It’s official – two weeks have gone by, and nary a sign of toxic algae remains in Lake Tapps.
Over the Aug. 12 weekend, the Tacoma-Pierce County Health Department received a dozen reports of swimmers becoming ill after their lake activities.
Two more cases were reported on Aug. 16 and 17.
The symptoms of each case resembled exposure to toxins produced by cyanobacteria, or toxic blue-green algae.
Lake Tapps never closed, but the health department at first cautioned everyone from swimming in the lake until tests could verify whether toxins were leaking into the water.
On Aug. 22, the health department confirmed the toxic algae remained in the lake, but it wasn’t producing toxins, and the swimming caution was downgraded to an advisory, warning people about the dangers of swimming in the algae.
“The message we have for the public is simple: if you see algae in the water, (then) people and their pets should stay out,” said Brad Harp, the department’s water program resources manager, in a press release.
The health department continued to monitor the water. On Aug. 29, samples were taken from the two public swimming beaches on the lake — results showed low levels of algae, and less-than-detectable levels of toxin.
More tests on 15 areas of the lake on Sept. 1 showed no more algae in the lake.
These results were repeated a third time after 16 additional areas of the lake were tested on Sept. 6, satisfying the health department’s requirements for lifting the advisory.
“This is consistent with our standard protocol to keep the advisory in effect until no algae is present for two consecutive weeks,” health department Community Relations Manager Edie Jeffers wrote in an email update.
Drawdown and fill-up
The lake is free of toxins, but with Labor Day come and gone, Cascade Water Alliance announced the lake’s drawdown and fill-up schedule for fall and spring.
Starting Sept. 6, Cascade stopped all water from the White River from filling the lake. The company expects the lake to be down about a foot around Thanksgiving, at which time homeowners on the lake should consider taking their boats out of the water before water levels get too low.
Cascade will be finishing their work on the energy dissipating valve at the powerhouse through December, and when the project is complete in January, draw down the lake manually by 6 to 8 feet.
At this point, homeowners can start projects or make improvements to their docks, given they have the proper permits for construction.
The lake is planned to start being filled in mid-February to early March, and reach full recreation levels (541.5 to 542.5 feet) by mid-April.
Cascade plans to bring the lake up to its full height of 543 feet for a short time in the spring.