Diamond Lake to be Drained and Poisoned

Diamond Lake at sunset.

After years of controversy, a decision has been reached that will drain the lake by 8 feet, treat it with the poison rotenone, leave wetlands parched for up to a year. This is part of an effort to expel the invasive fish species tui chub and restore the dominance of the rainbow trout, a species treasured for its commercial value.




Diamond Lake is naturally a fishless lake. The Oregon Department of Fish and Wildlife (ODFW) introduced fish in 1910, which began the economic returns from the lake. But Rainbow trout fisheries began to decline in the 1940's when another introduced fish, the tui chub, multiplied. Tui chub originate from Klamath Lake and have invaded or are naturally present in virtually every lake in the area. In 1954, Diamond Lake was poisoned with rotenone, killing every living thing in the lake. Because there were few pre-surveys and post-monitoring, it is unknown how devastating this treatment was to the rest of the ecosystem, though the Forest Service now believes that some plant communities, like Lesser bladderwort in the South Shore wetlands, were degraded when the wetlands were drained to draw down the lake in preparation for rotenone.

But the re-introduced rainbow trout did well. For some years afterwards, Diamond Lake enjoyed a boom in recreation dollars and fishing permits, even exceeding 100,000 anglers per year. Unofrtunately, the tui chub came back in 1992 and again made the rainbow trout more difficult to catch. Now ODFW is going to poison the lake again...

The failure of the past rotenone treatment should be a sign that something different needs to be done this time. It will be virtually impossible to keep tui chub out of the lake in the future because they are used as bait, or carried into the lake on boats or wildlife. No other lake is proposed for poisoning, only Diamond Lake. ODFW's economic goals for the lake are unrealistic. It forces the stocking of Rainbow trout and a goal of 100,000 anglers per year. The only apparent way to sustain this level of fishing is to re-poison the lake every few decades to keep it free of any competing species.

The Proposals:

The ODFW proposed action, Alternative 2, had the same goals with virtually the same management: rotenone the lake and restock it with a lot of rainbow trout (and some other species) with the highest possible profits from 100,000 angler days per year. Alternative 3 was a little better, and was the Forest Service's "preferred alternative." It proposed to rotenone the lake, but have a different stocking strategy. Instead of stocking with rainbow trout fry, they will stock with adult fish. Because mature rainbow trout feed differently, it will help maintain a higher water quality.

We favored Alternative 4, which would have removed 95% of the tui chub for 6 years, and attempted to keep the remainder of the tui chub in check with predacious fish, like salmon. This would have provided for the continuation of plenty of fishing and swimming.

Both Alternative 2 and 3 would have treated Diamond Lake and Lake Creek in a harsh and drastic way unnecessary with Alternative 4. To apply rotenone, Diamond Lake needs to be drained halfway. A canal will be dug so the lake can be drained into Lake Creek (which flows from Diamond Lake into Lemolo Lake). In October of this year they began to drain the lake. It will stay half full all through the summer of 2006. In October of 2006 they will put about 238,000 pounds of rotenone into the lake. They will also drip 375 gallons of liquid rotenone into Short Creek and Lake Creek (inlet and outlet to the lake) for 17 days. Because it is illegal to put pesticides directly into a creek, the Forest Service must temporarily relax their rules. After a couple of months, they will start to fill the lake again, and will immediately restock it with fish the next spring.

The alternative ultimately chosen was Alternative 5, nearly identical to Alternative 2. It differed in that liquid rotenone, not powdered, would be used "in the shallow, weedy areas of Diamond Lake."

The impacts:

The rotenone treatment is expected to briefly contaminate about 80 drinking wells of summer homes around the lake. Though drinking water will be provided to the residents, they must wash with the contaminated water.

For the bald eagles, osprey, and other fish eating birds, the Forest Service will have an 18-month supplemental feeding program. Rotenone-contaminated water and dead fish are not expected to kill any wildlife that drink and eat it.

When the lake is drained, it will dry up the surrounding wetlands. When the lake is filled, it will dry up Lake Creek. The cumulative effects of this treatment could mean the end of a Lesser bladderwort (pictured at left) population along the south shore because it is currently "only barely holding on." Other rare flora includes the California elfin saddle (pictured at right), Goblin's Gold, and Water Bulrush. Of the 30 plants in these sites, the Forest Service will try to save 10 by hand watering.The drying of the South Shore Wetlands and Lake Creek will negatively impact wildlife that depend on the water, such as bats, the rare Crater Lake tightcoil snail, pacific fisher, bufflehead, and numerous other waterfowl and shorebirds. The dewatering of the south shore wetlands could result in permanent changes to the wetland environment, potentially changing the rare plant communities that are adapted to them. In addition to fish, amphibians and reptiles (including turtles) are expected to be killed by the Rotenone.

Are we going to do this every 40 or 50 years? Poor Diamond Lake. It deserves a better, less greedy management plan.