Chemicals kill lake’s algae, and its fish

TACOMA — Hundreds of dead fish ranging from 20-inch-long carp to fingernail-sized perch floated in the waters of Wapato Lake on Saturday, a day after the lake was treated with chemicals to kill toxin-producing algae.

The fish were scattered around the shore of the ­pollution-­troubled lake where visitors gawked in disbelief.

“There are dead fish everywhere,” said resident Gilbert Durand. “The water looks clearer than I’ve ever seen it, but that only makes it easier to see all the dead fish.”

The 34-acre lake, usually ­yellow-green with algae blooms, looked blue-green from a distance. Up close, particularly near the shore, the water was as clear as a mountain lake.

The lake is managed by Metro Parks Tacoma. Agency spokeswoman Nancy Johnson said late Saturday that parks staff would “assess the situation and figure out what needs to be done.”

She noted that toxicity levels were already high due to the algae.

“We definitely had to take action of some sort because the algae itself, regardless of treatment, was resulting in previous fish deaths,” she said.

Earlier this month, Metro Parks agreed to pay TeeMark Corp. of Aitkin, Minn., $98,000 to treat the lake with 33,000 gallons of alum solution and 16,000 gallons of sodium aluminate. The chemicals bind with phosphorous, which drains into the lake from the surrounding area and fertilizes the algae.

The treatment posed no threat to people or wildlife, the company told The News Tribune three weeks ago.

Cheryl and Don Curtiss wondered aloud whether the algae-killing treatment was killing the lake’s fish.

“All the fish are dead or dying,” said Cheryl Curtiss. “What I’m concerned about now is what about the rest of the aquatic life.”

At the lake’s north end, frogs still perched on lily pads and woody debris. But instead of fleeing instantly when humans approached, the frogs lethargically hopped into the water only when a pebble was tossed their way, residents reported.

In recent years, the Curtisses said, the park has been plagued with problems ranging from polluted water in the lake to vandalism of the park fixtures.

Now, the fish kill.

The south Tacoma lake has been a persistent problem for years because urban runoff pollutes the water and encourages algae blooms.

The parks district has considered half a dozen different solutions to the pollution issues, ranging from an expensive overhaul of the lake to lesser measures such as the alum treatment.

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