-STAUFFER CHEMICAL COMPANY'S FACILITY IN SILVER BOW COUNTY, MT (NEAR BUTTE) IS AN ELEMENTAL PHOSPHORUS PRO- DUCTION PLANT. PLANT IS SUBJECT TO 40 PERCENT OPACITY LIMITATION, PER MONTANA ADMINISTRATIVE RULES, 16.8.1405(1). THIS OPACITY LIMIT HAS BEEN APPROVED AS PART OF THE MONTANA STATE IMPLEMENTATION PLAN (SIP) BY EPA, 40 CFR 52.1372. -THE STAUFFER FACILITY HAS EXCEEDED THE 40 PERCENT LIMIT AT ITS FURNACE TAPHOLE SCRUBBER STACK ON A CONTINUED BASIS SINCE AT LEAST JUNE, 1984; STATE AND EPA VISIBLE EMISSIONS OBSERVATIONS OVER THIS TIME REPORT OPACITY LEVELS OF 80, 90 AND 100 PERCENT. -STAUFFER ENTERED INTO A CONSENT DECREE WITH THE STATE OF MONTANA IN A STATE ENFORCEMENT ACTION IN SEPTEMBER 1988; THE DECREE ALLOWS STAUFFER UP TO SIXTEEN MONTHS TO TEST AND INSTALL A NEW CONTROL SYSTEM. DURING THIS TIME, THE STATE AGREED TO TAKE NO ENFORCEMENT ACTION FOR ANY OPACITY EXCEEDANCES. -EPA CONSIDERS THE STATES AGREEMENT AS CREATING AN ILLEGAL VARIANCE AND HAS REFERRED THE CASE TO DOJ TO ENFORCE THE SIP, PER SECTIONS 110(A) AND 113(B) OF THE CLEAN AIR ACT 42 USC 7410(A) AND 7413(B). -ADDITIONALLY, EPA REGION VIII IS CONCERNED THAT ANY RELAXATION OF THE OPACITY STANDARD WOULD CREATE AN UN- DESIRABLE PRECEDENT AND POSSIBLY OFFECT THE BUTTE PM-10 NON ATTAINMENT AREA, SICE THE PARTICULATE MAT