Water abundance key
The availability of water for environmental releases looms as a major ally in an effort to stem outbreaks of toxic blue-green algae in Wimmera-Mallee waterways.
Catchment experts said this week that flowing water had the potential to negate some of the conditions that promoted algal proliferation.
But they also conceded that there were no guarantees and waterway ‘end points’ where water pooled and became still would be particularly vulnerable with the onset of more light and heat during summer.
Wimmera Catchment Management Authority monitoring officer Mark Toomey made the comments in response to questions about a blue-green algae outbreak at Natimuk Lake.
“The issue is that the overland flows we experienced during the floods have captured an excess of nutrients that have built up in the landscape over time,” he said.
“When sediments containing these nutrients are flushed into waterways it provides enhanced conditions for aquatic and plant growth. This is most likely to occur in summer when there is more warmth and sunlight to promote growth.”
Mr Toomey said this year’s winter and spring had been considerably dryer than last year.
“We’ve had less inflow from rain into the Wimmera River system but we’ve maintained a continuous flow and this can alleviate some of the issues involving algal growth. Of course algae can still occur in flowing water but circumstances aren’t as ideal as still conditions.”
Mr Toomey agreed that Lake Hindmarsh, the major ‘end point’ of the Wimmera River, was among lakes at risk of having algal blooms this summer.
“It’s a large, shallow warm-water lake where light can easily penetrate through the water column. So yes it does have the potential to promote algae,” he said.
Mr Toomey said outbreaks of blue-green algal underlined the importance of CMA rehabilitation work on river-front areas to establish ‘buffer’ zones to help filter sediment build-up.
Figures earlier this week showed Wimmera-Mallee reservoirs were 67 percent full.
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Posted on Dec 8 2011