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2006 Diamond Lake Restoration Treatment

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ODFW sucessfully treats Diamond Lake with rotenone

In September 2006, the Oregon Department of Fish and Wildlife successfully treated Diamond Lake with rotenone, a safe and effective pesticide derived from plant roots, to rid the lake of an estimated 90 million tui chub. The treatment goal is to restore the lake's water quality and recreational trout fishery.

The successful treatment was the culmination of years of effort and collaboration between ODFW, the Umpqua National Forest, Oregon Department of Environmental Quality and other agencies in the Diamond Lake Working Group. State Representative Susan Morgan kicked off this effort in 2002.

The treatment project cost close to $6 million in federal, state, county and private contributions. The Oregon Wildlife Heritage Foundation and many private donors helped with fund-raising efforts.

Diamond Lake first was treated with rotenone in 1954 when tui chub, a minnow native to the Klamath Basin decimated the recreational rainbow trout fishery. That treatment rid the lake of chub and resulted in decades of high quality trout fishing until the minnows again were discovered in the lake in 1992. ODFW officials believe tui chub were illegally used as live bait.

Since their discovery in 1992, the tui chub population climbed rapidly to an estimated 8 million adults and 90 million juveniles. The rainbow trout fishery collapsed and water quality deteriorated, resulting in toxic algae blooms that closed the lake to water contact for portions of the summers of 2001, 2002 and 2003.

Now that the lake is free of tui chub, water quality, zooplankton, and benthic (insect) populations already are on the rebound.

Anglers can once again fish Diamond Lake beginning in spring 2007 when ODFW stocks it with 50,000 – 100,000 fingerlings and 10,000 – 25,000 catchable-sized trout. A minimum of 50,000 put-and-take rainbow trout will be stocked pending funding.

Some of the larger-sized trout will be a predacious variety to help minimize the danger posed by any tui chub or other small fish that may be illegally introduced into the lake. The numbers of fingerling trout released will gradually increase over the next few years, in concert with the recovery of the lake's health.

Diamond Lake will be closely monitored for years to come by ODFW, the Umpqua National Forest, and Oregon Department of Environmental Quality.

These agencies will monitor water quality in both Diamond and Lemolo lakes and the North Umpqua River, and check fish species composition in Diamond Lake. Population levels of phytoplankton, zooplankton, benthic invertebrates, flora and fauna in and around Diamond Lake also will be monitored.

The future of Diamond Lake is in the hands of everyone who enjoys it. Keeping tui chub – and other invasive species such as zebra mussels and noxious weeds – out of Diamond Lake is critical to its future.
You can help by NOT transporting or using live fish for bait. It IS the law and it is NOT good for the environment or the fishery. Boaters can help by emptying their bilge water and checking their boats for invasive species before they launch into the lake.

ODFW thanks the Umpqua National Forest, Oregon Department of Environmental Quality, Diamond Lake Working Group and the many public and private partners and employees who made the restoration project successful.

A new legacy of trout fishing and clean, productive waters at Diamond Lake is right around the corner. Please help us keep Diamond Lake a true Gem of the Cascades.


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