DIAMOND LAKE AT A CROSS ROADS
Since 1910, Diamond Lake has been one of the most popular fishery destinations for Oregon anglers looking to catch big rainbow trout. Located just north of Crater Lake National Park, Diamond Lake is a natural lake with a total surface area of 3,000 acres, situated in the Cascade Mountain Range at an elevation of 5,182 feet. Fishless until 1910, the Oregon Fish and Wildlife Department began stocking rainbow trout into Diamond Lake where they began to flourish under ideal conditions. Soon anglers discovered the big fish in Diamond Lake.
By the 1940s, Diamond Lake became one of the most popular fisheries in the region, making a huge impact on the tourism economy of southern Oregon. Campgrounds and a popular resort were built to accommodate anglers and their families. Until recently, the impact on the local economy in this region of southern Oregon from this premier fishery was around $1.78 million annually.
Fishery Management Plan
In 1990 the Oregon Fish and Wildlife Commission adopted a management plan for Diamond Lake that set management objectives for this popular trout fishery. The goal was set for an average of 100,000 angler trips annually, with a harvest of 2.7 fish per angler trip and an average fish length of 12 inches.
Signs of a Problem
At some point during the early 1990s, someone illegally introduced a species of minnow, the tui chub (Gila bicolor), into the lake, most likely using the fish as live bait brought in from the Klamath Basin. Since its introduction, the population of tui chub has grown exponentially. Rainbow trout populations in Diamond Lake have substantially deteriorated over the past decade due to tui chub introduction. The population has declined in part because young fingerling rainbow trout (Oncorhychus mykiss) are unable to compete for food with the tui chub. The return of stocked rainbow trout fingerlings was about 70 percent in the 1960s, 1970s and 1980s. Today the return is less than 10 percent and decreasing. A team of scientists from ODFW, the US Forest Service and Oregon State University found that fingerling rainbow trout stocked in June 1996 and sampled in July were two inches shorter than expected and in poor physical condition compared to 1995 fish. The latest creel survey by ODFW provided estimates of 54,000 angler days and fewer than 57,000 fish caught, well below ODFW management objectives and angler expectations. While the population of rainbow trout has declined, the population of tui chub, a non-game fish, is now in the millions.
Tui chub negatively impact the entire food chain in and around the lake. Two pairs of bald eagles and six to twelve osprey pairs nest in the vicinity of Diamond Lake. These raptors rely on large rainbow trout as a primary food source. Populations of these birds are likely to decrease as populations of trout continue to dwindle. Tui chub also reduce the invertebrate food base of the lake, affecting the entire food chain of the lake. Amphibians, reptiles and populations of insectivorous birds are likely to be negatively impacted if the population of tui chub is not controlled.
No Easy Solutions
Since 1990, ODFW, the US Fish and Wildlife Service and the United States Forest Service have studied several options for removing the tui chub population from Diamond Lake. They recognize that long-term improvement of the fishery will require careful, scientific study and input from the public. These options include:
Fishery Options:
No Action: In the no action alternative, ODFW would continue to attempt to meet the goals and objectives of the Diamond Lake Management Plan. To achieve these goals ODFW would raise 600,000 rainbow trout at state hatchery facilities and release them into Diamond Lake to supplement the rainbow trout fishery. The fishery management plan and angler expectations would be difficult to attain through this option. The large population of non-native tui chub would be unaffected.
Partial Chemical Treatment of the Lake: This option involves using the chemical rotenone, an organic fish toxin, on the shoreline of Diamond Lake and physically removing as many tui chub as possible by seining, trapping and angling throughout the summer months. Partial chemical treatments at Diamond Lake in the early 1950s killed millions of chub without any improvement to the trout fishery. Extensive netting at Lava Lake in the Cascade Mountains has been ongoing since 1992 without significant decreases in tui chub populations. Fish management objectives for rainbow trout would not be attainable through this option.
Chemical Treatment with Rotenone: This option would eradicate the entire tui chub population in Diamond Lake over a two-day period in early fall. Diamond Lake would be drained to a level of between five and eight feet by pumping the water into Lake Creek. Treatment with Rotenone would eradicate all species of fish in the lake. This option would restore Diamond Lake to its status as a premier Oregon fishery. When rotenone was used in 1954 to eradicate the population of tui chub in Diamond Lake, the lake was restored to a prime fishery until re-introduction of tui chub occurred in the early 1990s. This option is favored by the ODFW. The cost to chemically treat Diamond Lake ranges from $3 - $4 million. If approved, this treatment option would likely occur in the fall of 2001. By spring of 2002, legal-sized and fingerling rainbow trout would be restocked in Diamond Lake.
Actions to Date
ODFW decided to seek a federal grant to fund the tui chub removal project from the Sport Fish Restoration Program, a federal program which helps state agencies improve recreational, sport fishing and boating opportunities. The program is administered through the US Fish and Wildlife Service. Federal funding requires the development of an Environmental Impact Statement (EIS) to study the various alternatives. The full Diamond Lake EIS scoping report is available on line at http://www.r1.fws.gov/diamondlake/final.htm
Because the project will use federal funds, it is also subject to the National Environmental Policy Act (NEPA). After the Final EIS is completed, the US Fish and Wildlife Service will make a final decision whether or not to fund the grant, allowing ODFW to carry through with the preferred course of action.
Public Process
Many comments on Diamond Lake issues have already been gathered. The response has been strong in favor of restoring the lake to a premier fishery location. Use of federal funds requires, and ODFW strongly encourages, continued public comment. The process used to gather information is intended to inform the public about the benefits and risks of each alternative, to examine alternatives and invite responses. The US Fish and Wildlife Service, the US Forest Service and the ODFW will develop a draft EIS available for public review. Public meetings about the draft EIS will be held in Roseburg and Medford. A completed draft summary of EIS findings will be made available on this web site.
Uploaded:
9/22/1999