USGS Water-Year Summary 2021
12323700 MILL CREEK AT OPPORTUNITY, MT
LOCATION - Lat 46°06'51.76", long 112°49'11.19" referenced to North American Datum of 1983, in SE 1/4 SE 1/4 NE 1/4 sec.10, T.4 N., R.10 W., Deer Lodge County, MT, Hydrologic Unit 17010201, on right bank at Opportunity, 1.0 mi upstream from Mill-Willow Bypass, and at river mile 1.0.
DRAINAGE AREA - 42.5 mi².
PERIOD OF RECORD - April 2003 to current year.
GAGE - Water-stage recorder. Elevation of gage is 4,940 ft, referenced to the North American Vertical Datum of 1988. April 1, 2003 to July 18, 2006, water-stage recorder at site 400 ft downstream at different datum.
PERIOD OF RECORD - March 2003 to current year.
PERIOD OF DAILY RECORD - TURBIDITY: April 2013 through current year (seasonal record).
INSTRUMENTATION - Turbidity monitor was installed in April 2013.
EXTREMES FOR PERIOD OF DAILY RECORD - TURBIDITY (seasonal records): Maximum, 616 formazin nephelometric units (FNU), June 5, 2017;
minimum, <0.5 FNU, many days July through Sept. during multiple years.
EXTREMES FOR CURRENT YEAR - Turbidity: During period of seasonal operation, maximum, 66 formazin nephelometric units (FNU) May 20, 2020; minimum, < 0.5 FNU many days in August and September, 2020.