The Ministry of Environment says they won't know what level of blue green algae is present in Lake Rosalind until further testing results are available next week.
In the meantime, the "Do Not Use Water Advisory" remains in effect for Lake Rosalind and Marl Lake.
Heather Pollard, district supervisor for the Owen Sound Office of the Ministry Of Environment, says initial results from tests conducted Monday show the toxin is still present in the water.
Residents should not use the water for drinking or bathing.
A residents group had an accredited lab conduct private tests earlier this month that showed the algae levels were within safe limits.
However, the heath unit will not lift the advisory until further test results from the Ministry of Environment indicate it is safe to do so.
Early next week, the ministry hopes to release test results pinpointing levels of the Blue Green Algae in the Lakes.