The Tacoma-Pierce County Health Department issued toxic algae cautions Thursday for Spanaway Lake and three other bodies of water.
The advisories warn people not to swim, wade or fish in areas with algae. They also say to keep children and pets away from the algae.
Besides Spanaway Lake, algae advisories were issued for Ohop Lake near Eatonville and Twin Lakes and Whitman Lake, both in the Kapowsin area.
Algae blooms look like pea soup or like green, blue or brown paint on lake surfaces.
“We just ask people to avoid areas where there’s visible algae,” said Ray Hanowell, with the Tacoma-Pierce County Health Department.
“I think this stretch of hot weather has triggered a lot of algae growth,” he said.
In Kitsap County, health officials were dealing with a more serious threat in a recreational lake: norovirus.
Kitsap County officials said Thursday that norovirus is responsible for sickening more than 260 people at Horseshoe Lake County Park in the Port Orchard area last weekend.
Tests of stool samples confirmed the presence of the contagious virus that causes stomach pain, nausea, diarrhea and vomiting.
Officials expect test results Friday of water samples sent to the federal Centers for Disease Control to show whether the virus is still present in the park’s swimming area. They expect to make a decision whether to reopen the park after getting those results.
Hanowell said he doesn’t expect the norovirus outbreak at Horseshoe Lake to spread to a Pierce County lake.
“Outbreaks like this are pretty isolated events,” said Hanowell, an environmental health specialist.
For the local algae blooms, the health department will check the affected lakes every week and decide if the advisories should continue.
Toxic algae cautions are fairly common. If conditions warrant, the health department can issue a more serious warning advisory or close a lake to public access.
Swallowing lake water containing algae or prolonged skin contact with algae can result in muscle weakness, vomiting, diarrhea or nausea.
For more information on toxic algae, visit tpchd.org/toxicalgae.
The Associated Press contributed to this report.