Clumps of blue-green algae remain present in Apex Park lake and people have been warned not to paddle or drink water from it.
The algae has been in the lake, in Burnham-on-Sea’s Marine Drive, since July.
Sedgemoor District Council, which owns the lake, has put warning signs in place to prevent visitors and dogs from entering.
There is also a restriction on any permit holders for model boat use.
A council spokesman said: “We advise people not swim in the water and not to let dogs swim in the water or drink from it.
“People should not swallow the water and avoid contact with the algae.
“We remind people to please observe and abide by warning notices positioned around the water.
“The Environment Agency will also continue to monitor the situation and sample the water until it subsides.”
The algae can produce rashes after skin contact and illnesses if swallowed.
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