STAGNANT water and shoulder-high weeds are turning Glenmore Park's Blue Hills lakeside into a swamp, resident Ben Mackie said.
The Star reported on similar problems at Blue Hills in 2010.
Mr Mackie said that although Penrith Council had since removed most of the weeds and restored the waterfall, the problem had returned.
"The wharf has become infested, the waterfall has been turned off and the water is stagnant; it stinks," he said. "We expected this to be maintained."
He also said the weeds were becoming home to rats and snakes and even providing cover for young people intent on mischief, such as throwing eggs at homes.
"It's devaluing our properties," Mr Mackie said.
In 2002, Mr Mackie built his home near the lakeside, which included a waterfall, because he found it attractive.
"The water used to flow over the rocks and families used to walk around there," he said.
"I challenge anyone to walk around there now."
He said that when he bought his property, the developer assured him the circulation system would keep the lake clean and the waterfall running.
But he said things changed when Penrith Council took over the estate's maintenance in 2006.
A spokesman for Penrith Council said council officers were organising a clean-up of the lakeside drive.
"The work, [which] should be completed in the next few weeks, will include removing weeds and rubbish and cleaning the banks," he said.
"A regular clean will then be implemented."
He also said contractors would look at repairing the waterfall pump.
Mr Mackie said Penrith Council had to decide if it wanted to preserve the artificial wetlands.