ROSEBURG – Diamond Lake now has non-detectable levels of rotenone present, the Oregon Department of Fish and Wildlife announced this week. The chemical compound, used in September to rid the lake of tui chub and improve its water quality, has broken down to trace levels.

According to Dave Loomis, ODFW’s incident commander for the Diamond Lake Restoration Project, water samples taken Oct. 16 showed rotenone levels below two parts per billion, the amount necessary to deem any remaining rotenone has no biological relevance to the lake or water flowing downstream. Water samples have been shipped weekly to a California lab for rotenone level testing.

”It’s ironic that the 1992 Halloween trick turned into a trout angler’s treat for Halloween 2006,” Loomis said. ”We discovered tui chub in the lake Oct. 31, 1992, and it’s now on its way to a full recovery.”

The Umpqua National Forest continues to collect water quality data and may open the gates on the old canal in mid-November to allow 10 cubic feet per second (cfs) of water to flow through a specially designed pipe and into Lake Creek. Once the lake’s water level rises a few more feet, water also will flow into Lake Creek through the ODFW weir restored last year.

Diamond Lake will refill naturally through rain and snow-pack and should be at its normal level by late spring 2007 when ODFW will stock it with fingerling and catchable-sized rainbow trout.

The September rotenone treatment was the culmination of several years of cooperation between state and federal agencies and Douglas County, and the signing of the project’s Final Environmental Impact Statement in Dec. 2004.

The Umpqua National Forest, ODFW, Oregon Department of Environmental Quality and other agencies and individuals will continue to monitor Diamond Lake’s water quality, fishery, presence of invasive species and flora and fauna recovery around the lake.