MOUNTAIN MOBILE MIX, INC ( M.M. OR THE COMPANY OR THE CO. ) CONDUCTS, AS ONE FACET OF ITS OPERATION, A GRAVEL WASHING SITE NEAR RIFLE, COLORADO. THE SITE IS LOCATED AD- JACENT TO THE COLORADO RIVER AND UPSTREAM FROM THE GRAHAM MESA (RIFLE AND VICINITY) WATER TREATMENT PLANT (MWTP). ON MARCH 26, 1980, WE RECEIVED A TELEPHONE COMPLAINT FROM JIM SHROYER, THEN A MWTP EMPLOYEE. MR. SHROYER COMPLAINED THAT M.M. HAD BEEN DISCHARGING MUDDY WASH WATER INTO THE COLORADO RIVER FOR SEVERAL WEEKS. THE COMPANY DOES NOT HAVE A NPDES PERMIT, WITHOUT WHICH THEY CANNOT LAWFULLY CAUSE ANY DISCHARGE. THE WASH WATER WAS REACHING THE COLORADO RIVER THROUGH A DRAINAGE DITCH AD- JACENT TO THE GRAVEL WASHING OPERATION. ON MARCH 3, 1980, USING A HACH 2100 TURBIDITY METER, MR. SHROYER HAD GOTTEN A READING IN EXCESS OF 1,000 TURBIDITY UNITS FROM M.M.'S DIS- CHARGE. (THE SECONDARY DRINKING WATER STANDARDS, THOUGH NOT SPECIFICALLY APPLICABLE HERE, IS ONE (1) TURBIDITY UNIT. TURBIDITY BECOMES VISIBLE TO THE HUMAN EYE AT ABOUT 10 UNITS AND 1,000 UNITS IS THE MAXIMUM READING ON THE METER.) ON APRIL 4TH, 1980, JERRY BIBERSTINE, A WATER QUALITY SAMPLER FOR THE COLORADO DEPT OF HEALTH, VISITED THE SITE & CONFIRMED THAT THE COMPANY WAS DISCHARGING WASTEWATER INTO THE COLORADO RIVER. HE WITNESSED AND PHOTOGRAPHED THE DIS- CHARGE AND RSULTING PLUME IN THE RIVER. AT THAT TIME MR. BIBERSTINE INFORMED THE PLANT MANAGER