THIS IS A PRE-REFERRAL ACTION REGARDING THE FRONTERA CREEK SUPERFUND SITE, IN HUMACAO, PR UNDER CERCLA SECTIONS 106A AND 107A. SEVERAL INDUSTRIES, INCLUDING TECHNICON ELECTRONICS CORP (FORMERLY A SUBSIDIARY OF REVLON, INC) WHICH USED MERCURY IN ITS MANUFACTURING PROCESS, AND REEDCO, INC WHICH USED LINDANE, PREVIOUSLY DISCHARGED THEIR WASTE WATER DIRECTLY INTO FRONTERA CREEK. TECHNICON AND REEDCO WERE FINED FOR THIS PRACTICE. AS A RESULT OF THE POTENTIAL THREAT TO PUBLIC HEALTH IN 1983 THE FRONTERA CREEK SITE WAS INCLUDED ON EPA'S NATIONAL PRIORITIES LIST. IN ADDITION TO HUMAN HEALTH, CONTAMINATION AT THE SITE POSES A THREAT TO AN ENDANGERED SPECIES. FROM 1978 TO 1980, A HOUSING DEVELOPMENT, WAS BUILT ALONG FRONTERA CREEK. THE COMMUNITY BEGAN TO COMPLAIN OF HEALTH PROBLEMS WITHIN A YEAR AFTER THEIR ARRIVAL. IN FEBRUARY '85 THE PR DEPT OF HEALTH SAMPLED THE BLOOD AND URINE OF THE RESIDENTS AND FOUND ELEVATED LEVELS OF MERCURY. SOIL SAMPLES COLLECTED ALSO REVEALED THE PRESENCE OF MERCURY. AS A RESULT OF THOSE INVESTIGATIONS, THE GOVERNOR OF PR ORDERED AN IMMEDIATE EVACUATION OF THE COMMUNITY. IN MARCH 1985 THE EPA BEGAN A FOCUSED REMEDIAL INVESTIGA- TION TO ASSESS THE MERCURY CONTAMINATION AND CONCLUDED THAT MERCURY DID NOT PRESENT AN IMMEDIATE NOR A SIGNIFICANT HEALTH THREAT TO THE RESIDENTS.