Assemblyman William Lancaster (R-Covina) has given up his efforts to secure passage of a bill that would have permitted the collection of tolls on San Gabriel Canyon Road at the entrance to San Gabriel Canyon above Azusa. Bill Nunes, an aide to Lancaster, said the proposed toll, requested by county supervisors as a means of raising money to deal with vandalism and other law enforcement problems in the canyon, turned out to be impractical because of federal law. If the state had imposed a toll, the state would have been required to repay millions of dollars the federal government had contributed to build the road. Nunes said county and federal officials are exploring the alternative of levying a fee for recreation use in the canyon. But that proposal, too, faces difficulties, because the federal government allows fees to be charged in national parks and forests only for specialized purposes, such as campgrounds, and not for general recreation. Much of the canyon lies within the Angeles National Forest.