BOISE The U.S. Bureau of Land Management has approved a plan proposed by NERCO Minerals Inc. to prevent cyanide poisoning of wildlife drinking from tailing ponds at the company's DeLamar Silver Mine.

NERCO submitted the plan as required by a BLM notice in November after 23 ducks and other waterfowl were found dead or dying at the DeLamar Mine's tailing ponds, near the Oregon border about 10 miles west of Silver City in Owyhee County.

The plan calls for NERCO to test the feasibility of cleaning up the pond by using a new technology developed by DuPont Co. to recover the cyanide from the tailings slurry.

NERCO and DuPont will conduct laboratory tests this month and will build a test facility at DeLamar this spring. If the tests are successful, NERCO will have a full-scale slurry processing facility working by Nov. 1. Estimated cost of the facility is about $2 million.

''The proposed technology has the potential to eliminate cyanide from the tailings pond, which would prevent injuries and mortalities to wildlife,'' BLM Idaho Director Delmar Vail said Friday. ''We are also hopeful that the technology, if successful, could be applied industry-wide and provide long-term national environmental benefits.''

But Vail said NERCO understands that if the technology does not work, some other remedy must be found to eliminate any threat from the pond. In addition, he said NERCO has agreed to take immediate measures to avoid wildlife deaths while the cyanide recovery technology is being developed.