EPHRATA — With Grant County's Blue and Park lakes facing a possible rehabilitation this fall, which means state fishery officials would kill all the fish, both lake-side landowners and some fishermen voiced their opposition Thursday.

Under a state Department of Fish and Wildlife proposal, the cool, deep waters of these two lakes may be headed for a controversial treatment with rotenone.

About 40 people showed up to Ephrata High School for Thursday evening's public comment meeting hosted by the Department of Fish and Wildlife. Most who attended appeared to oppose the treatment, with eight people taking their turn to speak against it.

"I really like the idea of a natural, left-alone lake," said one landowner.

"Delay the rotenone treatment for one more year," said another. "Have patience and see if we have more than one bad year. Give these lakes another chance."

On opening day, this year, anglers averaged less than a fish per rod, the agency reported.

A few opponents of the treatment disagreed with the Department of Fish and Wildlife's statistics, saying trout fishing this year has been just as good as previous years.

"There's a lake up there that's not broke, so why do we need to fix it?" said one fisherman.

Others suggested environmental impacts of rotenone treatment are inconclusive. Some opposed thousands of dead fish washing up and accumulating on shorelines. With no removal of dead fish planned following the proposed rehabilitation, some near-lake residents are concerned with the odor.

Rotenone, which is extracted from ground-up roots of tropical plants in the bean family, kills fish quickly and then rapidly dissipates, according to fish biologists.

The chemical kills fish by interfering with their use of oxygen.

Scientific review of rotenone by the U.S. Environmental Protection Agency supported its continued use. It's become a favorite of fish experts because they are able to eradicate entire populations or communities of fish with minimum impact to non-target wildlife.

Blue and Park lakes, which are situated south of Banks Lake along Highway 17, have declining trout populations because of competition with illegally introduced and undesirable fish, said Jeff Korth, a state fish and wildlife biologist stationed in Ephrata.

The lakes have long been managed as trout lakes, requiring periodic rehabilitation. Rotenone has been applied eight times since the 1950s, most recently in 1996.

The problem, Korth said, is perch, bass, bluegill and sunfish have overrun the two lakes and are out-competing trout for food. By ridding the lakes of these fish, and stocking them with trout, proponents of the treatment hope the lakes remain among the state's top attractions for trout angling.

Many who oppose the proposed rehabilitation, Korth said, simply prefer catching spiny-rayed fish, which have been abundant.

"We can't produce everything for everybody in the same lake," he said Thursday. He said other lakes in the area are maintained as warm-water fisheries, with plenty of perch and bass.

Managing Blue and Park lakes as warm-water fisheries wouldn't create the same amount of recreation, Korth said, which is evidenced by declining participation as trout fishing slows.

Some rehabilitation opponents recommend removing catch limits on non-trout species. Others suggested starting fishing tournaments, which could target those species considered undesirable by fishery managers.

Only rotenone rehabilitation or stocking of catchable-sized fish can restore the trout fishery, Korth said.

If rehabilitation occurs every 10 years the state would likely spend about $440,000. That money would pay for the rehabilitation itself, a one-time planting of catchable-sized trout, followed by nine years of planting fingerling trout, according to the department of fish and wildlife.

In comparison, the department estimated the state would spend about $1.5 million planting catchable-sized trout for the same 10-year-period.

Without significant capital investment, however, current resources aren't available to provide catchable-sized trout on a regular basis without severely impacting hatchery production for many other fisheries, Korth said.

The lakes' rehabilitation plan is scheduled to be finalized late next month, and treatments would begin in October.