Worries for wetlands

River levels in the Busselton shire have dropped to some of the lowest on record sparking concern about the health of the region’s wetlands.

The Department of Water’s Allan Pastega confirmed the Carbunup River was at its lowest on record last year and several others were also running dryer than usual.

The stream flow at the Carbunup River was 10,600 megalitres last year, less than a third of its average and lower than the previous minimum of 11,500ml recorded in 2006.

Mr Pastega said staff also recorded the second lowest on record at the Ludlow River, which was one of several which provided valuable run-off to the Vasse-Wonnerup wetlands.

He said the Vasse Wonnerup wetland relied on the Vasse, Ludlow, Sabina and Wonnerup river systems which fed into it.

The river had just 1129 megalitres of water, less than a tenth of its average.

“We know a 10 per cent drop in rainfall can cause a 30 per cent drop in run-off and because the catchments are so dry it’s like a sponge,” Mr Pastega said.

The Department of Water’s water resource manager Greg Davis said lower river levels would also impact vegetation which lived along the side of the rivers.

“Impacts of reduced flow are twofold, there’s an increased risk of algal blooms and less water for irrigation,” he said.

Mr Pastega said it was hoped early rains this year would prevent the rivers being subjected to another dry year.

“We’ve already had rain in January out of season so 2011 is on track,” he said.

CSIRO announced this week they would work with research organisations to assess the health of Australia’s river and wetland ecosystems.

The group said the findings from the eastern States study would be applicable to other river systems, including those in the Busselton shire.