Contact with water in St Helen’s Loch should be avoided after samples taken by SEPA indicated the presence of blue-green algae.
As a precautionary measure, notices have been posted next to the loch in High Bonnybridge warning that contact with the water should be avoided.
Dog owners should ensure that their pets do not drink or swim in the water until further notice.
Adjoining landowners and fishing interests have been advised of the situation.
Falkirk Council are monitoring the situation with the assistance of SEPA and NHS Forth Valley.
St Helen’s Loch is not used as a public water supply.
Blue-green algae can be found in fresh waters across the UK.
Some algae can produce toxins which can cause health problems such as skin rashes, eye irritations and vomiting.