The Halifax Regional Municipality is warning of a blue-green algae bloom at Penhorn Beach in Dartmouth. The city is warning people not to swim in the lake and to keep pets out as well. Lake users are urged to take the following precautions: Avoid water contact. If contact occurs, wash with tap water as soon as possible. Do not swim or wade (or allow your pets to swim or wade) in the water. Avoid consuming water from the lake. Avoid consuming fish from the lake.