SAN FRANCISCO (KGO) --Our warm weather has prompted an algae warning at San Francisco's Mountain Lake.
A type of blue-green algae is blooming on the natural lake on the southern border of the Presidio.
The Presidio Trust says the algae could be bad for your health or that of your pet.
So, it's banning access to Mountain Lake Beach until the algae bloom subsides.
It could last several months.