USGS Water-Year Summary for Site 132626144471771

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	72150 Elevation, GW, LMSL(Mean)

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Water year 2023: 2022-10-01 to 2023-09-30

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USGS Water-Year Summary 2023

132626144471771 EX-4 Mangilao, Guam

Other aquifers
Limestone

LOCATION - Lat 13°26'29.7", long -144°72'4.1" referenced to North American Datum of 1983, Guam County, GM, Hydrologic Unit 22010000,

GROUNDWATER RECORDS

WELL CHARACTERISTICS - Depth 390 ft. Upper casing diameter 6 in; top of first opening undefined, bottom of last opening undefined. Drilled basal groundwater monitoring well. Well diameter 8 inches. Casing material PVC. Casing diameter 6 inches. Sounded depth of well 390 feet (2006). Drilled depth of well 400 feet.

DATUM - Land-surface datum is 153.22 ft above undefined vertical datum. Measuring point: top of pvc casing, marked, 153.61 ft above , May 29, 2008, to Sep. 16, 2015; top of pvc casing, 153.64 ft above , Sep. 17, 2015, to present.

PERIOD OF RECORD - Water-level - Occasional measurements, March 1981 to June 1991, January 1993 to May 1993, March 1995, January 1996, April 2000 to current year. Water-Level Continuous Record--June 2010 to January 2011 as part of the Guam Groundwater Availability Study.

EXTREMES FOR PERIOD OF RECORD -
Highest discrete water level: 8.39 feet above mean sea level, December 13, 1990.
Lowest discrete water level: 4.78 feet above mean sea level, July 17, 1990.

WATER-QUALITY RECORDS

PERIOD OF RECORD - Specific-conductance profiles using a conductivity-temperature-pressure sensor (CTD): 2000 to present. Unpublished records available upon request. Discrete-depth sampling, analysis for specific conductance and chloride concentration: 1981-1989. Unpublished records available upon request. Fluid-resistivity profiles: 1981 to 1984. Unpublished records available upon request.

INSTRUMENTATION - Water-quality monitor with recorder set to approximately 1-second recording interval. Monitor is trolled over the total depth of the well.

REMARKS - Two specific-conductance and temperature profiles are measured during each water year; one at the end of the wet season (January) and one at the end of the dry season (June or July). The CTD is checked against specific-conductance standards. The specific-conductance measurements in the profiles have not been adjusted based on the check measurements, however, the data are available to make adjustments. Depth is measured using a combination of a marked and calibrated cable and pressure readings from the CTD.