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Algae prompts swimming closure at Diamond Lake

The U.S. Forest Service closed Diamond Lake to swimming and wading today, and may close all access to the lake for the Fourth of July, because of a toxic algae bloom in the water.

This is the third straight summer Diamond Lake has been closed temporarily because of massive blooms of the blue-green Anabaena flos-aquae algae, triggered by the lake's tui chub infestation.

The algae can produce toxins that can make humans sick, but no human deaths have been attributed to it.

Pets, especially dogs, are also susceptible, and the toxins can be lethal to animals.

— Beginning today, the Umpqua National Forest has banned water-skiing, swimming and wading at the lake. Boating and fishing will remain open until Thursday, when tests on water samples taken Monday will determine if toxin levels are unhealthy for all contact, Umpqua Forest public affairs officer Cheryl Walters said Monday.

We really don't want to close the lake to boating for the Fourth of July, Walters said. But if we have to for safety reasons, we will.

Similar closures occurred last July and in August 2001. In each case, the closures lasted 10-14 days before the algae died and decomposed.

We think it's tied to the early hot weather, and the huge population of tui chubs here really has this lake out of balance, Walters said.

This year's early showing of the toxic algae could be tied to an increase in populations of the tiny fish.

Dave Loomis, an Oregon Department of Fish and Wildlife biologist, said recent sampling shows the lake likely has more tui chubs this year than last. Last year's population was estimated at 30 million. The small, non-native fish likely were introduced illegally by an angler as bait in the early 1990s, and the chubs have since overrun the lake.

The Forest Service is preparing to launch an environmental impact statement on the possibility of chemically treating the lake to kill the chubs.

Facilities around the lake will remain open, and drinking water sources at campgrounds, RV parks and resorts are safe and not threatened, Walters said.

The Diamond Lake Resort will remain open and an above-ground pool will be available for swimmers. The resort also plans its annual fireworks display over the lake Friday night.

Umpqua Forest employees will distribute fliers to campers and other visitors to direct them to alternative areas for swimming and water-skiing during the closure, Walters said. Most will be pointed toward Lemolo Lake, a reservoir about 15 minutes away by car, she said.

Reach reporter Mark Freeman at 776-4470, or e-mail