USGS Water-Year Summary for Site 09379500

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	Available Parameters
	00010 Temperature, water(Max.,Min.,Mean)
	00045 Precipitation(Sum)
	00060 Discharge(Mean)
	00095 Specific cond at 25C(Max.,Min.,Mean)
	00400 pH(Max.,Min.,Med.)
	63680 Turbidity, Form Neph(Mean,Min.,Max.)

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Water year 2025: 2025-10-01 to 2026-09-30

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USGS Water-Year Summary 2025

09379500 SAN JUAN RIVER NEAR BLUFF, UT

LOCATION - Lat 37°09'02.44", long 109°52'00.08" referenced to North American Datum of 1983, in SE 1/4 NE 1/4 SW 1/4 sec.07, T.42 S., R.19 E., San Juan County, UT, Hydrologic Unit 14080205, on right bank 2200 ft downstream from Gypsum Creek, 300 ft upstream from highway bridge, 20 mi southwest of Bluff, at mile 113.5.

DRAINAGE AREA - 23,000 mi².

REVISIONS HISTORY -

WSP 1213: 1940. WSP 1313: 1917, 1929. WSP 1343: 1945.

Prior to Aug 31, 2016 the datum of the gage was 4,048 ft above NGVD of 1929 from levels run by the Topographic Division.

SURFACE-WATER RECORDS

PERIOD OF RECORD - October 1914 to current year. Monthly discharge only for some periods, published in WSP 1313.

GAGE - Water-stage recorder. Datum of gage is 4,046.22 ft above NAVD of 1988 from a Level 2 GNSS survey conducted Sep 25, 2019. Prior to Aug 31, 2016, 0.5 mi upstream on left bank. Gage datum was maintained using a Total Station however a +5.00 adjustment was made to the local gage datum required to maintain positive gage heights. Prior to March 16, 1927, chain gages at sites about 1,700 ft downstream at different datums. October 1917 to February 1927, no gage, but estimates of discharge.

REMARKS - Records generally good except for estimates which are fair to poor. Diversions for irrigation of approximately 200,000 acres above station. No diversion between station and mouth of river. Flow regulated by Navajo Reservoir since June 28, 1962.

EXTREMES OUTSIDE PERIOD OF RECORD - Flood of Oct 6, 1911, which is greatest known at Shiprock, NM, probably exceeded that of Sep 10, 1927 at this station but stage was not accurately determined. A step-backwater analysis by Orchard (2001) calculated a flow of 148,000 cfs for the 1911 flood using driftwood in a reach above 8 Foot Rapid as an historic high-water mark. The same study also used the slope-area method to calculate a flow of 154,000 cfs for that event (see USGS OFR 01-314).

EXTREMES FOR PERIOD OF RECORD - (water years 1914-17, 1927-2005) maximum discharge, 70,000 ft³/s, Sep 10, 1927, gage height, 32.0 ft, from rating curve extended above 31,000 ft³/s, and slope-area measurement at gage height, 26.62 ft; no flow Jul 3-13, 1934, Aug 24-27, 29, 1939.

CLIMATOLOGICAL RECORDS

PERIOD OF RECORD -

Precipitation: Oct 18, 2021, to present.

Air Temperature: Oct 18, 2021, to present.

Air Pressure: Oct 18, 2021, to present.

Wind Speed: Oct 18, 2021, to present.

Wind Direction: Oct 18, 2021, to present.

Relative Humidity Percent: Oct 18, 2021, to present.

INSTRUMENTATION -

Precipitation: WaterLog H-340SDI "Smart" SDI-12 tipping bucket rain gage, Oct 18, 2021, to present.

Air Temperature: Vaisala WXT536 multi-parameter weather transmitter, Oct 18, 2021, to Oct 27, 2022. Lambrecht THP(pro) Oct 27, 2022, to present.

Air Pressure: Vaisala WXT536 multi-parameter weather transmitter, Oct 18, 2021, to Oct 27, 2022. Lambrecht THP(pro) Oct 27, 2022, to present.

Relative Humidity Percent: Vaisala WXT536 multi-parameter weather transmitter, Oct 18, 2021, to Oct 27, 2022. Lambrecht THP(pro) Oct 27, 2022, to present.

Wind Speed: Vaisala WXT536 multi-parameter weather transmitter, Oct 18, 2021, to Oct 27, 2022. FTS RM-Young-SDI Oct 27, 2022 to present.

Wind Direction: Vaisala WXT536 multi-parameter weather transmitter, Oct 18, 2021, to Oct 27, 2022. FTS RM-Young-SDI Oct 27, 2022 to present.

EXTREMES FOR PERIOD OF RECORD -

Precipitation: Maximum daily precipitation; 0.84 in, Aug 14, 2022.

Air Temperature: Maximum recorded; 44.3 deg C, Jul 17, 2023. Minimum recorded, -10.1 deg C, Feb 4, 2022.

Air Pressure: Maximum recorded, 896 mbar, Jan 10, 2022. Minimum recorded, 848 mbar, Feb 22, 2022.

Relative Humidity Percent: Maximum recorded, 98.4 percent, Dec 28, 2022. Minimum recorded, 2.6 percent, Jun 13, 2022.

Wind Speed: Maximum recorded, 26.6 mph, May 29, 2022. Minimum recorded, 0.0 mph of several days.

REMARKS - Maximum recorded daily precipitation during the period of record for the rain gage is 0.85 inches on Aug 14, 2022.

WATER-QUALITY RECORDS

PERIOD OF RECORD - July 1929 to current year.

PERIOD OF DAILY RECORD - SPECIFIC CONDUCTANCE: October 1941 to September 1977, October 1980 to July 1999, July 2000 to current year. WATER TEMPERATURE: May 1944 to September 1961, October 1964 to September 1999, July 2000 to current year. TURBIDITY: April 2016 to current year. PH: April 2016 to current year. DISSOLVED OXYGEN: Oct 2021 to present. SUSPENDED-SEDIMENT DISCHARGE: July 1929 to September 1980.

INSTRUMENTATION - Water-quality monitor October 1980 to September 1999, July 2000 to current year. Turbidity and pH sensors added April 2016. Dissolved oxygen sensor added Oct 2021.

REMARKS - Unpublished daily records of specific conductance obtained before water year 1965 were included in the determination of extremes for period of daily record and are available at the USGS Utah Water Science Center, Salt Lake City, UT. Quality of data for specific periods can be obtained by contacting the Utah Water Science Center.

EXTREMES FOR PERIOD OF RECORD -

WATER TEMPERATURE: Maximum, 33.4 °C, Aug 14, 1998; minimum, -0.2 °C, on many days.

SPECIFIC CONDUCTANCE: Maximum recorded, 5,060 microsiemens/cm, Jul 20, 2017; minimum daily, 208 microsiemens/cm, Jun 17, 1952.

TURBIDITY: Maximum, >4,000 FNU, on many days; minimum, 0 FNU, on many days.

PH: Maximum, 9.0 std units, Apr 27, 2018 and May 10-11, 2018; minimum, 7.3 std units, Jul 27, 2022.

Dissolved Oxygen: Maximum, 14.0 mg/L, Dec 20, 2022; minimum, 2.7 mg/L, Jul 28, 2022.

SEDIMENT CONCENTRATIONS:Maximum daily mean, 383,000 mg/L, Sep 21, 1929; minimum daily mean, no flow on several days in 1934 and 1939.

SEDIMENT LOADS: Maximum daily, 15,700,000 tons, Oct 20, 1972; minimum daily, no flow on several days in 1934 and 1939.