake Eildon (south) and the Upper Goulburn River.
Large brown trout (more than 40 cm fork length) caught in the following locations are likely to contain high levels of mercury:
- Lake Eildon – south-east lower region and the central region, up to Brier Cove and Point Robertson, including the arms of the Goulburn river
- Big river
- Howqua river.
Figure 1: Brown trout
Note: A fork length of a fish is as measured from the tip of the snout to the fork of the caudal (tail) fin.
Redfin are a predatory species that can live for a long time. Redfin caught in the following locations are likely to contain high levels of mercury:
- Lake Eildon – south-east lower region and central region, up to Brier Cove and Point Robertson, including the arms of the Goulburn river
- Big river
- Howqua river.
Figure 2: Redfin
These areas of high mercury levels are marked on Figures 3 and 4.
Figure 3: Map of Lake Eildon
Figure 4: Basemap – indicative map of the areas of Lake Eildon covered by this advisory
Amount of fish that can be safely eaten
Table 1 shows the amount of fish that can be safely eaten, according to the population.
Table 1: Amount of fish that can be safely eaten
Note that one serve equals:
- in adults, 150 grams (for example, two frozen crumbed fish fillets)
- in children under 6 years, 75 grams (for example, three fish fingers).
Water activities in Lake Eildon
Mercury is not very water soluble. It settles in the sediments of streams, rivers or the bottom of some parts of Lake Eildon. Testing of surface waters at various depths and locations in Lake Eildon found low levels of mercury, all within the acceptable level for recreational use, including swimming. This is also true for waters in the Upper Goulburn River.
Like all water activities, common sense safety rules apply to prevent drowning.
Drinking the water in the Upper Goulburn River (above Lake Eildon)
Untreated river water can contain a range of contaminants, including microorganisms that may cause illness. It is therefore not recommended that people drink untreated river water, regardless of its source.
For people living along rivers where a town drinking water supply is not available, rainwater collected from the roof is recognised as the most reliable and safest way to source drinking water.
Bush campers should carry in water for drinking. Alternatively, untreated river water needs to be boiled before drinking or using for cooking.
Tap water supplied by the local water authority
Goulburn Valley Water Corporation provides drinking water supplies for human consumption. Samples of this drinking water supply are regularly tested with all mercury levels well below the health-based Australian Drinking Water Guideline value.
Water samples from Molesworth and Woods Point (near Gaffney’s Creek) are also tested for mercury. These locations are called ‘regulated water supplies’, which means that they are available for a number of uses, but not for human consumption. Mercury levels in all of these samples were low.
See your local doctor if you or a member of your family have health concerns.
For general information about drinking water quality or the potential health effects of chemicals, contact the Environmental Health Program.
The Department of Environment Land Water and Planning and the Environment Protection Authority Victoria have contributed to the development of this advice.