Wagardu Lake, or Loch McNess as it was formerly known, in the Yanchep National Park is drying up and the long term affects on the native wildlife and birds appears to be unknown.
A walk around the lake shows stodgy mud pools.
It has been nearly three months since there’s been any rain. The lake is believed to be at least 70 percent below capacity.
Perth and Yanchep are heading for one of the driest summers for forty years.
On the Yanchep National Park website it states: “Due to current water levels, row boat hire on Loch McNess is unavailable.”
The wetlands at the Yanchep National Park have a significant importance to the region. The shrinking, muddy, oozy mess cannot support the normal abundance of wildlife that frequents the region.
The Sun City News understands that Yanchep National Park staff have been monitoring the dropping water level, but have not considered implementing any plans to save the lake.
The lake is part of a chain of lakes, caves and karst features that stretch from Herdmans Lake in Wembley all the way to Guilderton.
Caves in the Yanchep National Park have been drying up for many years, but this year the water level is the worst anyone has seen for over twenty years.
The Yanchep National Park is one of the state's oldest national parks with an extensive history, both indigenous and european.
During the mid-1930s the lake was dredged, substantially modifying and deepening the southern end, and creating man-made islands.
It is recorded in aboriginal history that Loch McNess is a mythological site with a Waugal inhabiting the lake and a spring or stream feeding the lake. It was known as Wagardu Spring.
These days the spring is no more than a dribble and evaporation off the lake is quicker than the water trickle can replenish.
Dredging the lake and replenishing the water levels is considered the only option available to save the lake.
In a documents titled ‘Dredge Wrecks in Loch McNess / Wagardu Lake it suggests: “Based on the historical information and current observations of lake depth and silt levels, combined with dropping water table levels, a dredging cycle is apparently required every 30 - 40 years to maintain the depth of the lake for ongoing recreational use.”
Two dredges would work in conjunction, the grab dredge removing reeds and rushes while the sucking dredge would pump mud and ooze from the lake.
The Department of Environment and Conservation told the Sun City News: “The option of dredging the lake bed is not being considered.
“The impacts of this approach on the wetland may prove to be far greater than the threat of seasonal drying of the lake.”
The DEC said: “Wildlife associated with the lake will continue to be monitored.”
“Waterbirds generally move seasonally and annually around various lakes across a wide area. They will use Loch McNess within their wider range.
“The only possible need for translocation for waterbirds would be during the fledgling stage if young birds are unable to move to alternative locations themselves.
“DEC has undertaken relocation of fledging waterbirds at Forrestdale Lake Nature Reserve over the past two years and would implement a similar strategy for Loch McNess if required.
“DEC is not aware of any resident waterbird species at Yanchep National Park that would need such assistance.
The DEC said a new management plan for Yanchep National Park was being developed and they anticipate that the document will be released for public comment this year.
The Department of Water who are responsible for monitoring and management of ground water, said: “Loch McNess is connected to a large body of groundwater which has experienced regional changes in levels and as a result water levels in Loch McNess have also fallen.”
The Department of Water is working with other agencies through the Gnangara Sustainability Strategy to address the broader, regional scale pressures on water levels, including reductions in the areas of pine plantations across the Gnangara mound and reductions in water abstraction from the mound.
The DEC added: “The significant reduction in annual rainfall over a number of years and its impact on ground water levels is visible across many of the wetlands of the Swan Coastal Plain including those located at Yanchep National Park.
“Perth is currently experiencing its longest period of consecutive days without rain in the past three decades and this is adding to the rate at which the water table is dropping.
“DEC and the Forest Products Commission have committed to the fast-tracked removal of pine forests located to the east of Yanchep National Park as a measure to help increase long-term ground water recharge.
The large wildfire in the summer of 2008-09 resulted in 2000ha of pine being removed from the groundwater catchment of the Yanchep caves. This is seen as critical to the maintenance of not only the wetlands within the vicinity of Yanchep National Park, but also to the endangered species that populate the groundwater within the cave systems.
“DEC and the Department of Water have invested in the establishment of alternative water resources to assist with the maintenance of ground water levels within the cave system.”
The final paragraph on the response to the Sun City News media enquiry stated: “While no departmental spokesperson may be quoted you can say this information was provided by the Department of Environment and Conservation.”
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