Recreational fishers and boat users are concerned for the future of Lake Lonsdale due to low water levels and a blue-green algae warning.
Situated 16.5 kilometres from Stawell, the lake is at 8,470 gigalitres or 18 per cent, only two percent higher than this time last year.
Between December 2015 and July 2016, the lake didn't have enough water to record.
Lake Lonsdale Action Group president Ray Howard said the district had not had enough rain to make an impact on the water levels.
"There is a large run-off area and the lake fills up quite quickly compared to other lakes in the area," he said.
"But we just haven't had the rainfall needed to make an impact of the water levels."
Mr Howard said the low water levels and now the algae warning put pressure on other waterways in the region for fishing and recreational use.
"An example of this is Lake Fyans which can become crowded at busy times," he said.
"It can create dangerous situations between recreational boat users, fisherman and swimmers if it's too overcrowded."
Mr Horward said he was concerned with the lack of fish and yabbies in Lake Lonsdale.
"One of the biggest attractions to Lonsdale is the yabbies and the fishing and either of them hasn't done any good since the last time it was dry," he said.
"We've been in touch with Wimmera Catchment Authority who do an annual survey of the upper reaches of Mount William and we've requested a survey to be done on the lake to find out what's wrong with it.
"The fish have not gone and the yabbies have not gone so there's something very drastically wrong with the lake and we need to find out what it is."
Wimmera Catchment Management Authority chief executive David Brennan said blue-green algae events weren't uncommon in waterways throughout the Wimmera and Victoria.
"Over summer when there is warm weather conditions that are conducive to algae bloom outbreaks," he said.
"While it's unfortunate it's something that happens on a regular basis to waterways.
"Since 2016-17 we've been surprised the fishing and yabby numbers haven't been at the historical levels the lake has had in the past.
"We're really inquisitive to understand why the lake isn't firing from the yabby and fishing perspectives."
Mr Brennan said the organisation would be conducting surveys and would consult with the action group to investigate the matter future.
"We want to know if this is circumstantial or if it's something a bit more serious that we need to consider," he said.
"We have a very keen interest in the overall health of the waterways and certainly working closely with the community to promote the environment."
Recreational boat user Terry Monaghan has skied on the lake for more than 50 years.
"Lake Lonsdale is the larger lake and can cope with more traffic than other lakes within the region," he said.
"As a skier, Lonsdale is a far superior lake because there is protection from the southerly winds and a lot more options on Lonsdale with longer, clearer runs.
"People come to the region for the lake and especially from Horsham and Ararat, distances not too far away.
"But when the yabbies are on I've seen people come from New South Wales and South Australia to hunt the yabbies at Lonsdale.
"The lake isn't just for fishing or recreational use. It's a healthy, vibrant and diverse environment for nature."
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