Water-Resources Investigations Report 01-4239

Ground-Water Discharge Determined from Measurements of Evapotranspiration, Other Available Hydrologic Components, and Shallow Water-Level Changes, Oasis Valley, Nye County, Nevada

Table 11. Characteristics of wells used to measure water levels, Oasis Valley, Nevada, 1996-2000

[Shallow wells were installed by USGS to assess the effect of evapotranspiration on the water table. Deep wells existed prior to the study or were installed during the study by non-USGS personnel. The deep wells are located where the water table is relatively shallow (less than 25 ft) and have depths less than or equal to 120 ft below land surface. The source of construction and location information is the Nevada Division of Water Resources drilling logs. ER-OV wells were installed by USGS personnel to observe water levels in the deeper zones (more than 50 ft below land surface) of the ground-water flow system.]

Well name: Names listed in alphabetical order by well category.

USGS site identification (ID): The standard site identification is based on the grid system of latitude and longitude. The number consists of 15 digits. The first six denote the degrees, minutes, and seconds of latitude; the next seven denote the degrees, minutes, and seconds of longitude; and the last two digits (assigned sequentially) identify the sites within a 1-second grid. For example, site 365934116431601 is at 36° 59' 34" N latitude and 116° 43' 16" W longitude, and is the first site recorded in that 1-second grid. The assigned number is retained as a permanent identifier even if a more precise latitude and longitude are determined.

Local site number: A local site identification is used in Nevada to identify a site by hydrographic area (Rush, 1968) and by the official rectangular subdivision of the public lands referenced to the Mount Diablo base line and meridian. Each site designation consists of four units: The first unit is the hydrographic area number. The second unit is the township, preceded by an N or S to indicate location north or south of the base line. The third unit is the range, preceded by an E to indicate location east of the meridian. The fourth unit consists of the section number and letters designating the quarter section, quarter-quarter section, and so on (A, B, C, and D indicate the northeast, northwest, southwest, and southeast quarters, respectively), followed by a number indicating the sequence in which the site was recorded. For example, site 228 S11 E47 09DBD 1 is in the Oasis Valley (Hydrographic Area 228). It is the first site recorded in the southeast quarter of the northwest quarter of the southeast quarter of section 9, township 11 south, range 47 east, Mount Diablo base line and meridian.

Land-surface altitude: Datum is sea level. Altitudes reported to nearest foot were estimated from USGS 1:24,000-scale topographic maps and field observations. Altitudes reported to nearest tenth of a foot obtained from leveling surveys.

Well depth: Datum is land surface. Well depths sounded by USGS or as reported in drilling logs provided by Nevada Division of Water Resources.

Top of open interval: Depth below land surface of top of uppermost well opening.

Bottom of open interval: Depth below land surface of bottom of lowermost well opening.

Type of open interval: P, perforated or slotted casing; S, screen; X, open hole.

ET (evapotranspiration) unit: DGV, dense grassland vegetation; DMV, dense meadow and woodland vegetation; SGV, sparse to moderately dense grassland vegetation; SSV, sparse to moderately dense shrubland vegetation; and UCL, unclassified. See table 1 for more detailed description of ET units.

Contributing lithologic unit: Lithologic unit present at interval yielding water to the well.

¹ Well instrumented for continual data collection.