The World Health Organisation has found the main water at the tailings facility at Gold Ridge Mine in Solomon Islands meets international standards.
The WHO carried out an assessment at the request of the Solomon Islands government after concerns about the health of communities near the site.
The December tests assessed whether discharging untreated water in a controlled way for a few months into the Tinahula River would be detrimental to the health of the people nearby.
The WHO says toxicological testing confirmed the untreated dam waters are not toxic to humans.
The WHO Representative to Solomon Islands Audrey Aumua says more than 3,000 people live in communities downstream from the dam and their health and safety is a priority.