The EPA's ''good Samaritan'' initiative is aimed at encouraging more groups to pitch in to protect drinking water and watersheds threatened by the nation's 500,000 abandoned mines, EPA Administrator Stephen Johnson told a White House conference on the environment.

Some groups have worried about future responsibility if sites they help reclaim become Superfund sites - the nation's worst toxic messes. Trout Unlimited, for example, wants to help the Forest Service clean up acidic mine runoff in Utah's American Fork Canyon. The Superfund law makes those who have worked at toxic waste sites potentially liable for future cleanups.

Trout Unlimited said it will hire experts to do engineering work to clean up the North Fork of the American Fork River with $300,000 raised from private and public sources. The river runs through the Uinta National Forest and private land south of Salt Lake City owned by the Snowbird ski resort.

''Many of these problematic abandoned mines are on private land and those responsible for the pollution are long since gone,'' Johnson said. ''While there have been groups and local communities willing to take on the restoration of these watersheds, the potential liability of touching the sites has long discouraged voluntary cleanup efforts.''

Johnson said that in the case of Trout Unlimited, EPA believes it can interpret the Superfund law ''to remove the fear of liability and costly litigation to allow them to clean up waste from old mines.''

Chris Wood, Trout Unlimited's vice president for conservation, said, ''We want to hold this up as a model to replicate.''