Raw sewage was discharged into Lake Burley Griffin and the National Capital Authority has closed Yarralumla Bay to all recreational users.

ACT Health Directorate is advising it is unsafe to use Yarralumla Bay for any activities that involve contact with the water such as swimming, canoeing, recreational boating, rowing or fishing.

The authority posted warning signs around the exclusion area and will monitor the water quality, and will only reopen the area when two sets of water quality results indicate bacteria levels are safe.