All downstream communities along the Kwara, Tinahula and Matepono rivers in Central Guadalcanal are advised to stop using the rivers until advised by Ministry of Health and Medical Service and the World Health Organisation that it is safe.
A statement from the Ministry of Health says information received suggested, after the recent heavy rain, the Gold Ridge tailings dam has overflowed the spillway.
It says this may carry with it sediments containing high levels of arsenic.
The Health authorities advised the communities not to use river water for drinking, cooking, washing, bathing or fishing until further notice.
Meanwhile, the statement says downstream communities are advised NOT to eat food, including fish, from the river, NOT to prepare food or wash cooking utensils with river water and NOT to eat animals that have died in or near the river.
It says if the dam wall breaks, there may be a risk of drowning or injury due to the increased water flow.
It adds communities should be prepared to evacuate quickly to higher ground if required.
The Health authority says it is committed to the health and safety of communities living nearby and downstream of the Gold Ridge tailings dam and will provide updated information as it becomes available.