DAVIDSON COUNTY, N.C. -- Health officials are urging people to be cautious before heading to High Rock Lake after seeing potentially toxic algae blooms.

The North Carolina Department of Health says a sample of algae from the lake tested positive for the bacteria known as "black mat algae".

Experts say it grows in fresh water and then floats to the surface in large mats.

It can be toxic, so don't touch it and keep children and pets away.