PORT TOWNSEND — Gibbs Lake is now off-limits for swimming.
Warning signs went up Friday at the popular swimming hole south of Port Townsend after results of a water sample test discovered that the level of microcystin, a toxin created by blue-green algae, had risen above the safety threshold.
“People should not swim in the lake now,” said Greg Thomason, Jefferson County environmental health specialist, on Friday just before he left his office to erect the new signs.
“Stay out of the water.”
The level of microcystin jumped to 7.9 micrograms per liter of water last week after having been measured at only a trace the week earlier, Thomason said.
The safety threshold is 6 micrograms per liter of water.
The most severe effect of microcystin is long-term. Some people who have consumed water containing the toxin over a long period of time have developed liver failure.
But the toxin has short-term effects, too, Thomason warned.
Those effects can include nausea, vomiting, diarrhea, skin irritation and burning, abdominal pain, blistering in the mouth and sore throat, he said.
Microcystin can enter the body through the skin — and through the lungs, “even breathing the mist from the shore,” Thomason said.
Gibbs Lake is not closed. Although the warning sign counsels no swimming, it says boating and fishing can be done if boaters avoid areas of scum and if fish are well-cleaned and guts discarded.
Warning signs also say that “algae toxins may be present in fish tissue” and direct people to phone the Jefferson County Health Department at 360-385-9444 for more information.”
No anatoxin-a — another blue-green algae-produced toxin commonly seen in East Jefferson County lakes — was found in Gibbs Lake.
High levels of anatoxin-a, a quick-acting nerve toxin, have kept Anderson Lake closed since May 3.
Lake Leland north of Quilcene — the other lake tested last week — remains safe, Thomason said.
Caution signs remain there and at Crocker Lake, which is near the U.S. Highway 101-state Highway 104 intersection, only because both contain algae known to sometimes produce toxins.
Weekly tests are announced Fridays after samples are taken Mondays.
No toxic blue-green algae has been reported in Clallam County, where health officers do not test for toxins; instead, they visually monitor lakes for signs of algae bloom.
Report algae blooms in Clallam County by phoning 360-417-2258.
Report algae blooms in Jefferson County by phoning 360-385-9444.
For more information about lake quality in Jefferson County, visit the environmental health website at http://tinyurl.com/6z64ofy.
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Managing Editor/News Leah Leach can be reached at 360-417-3531 or at leah.leach@peninsuladailynews.com.
